These are stories from the
last few weeks...
September 2, 2008: Our Magnificent
Moths
My captive caterpillar herd has
diminished considerably as the summer
has progressed, but a few keep eating away, in no hurry to enter the
pupal stage in which they will spend the winter. Readers will perhaps
remember my telling about their hatching and early care. This was
fairly time-consuming as fresh leaves had to be gathered daily and the
minute caterpillars transferred to them in their closed containers.
Once they were placed in the mesh sacks that enclosed tree limbs,
however – the cecropia on apple and the luna on birch – the chores
became only a matter of empting the droppings (much more pleasantly
called “frass”) every few days and watching them grow.
Even the frass has provided fodder for
study with entomologists, as
some species eject these small pellets with some force, sending them
off the leaves on which the insects are feeding. This seems to be
important, as the frass has been found to give off odors that attract
predatory wasps, major enemies of the young caterpillars. Experiments
have shown that up to 30 percent of caterpillars in some wild
populations can be killed by these predators over just a few days.
The caterpillar is the second stage in
the complicated process of the
creation of a butterfly or moth. Although these beautiful insects in
their adult lives drink mostly nectar, or in some cases, eat nothing at
all, their larvae chew up and eat leaves in prodigious amounts. They
are voracious feeders and many of them do considerable agricultural and
garden damage, and are far better known in their caterpillar stages
than as adults.
A caterpillar has a soft body that can
grow rapidly until its skin is
stretched to its limit. At that point, it forms a new skin under the
old, which then splits and is cast off. Only the head capsule is
hardened and it is equipped with tough sharp jaws for chewing leaves.
Behind the mouthparts are the spinnerets, from which silk is emitted
for various uses such as spinning cocoons, or threads for attachments
or locomotion.
Most caterpillar bodies are made up of
thirteen round segments. Behind
the head are three sections of the thorax, each supporting a pair of
small true legs, recognized as such because they are jointed and often
have a claw at the end. These are retained when the caterpillar
transforms into a pupa and eventually become the legs of the adult.
Abdominal segments 3 through 6 and segment 10 usually bear a pair of
fleshy, stubby little appendages called prolegs that are used for
walking and clasping. Each proleg has a set of tiny hooks arranged in
rings around the tip that allow it to hold on to almost any surface.
People raising caterpillars are warned not to try to remove a tenacious
caterpillar from a support, as its prolegs will sometimes actually tear
off rather than release their grip. During metamorphosis the
prolegs disappear and the butterfly or moth emerges with only the six
true legs.
The caterpillar has 4,000 muscles
(humans have only 629) and move by
contracting the muscles in its rear segments. This pushes fluid forward
into the front segments and stretches them out. It then releases the
hold of its rear prolegs and allows the back segments to catch up. Like
all insects, caterpillars breathe through a series of small openings
along the sides of their thorax and abdomen that branch into the body
cavity through a network of tiny tubes.
A caterpillar has six tiny eyelets on
each side of the lower portion of
its head that are only capable of detecting light. As the larva
develops and matures into an adult insect, these are replaced by more
complex compound eyes that may consist of thousands of tiny independent
photoreception units, each of which is made up of cornea, lens, and
photoreceptor cells. Compared with mammal eyes, compound eyes have poor
image resolution but they have a very large field of view and a good
ability to detect any movement.
Probably the most famous and
well-known caterpillar is the inchworm.
Its body is slender and hairless, and many species have projections
that help them mimic flowers, twigs or foliage. When in danger, some
inchworms stand upright on their prolegs, making them resemble a twig.
Inchworms have the three pairs of true legs at the front and only two
pairs of prolegs on the rear segment, accounting for their strange gait
of humping up their middle segments during locomotion. The adult moths
of inchworms lay their eggs in the late fall, and after the eggs hatch
the next spring, the caterpillars feed for four or five weeks and then
burrow into the soil to make their cocoons. The adults emerge in
November – the female moth is wingless and the inconspicuous male has a
wingspan of about 1 inch — and the cycle begins again.
My caterpillars and the adult moths
they will become are much more
spectacular than the inchworms. The cecropia moths are beautiful
creatures that often have wingspans up to 6 inches and their larvae
measure at least 4 inches before they spin their cocoons. The lunas
have pale green wings that end in long delicate tails, and their
caterpillars are somewhat smaller, but still formidable. I also had a
brief experience with a tomato hornworm – an even bigger caterpillar.
Neighbors found their tomato patch pretty well stripped of leaves when
they returned from vacation and were happy to share the only culprit we
could find. I placed it on one of my plants and covered it loosely with
netting for protection from birds, only to have it immediately
disappear. These caterpillars bury under the dirt to pupate and
transform into large hawk moths that are often mistaken for
hummingbirds. I was sorry to lose it but perhaps the moths will visit
my garden next year and I can be more careful.
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August 26, 2008: The Other Songsters
Perhaps you have noticed in recent
years that the sounds of the insects
that sing in the late afternoon and evening these late summer days have
diminished considerably as you walk around your yard or along a path in
the out-of-doors. The cause in this case is not a noticeable decrease
in the number of the insect singers, new invasive species that have
displaced them, or even global warming. It is our own ears.
The fact is that insect listening is
best done as a child. When we are
young our hearing usually extends from around 30 Hz – a hertz is a unit
of measurement based on one sound wave per second -- to as high as
20,000 Hz. As we grow older, our ears lose their sensitivity to high
frequency sounds and by fifty years of age, the average person has
completely lost the very highest frequencies. When we reach sixty
years, most of us experience considerable hearing loss above
4,000-5,000 Hz and since most insect songs are at frequencies above
4,000 Hz we hear only those few singing in our range. It is no wonder
that those of us pushing eighty years are at a definite disadvantage.
There are about 23,000 grasshopper and
cricket species worldwide, and
each species is said to have its own "song." Most are members of the
order Orthoptera that is generally divided into two groups:
grasshoppers and relatives that have antennae that are shorter than the
body, and crickets and katydids that have antennae as long or longer
than their bodies. Cicadas are also common singers, but they are
considerably bigger and belong to another order that have piercing
sucking mouthparts and wings held roof-like over the body.
The annual cicada sings only during
daylight hours and starts the
insect chorus from the trees in late afternoon with a rising
zing-zing-zing sound that some listeners think sounds like someone
sharpening scissors against a grinding stone. The cicada has a pair of
special sound producing organs, each of which has a stretched membrane
that is controlled by strong muscles. When these contract and then
release they cause the membrane to pop, and when done rapidly, create a
loud buzzing song that is amplified by a hollow area in the abdomen.
At dusk the male crickets begin
rubbing their wings together, dragging
a small peg on one wing across a row of ridges on the other. The result
is a series of clicks similar to what happens when you rub your
thumbnail down the teeth of a comb only so fast that you don't hear the
individual clicks but a trill. Black field crickets used to come into
the basement in our older house and no one minded their cheerful
chirping from the woodpile. The tree crickets produce short, evenly
spaced trills and we hear them constantly from any wooded areas.
Later, the last singers of the day
take over and sing almost until dawn
on warm nights. The katydid is a large green insect that resembles a
leaf and can reach 2 1/2 inches in length. It is named for the rhythmic
song it produces, to which some hearers have given the words
“kay-tee-did” or “kay-tee-did-did”. Katydids produce their songs by
rubbing a file-like structure on the bottom of one wing against a sharp
edge or scraper on top of the other wing. As the file is drawn across
the scraper, thin membranes on the wings vibrate rapidly to create the
sounds.
Rather than rubbing their wings
together, short-horned grasshoppers
(that are sometimes incorrectly called locusts) rub their legs against
their wings. Short pegs on the inner surface of the hind-legs are drawn
against the stiff outer edges of the hind-wings, and the sounds made in
this way are typically very soft and may be difficult to hear. In
contrast, one group, the band-winged locusts, make clicking or rattling
sounds as they fly, often accompanied by flashing of the wings. These
sounds are generated when wing membranes are suddenly popped taut and
often occur during courtship flights, although they may also be used
when the insect is startled into flight.
Some insect enthusiasts have now
adopted an advanced digital device
called “The SongFinder” which was developed for bird watchers who
suffer from high frequency hearing loss and are unable to hear
high-pitched bird songs. Unlike conventional amplifying-type hearing
aids, The Songfinder works by lowering the frequency of high-pitched
songs into a range where the listener can hear. Furthermore, it is a
two-channel "binaural" device that allows the user to determine the
direction and distance of the sound source.
This cacophonous mixture of chirps,
trills, ticks, scrapes, shuffles,
and buzzes -- the songs of grasshoppers, crickets, katydids, and
cicadas serenading their females -- will continue for the next month or
so until cold weather dampens their enthusiasm and finally a heavy
frost will bring the chorus to a close. Winter months are silent and
long... and coming.
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August 19, 2008: Bird Watching is Like
Fishing?
Did you happen to see the
black-bellied whistling duck that reportedly
visited an area farm near some of the floodwaters two weeks ago?
Perhaps other more pressing business held your attention, but its
sighting was a major event for some people. Its presence was announced
on a birders’ hotline on the Internet and soon they arrived from far
and wide to catch a glimpse of this Mexican duck that seldom ventures
so far north. It is a distinctive looking bird with a long neck, long
legs, black belly, and white wing patch, and is notable as it perches
and even nests in trees.
Birdwatchers are a growing and
enthusiastic community. Husband Bill and
I attended an Elderhostel program in Minnesota last fall that was
centered around this topic and led by three avid birders. Local
residents must have rolled their eyes as they rounded a corner on one
of the back roads nearby to find three vans stopped almost in the
traffic lane with their passengers piling out to view some unidentified
bird up in a tree. We calculated that we drove some 600 miles in four
days looking for new species.
Although the practice was frowned upon
by two of our leaders, the third
often produced his iPod that was programmed with birdcalls that played
through a small remote speaker. He would use it in two ways --
broadcast the call of a particular bird in the hopes that it would draw
one of that species to show itself, or play the call of a screech owl.
Any number of small songbirds will not tolerate this little predator in
their territories and will gather to attack and drive it away. When the
recorder was played, the first to arrive was usually a chickadee, and
the bird would search around the speaker for the intruder. It would
soon be joined by others until nearby branches and shrubbery were alive
with angry birds.
The observation of live birds in their
natural habitat has only become
a popular pastime in the last hundred years. In the 19th century almost
all students of birdlife had to shoot their subjects to get a close
look at them – a process that did nothing for the population of the
more rare species. Modern bird-watching has been made possible largely
by the development of affordable binoculars, as even the least
expensive pair can make a big difference in appreciating and
identifying one of the tiny creatures.
A case in point was a sighting we made
a few years ago in Belize. We
were in that country for another Elderhostel and were spending a few
days beforehand up in the highlands south of our destination at some
Mayan sites. Staying at the same resort was a traveling birding group
and they were quite noticeable with their ever-present binoculars and
cameras with impressive lens systems attached. Husband Bill and I saw
movement in a tree along the main path, and using the tiny inexpensive
binoculars we carry on trips for just such occasions, saw that it was a
pigmy owl – one of the species the birders were seeking. Within seconds
of the discovery, we were surrounded by many thousands of dollars worth
of high-tech equipment, and found ourselves to be mini-celebrities that
night for having found the elusive bird.
Bird watching is something like
fishing when you throw the catch back
into the water, or perhaps more like collecting stamps or figurines.
The object for many is to find and identify as many species as
possible, a process that requires travel to likely habitats, patience
in searching once in the area, and either a knowledgeable companion or
good identification books to put names to what is found. The rewards
are many: hobnobbing with a variety of fascinating people with a common
interest, an excuse to visit new and sometimes remote areas, and an
incentive to spend lots of time in the outdoors. Most birders
have life lists that they have kept for years, and most also have other
specialized lists as well, such as backyard lists or state lists,
generally containing date, time and location of the sighting, and even
habitat details and weather. Casual enthusiasts such as Bill and I
don’t bother with the bookkeeping, but are always on the lookout for a
new species and carry binoculars whenever and wherever we hike.
In 2001, the National Survey of
Fishing, Hunting and
Wildlife-Associated Recreation reported that the state of Wisconsin had
3.1 million people observing wildlife, and that they spent $1.3 billion
on equipment and other trip-related costs each year. Of that amount,
visitors spent $152 million on food and lodging and $78 million on
transportation. Birding was reportedly the most popular wildlife
watching activity, and over the past 10 years, the Wisconsin Department
of Natural Resources has put together several different nature trails,
collectively called the “Great Wisconsin Birding and Nature Trail”.
Also each spring, birders celebrate International Migratory Bird Day on
May 13 by hosting 19 events for visitors around the state. Even more
impressive was the national report last year on outdoor recreation
activity that reported that wildlife watchers spent $45 billion of a
total of $120 billion spent on all wildlife-related recreation
nationwide. Birdwatching is certainly big business but most of us are
content to keep our eyes open and ears tuned to the sights and sounds
of these feathered creatures and enjoy their presence in our yards and
neighborhoods.
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August 12, 2008: Spiders: Oh, My!
Take a walk shortly after dawn one of
these foggy mornings and you will
probably be amazed at the numbers of flat webs spread across your lawn
made visible by the dew. These are the work of one of our very common
spiders called the sheet weaver (obviously from the shape of its
web). You might even want one of the tiny spiders to climb onto
your clothes, for if you give credence to the old British superstition
you will believe that it has come to spin you new garments, meaning
financial good fortune. You also may be interested to learn that the
world record for the largest outdoor web was created by many thousands
of these spiders at Kineton High School, Warwick, UK, that covered its
entire 11-acre athletic field.
Sheet web spiders come in hundreds of
species, many of which are so
small that they must be examined with a powerful hand lens. My favorite
is somewhat larger and grows to about 0.2 inch long – the bowl and
doily spider. It weaves a fairly complex structure consisting of an
inverted dome-shaped web suspended above a horizontal sheet web (the
doily). The spider hangs from the underside of the "bowl", and when
small flies, gnats and other small insects land on the webbing, it
grabs them.
Spiders belong to a large group of
related creatures called arthropods,
a term meaning "joint-legged", as all have hard outer-body coverings
with bendable leg joints. The tough covering is similar to a skeleton,
only it is worn on the outside of the body and acts both to support and
protect. As the creature grows, this "exoskeleton" must be shed, making
way for the larger version.
Mites, ticks, daddy longlegs, and
scorpions are close relatives of
spiders and all have 4 pairs of walking legs and hollow fangs adapted
for liquid feeding instead of jaws with teeth. Spiders have two unique
features, however -- they have spinnerets, which secrete silk during
all stages of life, and they use a unique form of mating, in which the
male transfers sperm to the female using special appendages near the
mouth. In addition, most spiders have eight eyes, although many do not
see very well and rely on sensing vibrations with the hairs on their
legs. Almost all of the 105 spider families have venom glands, and once
prey is caught, the spider injects poison and digestive juices that
turn its victim’s insides into a "soup" which is then sucked up.
There are generally two types of
spiders, depending on how they capture
their prey—hunting spiders and web-builders. All produce silk but only
about half the species construct webs to capture food. Spider silk is a
remarkably strong material and is able to stretch up to 40% of its
length without breaking. It is composed of complex protein molecules
that are pulled through silk glands called spinnerets that somehow
change it from a stored gel into solid fiber. Depending on the species,
spiders will have from two to eight spinnerets, usually in pairs, and
each produces a type of thread for a specific purpose such as web
construction, defense, capturing prey, or moving about.
Our most visible and beautiful web is
probably that of the golden
garden spider, an orb weaver that produces a large flat, wheel-like
structure. This may reach two feet across and always has a zigzag
pattern of silk down the middle. It will contain some 33 yards of silk
thread with an average diameter of 0.15 mm, so small that we are able
to see the web only because of the reflection of sunlight on the
threads.
The orb spider rests on a prominent
weed stalk and releases a thread
that the wind carries to another nearby stem. It then crosses this
“bridge” dragging a loose thread to another anchor to form a “Y”. From
this foundation it attaches other radii until it has a wheel with many
spokes, upon which it lays a spiral of sticky threads and then hangs
head down in the center awaiting prey. If the web is damaged, the
spider removes the silk in the morning by eating it, leaving only the
first bridge line, and constructs a new web in the evening.
Golden garden spiders mature and mate
in the early fall. The female
lays several hundred eggs and the hatchlings over-winter in a silk egg
sac that she hangs from a plant stem. Other insects also use the sacs
to protect their eggs and in one study, nineteen species of insects and
eleven species of spiders emerged from collected cases. The cases
partially protect the spiderlings but the vast majority are opened and
emptied by birds. In spring, the survivors emerge and disperse.
Not all the spiders in our yard make
webs. The wolf spider either
pounces upon prey, even chasing it over short distances, or lies in
wait for a victim. It carries its eggs in a round egg sac attached to
the end of its abdomen. The jumping spider has an internal hydraulic
system that extends its limbs by increasing the pressure of body fluid
within them. This enables the spider to jump 20 to 60 times the length
of its body. Spiders are the stuff of horror films but they are the
first line of defense against the insect hordes that threaten to engulf
us.
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August 5, 2008: Robins and More
Probably no bird in this country is
more widely known than the robin.
It has adapted itself to living near people -- claiming our lawns as
its hunting ground, building its nest in our trees, and singing its
cheerful song to us at dawn throughout the summer months. Connecticut,
Michigan, and Wisconsin have designated it as their state bird but it
can be found all across and up and down North America.
Each spring the male robin hurries
back from his winter vacation to
stake out his territory. He typically went no further south in the
autumn than was necessary, and a few didn’t bother leave at all, having
chosen to hole up in sheltered spots and survive on dried berries and
whatever they could find. Competition for prime spots is strong as the
female seems to choose her mate by the quality of his territory, and
the sooner he can obtain control over a good nesting spot the more
likely a comely female will appear. When she does, the male will begin
to sing and display, expanding his tail feathers and lifting them until
they fan above his head. If the female seems interested, he will pursue
her with a quiet hissing sound until she accepts or rejects him in
which case he will try again with another female. Once a robin pair
mate, the male will chase off any other intruding males.
A good nesting site is usually about
ten feet above the ground on a
forked tree branch, although we have had birds build on the steps to
the loft in the barn, on rafters in the shed, and all sorts of other
sites. The nest itself is in the shape of an open cup and is
constructed of a foundation of dry coarse materials like grasses,
twigs, and twine with a mud layer compressed against it. The inner
lining is created from soft grasses and strings and she will use her
body to press the materials firmly in place, going round and round
until she is satisfied that all is perfect.
After laying a glossy greenish-blue
egg each day for three or four
days, the female will begin to incubate them, rarely leaving the nest
and relying on her mate to bring her food. When she does take a break,
a cowbird sometimes tries to lay its egg in a her nest, but robins are
unusually adept at detecting any intruding egg and usually either poke
holes in it with their beaks or push it out of the nest. Once the
chicks hatch, they only remain in the nest for about two weeks and are
soon flying about after their parents. The female often re-nests, at
which time the male takes over the responsibility for the care and
training of the older offspring. When a female robin is not busy with
incubating eggs or caring for young, she reportedly builds as many new
nests as she can. Usually, most are never completed, but she seems to
have an overwhelming urge to work at them.
Robins are thrushes, a large family of
birds that are mostly found in
Europe and Asia. Most New World thrushes are brown and have speckled
breasts, and it is interesting that the two species in our country that
don’t – the robin and bluebird – have spotted breasts as juveniles.
Thrushes are well known for their
beautiful songs and my favorite is
the wood thrush, perhaps because it is associated with the deep woods
and has an almost ethereal sound. The first low-pitched notes are
almost inaudible and followed by a louder phrase that is often written
ee-oh-lay. The third part is a trill-like phrase made up of pairs of
notes, as the bird is able to sing two notes at once. Each individual
bird has its own repertoire based on combinations of variations of the
three parts.
The wood thrush has a cinnamon-brown
head and back and a white breast
and belly with large dark brown spots. It, along with many of the other
thrushes, is considered a neotropical songbird – a term that refers to
those species that spend about eight months of the year wintering in
Central and South America and the remaining months on their breeding
grounds in North America. The wood thrush has become a symbol of
the decline of these birds of eastern North America, having dropped 43
percent since 1966. The breaking up of North American forests giving
predators and cowbirds access to wood thrush nests, and the continued
destruction of forest in Central America where they winter, are thought
to be major causes. Despite this drop, the wood thrush has not been
listed as a threatened species – and there are still many to grace our
woodlands.
We have never seen a veery in our
upland woods, but it was very much in
evidence at our cabin in the low wet woods in Columbia County. It is
relatively unmarked among the thrushes, as its speckles are faint, and
it has pale or non-existent eye rings, but its song is distinctive with
several quick phrases that drop in pitch. The Swainson’s, gray-cheeked,
and hermit thrushes pass through our area during migration, but only
the hermit is easily identified as it works noisily through the dry
leaves on the forest floor looking for bugs. Its rufous tail is a
give-away. Of all the thrushes, it and the bluebird are the only ones
whose population seems to be increasing across the continent. Bluebirds
deserve their own story so I will write about them another day, but all
the thrushes are very special and well worth getting to know.
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July 22, 2008: Moles or Corn?
Well, it has finally happened. Against
all odds, I have decided that I
have been disseminating incorrect information – in other more succinct
words – I goofed! Each succeeding gardening season I have been having
fewer corn seeds sprout in my vegetable garden. We even went to the
extreme of planting some seed wrapped in bits of steel wool and copper
scrub pads and slipped between the strands of heavy plastic cord. The
cord was left, as well as strands of copper, but the seeds and even the
steel wool disappeared! It has been very obvious that moles were
involved, as their tunnels appeared within days of planting and ran
right down the rows, but I, having read the statements of many
“experts”, was convinced that mice in the tunnels ate the seeds. Source
after source asserted that moles were carnivorous, dining only on
earthworms, grubs and other ground-dwelling creatures. Read these:
“It has long been known to
scientists, through careful study and
investigation, that the diet of moles consists mainly of the insects,
grubs and worms to be found in the soil… While plant fibers or rootlets
show up… in no case was the amount of identifiable plant tissue more
than might have been taken in incidental to the ingestion of other
food” (i.e. animal tissue). from a farm bulletin from Kansas State
Agricultural College.
“Moles are often accused of
damage to bulbs and garden crops --
damage which is really done by mice that invade their burrows.” Nature
Bulletin No. 514-A Forest Preserve District of Cook County (Illinois)
“Moles are almost entirely
carnivorous; however, it is true that moles
can indirectly kill plants. They do this in two ways: The tunnels
created by moles will often be used by other small animals… The mole
will scrape the dirt away from the roots in search of food.” Mole-Pro,
seller of mole traps.
Since I always believe anything I read
on the Internet, I accepted
these pronouncements as gospel, despite the evidence in my own garden.
Now, with more diligent research, I find there are others who know
better. In Habits of the Common Mole, F. A. Hanawalt of the
Department of Biology, Otterbein University reported that “Moles are
often said to be entirely insectivorous. It was shown, to the author's
satisfaction at least, that moles are guilty in some cases of eating
sprouted corn and in rare instances of eating roots and tubers. Moles
in captivity will eat soaked corn readily… “. I have now discovered
other similar sites and I now am faced with the choice between eating
homegrown sweet corn or plotting the extermination of the marauders.
Few people have ever seen a mole. That
is because this strange animal
lives its entire life underground. It has a six-inch, torpedo-shaped
body covered with velvet-like fur that has no nap, so that it can
easily move through its underground tunnels either forward or backward.
It has a cone-shaped head with a long sensitive snout used for feeling
out earthworms, grubs and other food (like corn seeds!), and a short
naked tail that guides it when moving backwards along the runways.
One of our species, the star-nosed
mole, gets its name from an
odd-looking ring of fleshy appendages that fan out around its nose.
These are covered with thousands of unique sensory receptors called
Elmer's organs that presumably assist the animal in finding food. By
contrast, the Elmer’s organs of the common mole lie below a thick layer
of skin and do not seem to be of much use. All moles rely heavily on
their senses of smell and touch, as their extremely tiny eyes are
little more than thin membranes that allow them only to sense light and
little else.
A mole literally "swims" through the
soil in its search for food. Its
shoulders and forelegs are tremendously powerful with broad,
shovel-like paws, each armed with five heavy claws, and these are
brought forward alongside the snout, then thrust outward and backward
in a breast stroke, pushing the soil aside and pulling the animal
forward. The soil above arches and cracks leaving a humped and broken
trail and excess earth is pushed into heaps above the surface.
An adult mole lives a solitary life
and avoids contact with other moles
except during the spring mating season when a male will range some
distance in search of females. The female mole ordinarily has one
litter of four young in a deep nest chamber in April or May. The naked
and helpless young grow quickly and, at the age of three months they
are nearly as large as their parents. In autumn all move into deeper
tunnels below the frost line and remain active all the winter.
A mole has an enormous appetite and
has been reported to eat the
equivalent of its own weight each day. Away from our lawns and gardens
it is considered to be an extremely beneficial animal, but right now it
is definitely on my list as an undesirable. I will probably resort to
coating the seeds with something next year, but as the reports on this
control are not encouraging, I may have to invest in some traps. Oh,
dear…
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July 15, 2008: Which is Which?
All of us can probably remember being
taught in science class that some
insects receive protection because they strongly resemble another
species that stings or is toxic. One example often given was that of
two butterflies – the monarch and the viceroy – both of which have
orange and black wings. The only noticeable difference between the
adult insects is in the pattern of black veins on their lower wings, as
the monarch has a jagged vein across the lower wing while the viceroy
has a continuous line.
The two species are actually very
different. The caterpillar of the
viceroy is greenish brown with a whitish saddle, and has horns with
short thick branches on four of its segments. It feeds on the leaves of
willow, poplar, and cottonwood trees, and over-winters as a chrysalis.
The monarch caterpillar is white with yellow and black stripes around
its body and two black fleshy filaments on each end. It feeds
exclusively on milkweed leaves and transforms into a roundish light
green chrysalis decorated with gold spots. In the fall, these
butterflies migrate to Mexico, traveling several thousand miles.
The theory has always been that since
many predators tend to avoid the
monarch after one taste, because of chemicals it stores in its body
from its milkweed feedings, they also avoid the viceroy because of its
similar looks. Now new research has discovered that the viceroy is
actually more unpalatable than the monarch and that each may receive
protection from the other.
The willow family, upon which the
viceroy caterpillar feeds, produces
salicylic acid in its bark and leaves. Willow bark extract became
recognized for its medicinal effects on fever, pain and inflammation in
the mid-eighteenth century and later became the primary ingredient in
aspirin, but excessive use can cause uncomfortable side effects. The
viceroy caterpillars store up the salicylic acid in their bodies and it
makes them bitter and unpalatable. It also causes digestive irritation,
bleeding, diarrhea, and even death when consumed in high doses.
Most people are familiar with
milkweed. As children we were fascinated
with the white sap in its stems and leaves, as well as the pods full of
seeds that were equipped with parachutes. Milkweed pods were even
gathered during World War II and the floss was extracted and used as
fill for life jackets. The milky juice contains alkaloids and several
other complex compounds, and also a latex that was researched
extensively as a natural source for rubber by both Germany and the
United States during that war. (The major commercial source of natural
rubber latex has always been a tropical tree, largely because it can
produce a continual supply of latex if wounded. Other plants containing
this substance include figs, lettuce, euphorbias, and even the common
dandelion.) This caustic sap presumably protects the plant from being
eaten, although the monarch caterpillar and the larvae of a variety of
other beetles, moths, and true bugs do feed on the plants because they
are not sensitive to its chemicals.
Mimicry has long been a topic of
interest to the scientific community.
Many insects, as well as other organisms, resemble other species for
the obvious reason that they are closely related, but there are
numerous instances where very different species have evolved to look
alike. Sometimes only one of the involved species receives a benefit
from this situation such as the clearwing moths that resemble wasps.
The moths presumably receive protection by looking like dangerous
predators, while the wasps aren’t affected one way or another. Often
the mimicked insect has advertised its danger with bright warning
colors and the similar coloring protects the mimic, despite its
harmless nature.
Fritz Muller was a German zoologist
who described a different type of
mimicry in 1878 when he discovered that in a number of instances
several unpalatable species share a similar warning pattern. He
suggested that a predator who has had a bad experience with any one of
these would avoid all of them, thus benefiting everyone. Such a
situation is now called Müllerian mimicry after him and it
describes the group into which the monarch/viceroy relationship has
been placed. Incidentally, the viceroy exhibits additional mimicry in
both its larval and pupal stages as their form and color strongly
resemble bird droppings, although I’m not sure any bird would be
fooled. This would put it into the former type of mimicry for those
portions of its life.
Monarch butterflies are usually much
more commonly seen than the
viceroy and many people do not even realize that they are two different
species. Still, they can be readily distinguished even at a distance as
the viceroy flits around energetically, while the monarch lazily floats
here and there. This season, at least here at the farm, we have seen
many viceroys and almost no monarchs; last year it was the other way
around, and I hope the monarchs will still make a showing before the
summer is over. We grow milkweed specifically for them in the garden
and enjoy watching the caterpillars grow up, change into their
jewel-like chrysalises, and then emerge as adults before moving on. I
have never found a viceroy caterpillar, but I understand that their
eggs are laid high in the treetops so that the larvae would be far out
of sight if growing in our big willow. If both the caterpillars and
chrysalises look like bird droppings, I’m not sure I would recognize
them if I saw them anyway.
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July 8, 2008: Red Heads and More
Red-headed woodpeckers have been very
much in evidence around the farm
and neighborhood this year, after years with very few sightings. The
Breeding Bird Survey has indicated that the species is declining over
much of its breeding range, and the reason given is usually loss of
suitable habitat and the invasion of European starlings that take over
available nesting holes. Why that should affect the red-headed more
than other woodpecker species that seem to be managing pretty well is
hard to understand, so it may be that other undiscovered factors are in
play. Whatever has been happening, their numbers have rebounded
in our area, as I have seen dozens of these striking birds in past
weeks.
The red-headed is a medium-sized
woodpecker distinguished by its bright
red hood, white chest, and black wings with large white panels that
show up prominently both at rest and in flight. All woodpeckers have
red on their heads, presumably to grab the attention of the opposite
sex when they drum in courtship, but only the red-headed have
completely red heads. I should point out, however, that juvenile heads
are grey and don’t get their color until they are old enough to breed.
This is one of the most aggressive
members of the family and has the
most varied diet. It will eat seeds of beech and oak, nuts, berries,
fruit, insects, bird eggs, nestlings, and even mice (presumably dumb
ones). In addition to attacking other birds to keep them out of its
territory, the red-headed is also known to remove the eggs of other
species from nests and nest boxes, destroy nests, and even to enter
duck-nesting boxes and puncture the duck eggs.
The red-headed is one of only four
woodpeckers known to store food, and
often covers its hoard with wood chips or bark. It hides insects and
seeds in cracks in branches and under loose bark, and has even been
seen to stash prey under roof shingles. Grasshoppers are regularly
stored alive, but wedged into crevices so tightly that they cannot
escape. The red-heads are less likely to drill for food than other
woodpeckers; instead, they fly down to the ground to capture insects or
snatch them from the air.
The male establishes the territory and
defends it by drumming and
calling a loud "tchur-tchur." He chooses a natural cavity nest site if
possible or excavates a new one if necessary, and fends off competitors
with aggressive displays by spreading his wings, fanning his tail while
bowing and bobbing. When a female appears, he will stretch his neck and
hump his shoulders with his feathers sleeked back, and if she is
receptive, she will tap on the outside of the nest while he taps on the
inside. Four or five white eggs are laid in May with incubation and
care provided by both parents. There is usually only one brood a year
in the northern part of their range, although they will often re-nest
if the first brood is not successful.
A woodpecker has several
characteristics that set it apart from other
birds. Its feet are adapted to clinging to a tree trunk with two toes
pointing up and the other two point down, in contrast to those of other
birds that have three toes pointing up and just one back. It has
reinforced tail feathers that allow it to lean back from a vertical
surface and chisel with its beak. Its brain in tightly enclosed in its
skull and padded with cartilage so that repeated pounding on hard wood
does not damage it. Its strong, pointed beak acts as both a chisel and
a crowbar to remove bark and find hiding insects. But perhaps its most
unique feature is its tongue.
In order to reach prey inside wood, a
woodpecker's tongue must be
longer than its bill. In the red-bellied woodpecker the tongue extends
about three times the bill length but in other species the tongue is so
long it forks in the throat, goes below the base of the jaw, and wraps
behind and over the top of the head, where the forks rejoin and insert
in the bird's right nostril or around the eye socket. Within the entire
length of woodpecker's tongue lies a series of tiny bones sheathed in
muscles and soft tissue. These fold up accordion-like along part of
their length and when the woodpecker wants to stick out its tongue, it
contracts muscles near the base, forcing the bones forward and out of
the bill. Relaxing the muscles allows the tongue to shorten and brings
it back inside. The tongue also contains paired lengthwise muscles that
move it side to side.
While feeding, a woodpecker listens
for sounds of grubs chewing inside
a tree and then drills out a hole just wide enough to insert its beak.
Wood-boring beetle larvae often form extensive tunnels and when the
woodpecker's bill breaches one of these tunnels, the bird extends its
tongue and probes around. If it locates a grub, its sharply barbed
tongue skewers the soft body and then withdraws the impaled grub.
Watch for one of these fascinating and
strikingly beautiful birds
perched on a branch or utility pole or darting after a flying insect.
We hope this comeback will prove permanent.
July 1, 2008: About Lightning Bugs
Mother nature has done it again – put
together another seemingly
impossible scenario that our scientists with all their expertise and
ingenious paraphernalia have not been able to duplicate – and it has to
do with a little bug that almost all of us as children collected on a
summer’s evening. A firefly is about ½ inch long, cigar-shaped,
and flies about in our yards, but what makes it exceptional is the
light it gives off, as even its eggs and larvae glow. There are about
136 different species around the world and they are common in the
eastern half of this country as well as in warm, humid areas around the
world.
Usually at dusk, the male firefly
emerges from hiding and flies about,
emitting one or a series of short flashes depending upon his species,
at regular intervals. The female waits on a low perch, and when a male
approaches, will give off an answering flash. Exchanges of signals are
repeated several times until the pair find each other, and then with
luck the male will escape, as given the chance female will devour
him. After mating, the female will deposit her eggs in damp soil,
and in about three weeks young sowbug-like larvae will hatch with tiny
spots on their undersides that glow softly. All firefly larvae produce
light, possibly as a defensive measure, as it has been shown in the
laboratory that predators avoid such glowing objects after experiencing
their taste. The larvae are voracious predators that eat earthworms,
snails, slugs, and mites, injecting strong digestive juices into their
prey before sucking out the insides and leaving an empty skin. Most
firefly larvae live one to two years and are found in rotting wood or
other forest litter. In late spring they change into pupae, and in
about 10 days, emerge as new adult beetles that will live as long as it
takes to mate and produce eggs, often only a few days.
The last few segments of an adult
firefly’s abdomen are made up of
thousands of specialized cells that contain luceriferin and luciferase,
rare chemicals that generate light in the presence of oxygen, as well
as an enzyme that provides energy for the process. The light emitted by
fireflies is unique in that nearly 100 percent of the energy is given
off as light. This is in contrast to tungsten electric lights where
only 10 percent of the energy emitted is light and the other 90 percent
is given off as heat. Although a few other insects can produce light,
fireflies are the only ones that can flash their lights at will and it
has only been very recently that scientists have discovered how it is
accomplished.
Neurobiologists at Tufts University
were puzzled because they could
find no nerve link to the light-producing cells in the firefly’s tail,
although they did find that they could cause the cells to glow if they
exposed them to molecules of nitric oxide gas in the presence of
oxygen. Furthermore, they observed that the cells had a thick outer
layer of mitochondria, a substance that reacts with oxygen to create
energy for the cell and guessed that these mitochondria could block any
light-creating chemical reaction. They also discovered that a signal
from the insect’s nervous system activated an enzyme that produced
nitric acid that deactivated the mitochondria. As the nitric acid
signal decayed, the mitochondria resumed their oxygen consumption that
turned the light off -- all of this occurring in a fraction of a
second. The fact that nitric acid passes through cell membranes,
degrades within seconds and must be made fresh for each use makes it an
important transmitter and signaling molecule.
The really fascinating part of this
story is that scientists have found
that luciferin and luciferase are extremely useful as markers in
research on such problems as cancer, multiple sclerosis, cystic
fibrosis and heart disease. As all living cells already contain the
energy-providing enzyme, injection of the firefly's chemicals cause
flashes of light that can be measured and used to detect energy
problems in human cells. Now, electronic detectors using firefly
chemicals are also used to signal that milk, food or water may be
contaminated with bacteria, and detectors have even been placed in
spacecrafts to look for earth-life forms in outer space. I read that if
as little as one quadrillionth of a gram of the enzyme enters the
rocket's detector, a flash of cold light will be given off and recorded
by earth-bound scientists.
Although most of the luminescent
species are insects, the capability is
also present in some bacteria, fungi, algae, one-celled animals,
segmented worms, arthropods and fishes. Some, like the fireflies, use
their light in courtship, while others use the flashes to frighten off
enemies or attract prey. The colors produced vary, as well, as some are
red, others blue-green or yellow. The problem is that not only are
luciferin and luciferase quite rare but they have so far proved
impossible to synthesize. This has made the propagation of fireflies a
high priority activity in some circles and the Sigma Chemical Co. of
St. Louis, Missouri purchases and provides fireflies throughout the
world for conducting research in a wide variety of scientific areas. I
am told that they will pay a penny for each bug if you will send them
at least 25,000.
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June 24, 2008: Miracle Moth
It seems there is something almost
miraculous about the appearance of
the exquisite silk moths that hatched from my cocoons this past week.
Last year I tended dozens of caterpillars for several months and ended
up with cocoons from four species: the big beautiful cecropia with its
6-inch wingspan, the much smaller promethea, and the less-often-seen
luna and polyphemus. All are present here on the farm naturally, but we
seldom see them because they live only a few days as adults and most
fly only at night.
Even though I lived in an urban area
as a child, there were plenty of
hedges, shrubs and trees in our yard and throughout the town, and we
had a variety of butterflies and moths. Each winter I almost always
found at least one cocoon and often had several that I carried home. I
carefully stored them on our screened back porch, after learning early
that keeping them indoors in the warmth would cause the moths to emerge
far too early for a safe release. I always marveled at the beauty of
the insects that emerged in the spring, but it was not until a few
years ago that I collected eggs from mated females and raised the
caterpillars as well.
Butterflies and moths have four wings,
two forewings and two hind wings
that are powered by strong muscles that move the wings up and down in a
figure-eight pattern. The wings are composed of two layered membranes
that are supported by tubular veins, and when the adult insect emerges
from its pupa, they are crinkled and wet. It then hangs upside-down and
pumps fluid into the veins in the wings to inflate and expand them and
must wait for the wings to dry before it can fly. Covering the wings
are thousands of colorful scales made of tiny overlapping pieces of
chitin, together with many hairs.
Although quite similar, butterflies
and moths have a number of
differences: butterflies fly by day while most moths fly after dusk;
butterflies have slender hairless bodies but most moths have fat furry
bodies; butterflies have hair-like antennae that end in knobs but moth
antennae lack the knobs and often branch like feathers; butterflies
typically hold their wings up vertically when at rest while most moths
hold their wings out flat; the pupae or resting stages of butterflies
(called chrysalises) are naked and exposed while those of moths are
usually formed inside woven cocoons or hidden under the soil. They both
belong to the same insect order, however, that is divided into some
180,000 species.
The giant silk moths are the largest
moths in the United States and
Canada and emerge from their cocoons in June. They live only long
enough to mate and lay eggs and then die, as they have only rudimentary
mouthparts and eat nothing during their short adult lives. In about two
weeks, tiny caterpillars that seem to be mostly mouths eat their way
out of the eggs and then begin to feed on the leaves beneath their
feet. Each species has only a few host plants that they can use and the
mother moth has carefully sought them out using sensors on her antennae
and feet to detect chemicals that are given off by them. My various
caterpillars fed happily on the leaves of birch, wild cherry and apple
trees.
The caterpillars are little more than
eating machines that spend the
next four to six weeks filling their expandable bodies with food,
splitting their skins when these become too tight and then growing some
more. Most become food for birds and other hungry creatures, but those
that survive go through an amazing transformation. First they use a
pair of specially modified salivary glands in their mouths to produce
an endless strand of silk that they weave into a tough shroud. Inside
the completed cocoon, each splits its skin a final time revealing a
legless, wingless object with only the impressions of its future self
embossed onto its skin. Most spend the winter in this form, but inside
the pupa a cluster of dormant cells begins to grow and divide, feeding
upon the old caterpillar cells until the insect takes its new form.
When a female moth emerges from its
cocoon, it hangs quietly in place
until late in the evening. Then it extends a gland from the tip of its
abdomen and emits a chemical pheromone whose molecules float off on the
air currents. Male moths use their feathery antennae to detect the
chemicals and have been known to travel many miles to a female. As soon
as one finds her, he presses his tail to hers, effectively shutting off
the source and the other suitors disappear almost immediately to look
elsewhere.
I was not able to collect eggs from
the luna and polyphemus moths that
hatched from my cocoons, but I do have some extra eggs of the cecropias
and probably will have some of promethea, as well. If any of you are
interested in trying to raise a few, give me a call. You will need a
good supply of leaves (I use apple for the cecropia) as they grow to be
very large caterpillars and are hearty eaters. I fed some in a homemade
cage and put the others in a mesh sleeve that was pulled over an apple
branch – a system that is far less bother and that works very well if
you have a convenient tree. Either way, you will be able to observe
this process from start to finish, and next spring with care and a
little luck you will have your own spectacular show as the moths appear.
_____________________________________________
June 17, 2008: Frogs, Toads, and Salamanders
It sounded as if some disgruntled
musician was twanging on a loose
guitar string, and I knew that the green frogs were adding their voices
to the amphibian chorus at the pond. The rains have been the sole topic
of conversation around the area this past week, with sad tales of
inundated crops, flooded homes, difficulties with travel, wet
basements, and even drowned animals. Still, there are creatures that
have actually enjoyed this awful weather – namely our frogs, toads, and
salamanders.
The term amphibian means "both life
forms" and refers to animals whose
development almost always requires that they live part of their lives
in water and part on land. Wisconsin boasts twenty-one native amphibian
species -- eleven frogs, one toad, and seven salamanders. Some breed in
temporary ponds that are formed by melting snow or rain, some only
inhabit lakes and permanent wetlands, while others use woodland pools.
Amphibian eggs have yolks that are
grayish yellow and are usually
surrounded by a greenish gelatinous material. Some are attached singly
or in masses to aquatic plants, others are in long strings, and still
others float on the surface of the water. Those that are exposed to
direct sunlight often develop dark pigment on the exposed side, a
characteristic that is thought to protect the developing embryo from
ultraviolet radiation and to absorb heat.
Frog and toad tadpoles feed on algae
and other minute plant matter and
as they become mature, they undergo remarkable changes. First, they
grow back legs, then front legs, and then slowly reabsorb their tails.
At this point, the tadpole stops eating and the tail tissue provides
nourishment as its digestive system switches from utilizing plant
material to living prey and its respiratory system changes from
breathing with gills to lungs. Most tadpoles mature and change into
adults within weeks, while others may take several years.
Salamanders are much less likely to be
seen than frogs and toads, but
it is because of their retiring habits rather than their numbers.
Research in New England has shown that the mass of salamanders exceeds
the bird and mammal life in some forests. Salamanders are sometimes
confused with lizards, but reptiles have scales on their bodies and
claws on their toes and salamanders have smooth or warty moist skins
and are clawless. Most cannot travel very far from water where they lay
many jelly-like eggs that hatch into gilled larvae that look similar to
small fish. Juvenile salamanders, unlike tadpoles, have bushy gills and
projections near their necks that help them stay upright in murky
water.
As the salamander larvae mature, they
absorb their gills and develop
lungs and feet. Mudpuppies are an exception and never loose their
larval looks. Another unusual species, the central newt, has a unique
development that depends on its surroundings. If a pond dries up, the
newt loses its tail fins, changes color from green to brown, and lives
in the woods as an “eft”. If the pond later fills up, the eft will go
back to the water, although it won't develop gills. These newts can
oscillate between these life styles as conditions require.
Female amphibians often lay enormous
numbers of eggs. In general,
larger species have more eggs than smaller ones, and salamanders lay
fewer eggs than do frogs. Giant bullfrogs can produce up to 20,000
eggs, while the tiny gray treefrogs will lay as few as 10. Blue-spotted
salamanders produce about 40 eggs, but spotted salamanders will lay as
many as 250. Most amphibians emigrate from the breeding ponds after
mating, leaving the eggs unprotected.
In the 1970s, concerns were expressed
about declining leopard and
cricket frog populations in Wisconsin, and in 1989, a symposium was
held in England where scientists from 63 countries shared their
research on apparent worldwide declines in amphibian populations. They
could not agree on one single factor to explain population drops but
suspected a range of causes including widespread destruction of
habitat, changing land uses, plus a number of others. Part of the
difficulty is that estimating amphibian populations is a tricky
business. Here in Wisconsin, for example, although some species are on
the decline, spring peeper populations seem stable, and wood frog
populations are even increasing. Leopard frog populations took a big
dip in the 1970s, but now appear relatively stable. Since 1981, the
Wisconsin Department of Natural Resources has coordinated a
three-times-a-year statewide frog and toad survey, sending 100
volunteers throughout the state to visit wetland sites where they
listen for and catalog calling frogs and toads.
Amphibians are the top predators in
many wetlands and along waterways,
consuming a wide variety of insects and other invertebrates. On the
other hand, amphibians are also a favored food for a variety of fishes,
reptiles, birds, mammals and other amphibians. As such, they are
important links in the food chain and we would do well to be sure
conditions remain satisfactory for their survival.
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June 10, 2008: Everyone Loves a Baby
I almost stepped on the little guy
flattened in the grass. He lay
absolutely frozen in place and only a slight movement of the hair on
his flanks proved that he was alive. The baby woodchuck could not have
been more than five or six weeks old and had no business being out by
himself, and I’m sure he was regretting his daring. Mother and the rest
of the family were watching to see what would happen from the safety of
the den under Jim’s solar kiln, and she chirped her warnings for him to
stay put. I posed no danger but certainly there were plenty of others
around that would have relished such an easy meal.
This common rodent, that is actually a
member of the squirrel family,
will grow to more than two feet in length and weigh up to 14 pounds if
he lives long enough. The woodchuck is almost a complete vegetarian,
eating leaves, flowers and soft stems of various grasses, field crops,
and herbs. It is very fond of garden crops like peas, beans and corn
and will even climb trees for apples and other fruit, and I was glad
that the den was some distance from my sprouting vegetables.
Woodchucks have burrowed under the
cement floors of the kilns to make
their dens ever since the kilns were installed, but more typically live
along the edges of wooded areas that are bordered by open land. Several
tunnels lead to an enlarged nest chamber, 3-6 feet underground, and the
main entrance is usually conspicuous because of the pile of dirt and
stones. In digging, the animal uses its strong front feet and claws
primarily, but it also moves stones or cuts roots with its big teeth.
The amount of subsoil removed in the course of digging one burrow
averages an almost unbelievable 716 pounds.
In Wisconsin, woodchucks usually
hibernate all winter, emerging around
the first week of April if the weather allows. The breeding season soon
begins and a litter of two to nine naked, blind and helpless cubs are
born in early May. Their eyes open at about 4 weeks but they seldom
venture outside until 6 or 7 weeks old. The woodchuck occupies an
important niche in the wildlife community because skunks, foxes,
weasels, opossums and rabbits all use its burrows for their dens and
the countless generations of woodchucks have contributed much to the
aeration and mixing of the soil because of the tremendous quantities of
subsoil moved.
Most of the baby animals in our woods
and fields have similar stories.
The parents – those that are active throughout the winter like the
coyote and fox, those that hibernate like the woodchuck and chipmunk,
and those who just wait out the severe weather in their dens like the
raccoon and skunk – breed as the winter storms wane and the
temperatures moderate. With the exception of squirrel kits that are
usually born high in trees, most of the young are cared for in dens
underground. Gestation is only a couple of weeks long and so the new
babies are mostly naked, blind and deaf, and are only able to pull
themselves to a nipple and nurse, and then often need their mother’s
help.
They grow quickly, however, and in a
month or so, they are venturing to
the mouth of the den and peering outside. During their first weeks, all
are fed on mother’s milk but the predator-types are quickly introduced
to regurgitated meat that the father brings back to the den, and
vegetarian mothers soon lead their young out to feed on nearby plants.
Soon the dens are abandoned, but the adolescents remain with their
parents for their education and protection – sometimes until the next
breeding season.
An exception to this scenario is the
white-tailed deer as it mates in
the fall and gives birth to one, two, or occasionally three fawns that
are fully furred and are up on their feet within minutes of their
birth. The small white spots on a reddish brown coat help camouflage
the young fawn as it lies motionless in the grass or leaves, but it can
jump up and run almost immediately to escape a predator. The spots
disappear when the fawn gets its winter coat, at about five months of
age.
As they leave the dens, all of the
various babies are cute furry
bundles with bright eyes and endearing faces. Few survive to adulthood,
however, and most become just a meal for some larger animal. Even a
quick look at the statistics indicates the logic in such a system,
however unpleasant. When predators are absent for some reason,
populations soar and the balance of nature quickly is lost to the
detriment of all. Each parent must only replace itself during its
lifetime to maintain the species, but any excess is vital to countless
other species. Still, we enjoy each baby we discover and believe it
will be the one to survive to share the bounties of our farm.
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June 3, 2008: Mosquitoes: Oh My!
According to Phil Pellitteri,
University of Wisconsin extension
entomologist, there are more than 10,000 different insects, spiders,
and related creatures that you could encounter during a summer walk in
Wisconsin. Most are completely harmless, but the less than one percent
that sometimes attack people certainly get one’s attention. Black
flies, ticks, mosquitoes, chiggers, deer flies and horse flies all
require the protein in animal or human blood to make eggs, and some
other creatures bite or sting when disturbed or threatened.
Mosquitoes have been around for 100
million years and have diversified
into 3,000 species that are very different from one another. They have
successfully adapted to climates from the arctic to the equator and
developed means of locating a blood supply in each locale. People are
never the primary prey especially in temperate climates, and the
insects prefer utilizing animals that are most abundant in their
habitat such as frogs, birds, or other animals, but they will
aggressively attack humans if they appear. Mosquitoes can sense
increases in carbon dioxide given off in mammal breath up to 100 feet
away, as well as certain chemicals in sweat. As they follow the scent,
they see only general shapes and sizes with their compound eyes, but
within 10 feet or so, extremely sensitive thermal receptors on the tips
of their antennae tell them that hot blood is on tap. The range of
these receptors increases threefold when the humidity is high.
There are more than 50 mosquito
species living in the state, and
Pellitteri contends that the most bothersome come from the genus Aedes.
These are sometimes called "floodwater" mosquitoes because if a pond or
riverbank dries up, any eggs there can remain dormant for months or
years until they are again flooded. Once the rains begin, the pests can
appear in less than two weeks, and as many as 100 mosquitoes can emerge
per square foot of water surface each day. Female mosquitoes will live
for three to six weeks and can take multiple blood meals during this
time, laying a new batch of eggs each time, and many are known to
migrate 10 to 20 miles from their breeding site in search of a victim.
Like many other insects, the mosquito
goes through four distinct stages
of its life cycle -- egg, larva, pupa, and adult. Eggs are laid either
on damp soil, as is often the case of Aedes, or on the surface of quiet
water where they float singly or stick together in rafts of a hundred
or more. The length of the egg, larval and pupal stages depend on the
temperature and species characteristics. Some will go through their
entire life cycle in as little as four days while others may take as
long as a month.
The mosquito eggs hatch into larvae or
wigglers, which spend most of
their time at the surface of the water breathing through an air tube or
siphon, but can swim and dive down from the surface when disturbed.
They filter organic material through their mouthparts for food and grow
to about ½ inch long, shedding their skin several times. On the
fourth molt the larva transforms into a pupa which will
remain in the
water another 1 to 4 days, floating at the surface and taking oxygen
through two breathing tubes. If it is disturbed it will dive in a
jerking, tumbling motion and then float back to the surface. When
development is complete, the pupal skin splits and the adult emerges,
resting on the surface of the water to allow its wings to dry and
harden. All stages are important food sources for fish and other
creatures.
While the Aedes may cause considerable
grief through their prodigious
numbers, other species are present, as well. The Northern house
mosquito, Culex pipiens, is usually the most common pest in urban and
suburban settings and is often an indicator of stagnant water sitting
around in tin cans, discarded tires and other containers. Culex pipiens
is recognized as the primary carrier of St. Louis encephalitis, a virus
found in a variety of wild birds including the house sparrow, and the
female can pass the virus from one bird to another or to a human as
well. Until the appearance of the West Nile Virus, this was the only
mosquito-borne disease seen regularly in Wisconsin and it can cause
complications in small children.
Worldwide, mosquito-borne diseases
such as malaria, yellow fever,
dengue fever, and encephalitis kill more people than any other single
factor. Mosquitoes also transmit heartworms to cats and dogs. West Nile
virus, which has been widespread in Africa, southern Europe, the Middle
East and western Asia, first appeared in the United States in 1999 and
was found in Wisconsin birds in 2001 and in humans here in 2002. The
danger is not very great as very few mosquitoes actually carry the
virus and the illness generally has mild flu-like symptoms, but in rare
cases, the virus can cross the blood-brain barrier and produce
encephalitis, a swelling of the brain and spinal cord that can be
fatal.
Mosquitoes and other flies are a vital
link in the food chain for many
creatures, but few of us have any other good words for them.
Fortunately, several excellent chemical repellents have been developed
that block their thermal receptors, allowing us to enjoy the outdoors
without too much discomfort.
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May 27, 2008: An Insect-bird Cross
Those of you who are up and about at
the crack of dawn may be surprised
to see that the hummingbirds have risen even earlier and are stoking up
at the feeders. These consistently cold mornings with temperatures
hovering close to the freezing point must be very taxing for their tiny
furnaces, and I would guess that having sugar-water readily available
is making a big difference to their wellbeing.
Hummingbirds have the highest
metabolism rate of any animal on earth --
a high breathing rate, a high heart rate, and a high body temperature
-- and to maintain all of this and to provide energy for flying they
must consume up to 3 times their body weight in food each day. Much of
their natural diet is sugar that they get from flower nectar and tree
sap, but they also eat insects and pollen for protein. A hummingbird’s
bill is long and tapered to reach deep into flowers, and its tongue is
grooved on the sides to collect nectar that it laps up at the rate of
13 licks per second. A hummingbird will feed five to eight times every
hour, and in order to gather enough nectar without human help, it must
visit hundreds of flowers every day. Just one day of very cold
temperatures or bad luck finding flowers can prove fatal.
A hummer does have an interesting way
to conserve energy when it can't
feed, such as at night or when the weather is too cold or too rainy to
fly. It enters a sleep-like state known as torpor in which its body
temperature can drop almost 50 degrees F, the heart rate may slow from
500 beats per minute to fewer than 50, and breathing may briefly stop.
When conditions improve the bird rapidly vibrates its wings to generate
body heat and warm its blood supply, and soon its body temperature
rises to its normal 102.2 degrees.
Hummingbirds are native only to the
Western Hemisphere, and you can
imagine the surprise and even disbelief of the first European explorers
when they first saw one. Early writings indicate that they thought
these fascinating creatures were a cross between an insect and a bird,
and marveled at their size, their buzzing flights, and their bright
colors that suddenly changed from dazzling to dark and back again. By
the middle of the nineteenth century there was a large market for
hummingbird skins in Europe. Hundreds of thousands of
hummingbirds were killed in South America and shipped to markets in
London and other cities, where skins were purchased for collections as
well as to make artificial flowers, "dust catchers," and other
ornaments. Native Americans also used them as decorations, as it was
reported that some individuals that met the pilgrims wore hummingbird
earrings, and soldiers and missionaries in Mexico saw Aztec kings who
wore cloaks made entirely of hummingbird skins.
The hummingbird family includes over
300 species and is the second
largest family of birds after the flycatchers. South America has the
greatest variety, with Ecuador housing 163 different species. There are
over fifty species that regularly breed in Mexico, sixteen that breed
in the United States, and four species that breed in Canada. Only the
ruby-throated hummingbird nests east of the Mississippi River, however,
although other types occasionally wander through. Hummingbirds range in
size from the bee hummingbird of Cuba that weighs about 2.2 grams and
has a length of only 2.25 inches to the giant hummingbird of South
America that weighs about 20 grams and is about 8 inches in length. The
ruby-throat weighs about 3 grams (about 1/10 ounce) and is about 3 1/2
inches from the tip of its beak to the tip of its tail.
A hummingbird has a muscular body and
extremely flexible wings with the
elbow joints very close to its body. It can rotate its wings in a
circle, a characteristic that allows it to fly both forwards and
backwards, as well as up, down, sideways, hover, or even upside down
for short distances. Ruby-throat wings beat about 55 times per second,
while other species sometimes beat up to 80 times per second, and
during courtship dives have been clocked at up to 200 beats per second.
The average life span is three to four years, although most die during
their first season. The longest known surviving ruby-throated
hummingbird was a banded bird that was 6 years 11 months old.
The highly iridescent feathers of a
hummingbird throat are among the
most specialized of all bird feathers. They have tiny sub-feathers that
are smooth and flattened and packed with layers of tiny platelets
filled with air bubbles, producing hues which are not dependent on
pigment but on interference coloration, such as that seen in an oil
film or soap-bubble. In hummingbirds, 8 to 10 such layers are
tightly stacked on top of one another and give hummingbirds the most
intensively iridescent feathers known in birds.
Each spring we eagerly await the
arrival of the birds that dine at our
feeders, and the watch is on to try once again to find one of their
nests. Perhaps this will be the year!
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May 20, 2008: A Woodland Threat
When one drives about in southern
Wisconsin viewing neatly maintained
farms, small towns with super stores and exercise studios, and along
miles of landscaped highways, it is easy to forget that the area is
only a few generations from wilderness and subsistence living. The
occasional incursion of a black bear or wolf is a stark reminder but
few of us pay much attention to such visits, and it is only when one of
the resident wild ones oversteps what we consider its proper place that
we become aware that it even exists.
A sad case in point is the loss of two
small pet dogs in an outlying
subdivision recently, as well as the attack on our neighbor’s spaniel –
all evidently the actions of local coyotes. These versatile predators
eat primarily small mammals, such as voles, eastern cottontails, ground
squirrels, and mice, but they will also eat birds, snakes, lizards,
large insects and an occasional larger animal if they can manage it.
Any unwary small dog and cat in its territory is fair game for a hungry
coyote.
A typical coyote resembles a small
lanky German shepherd, but several
characteristics distinguish it from a dog. A coyote tends to be more
slender, have wide pointed ears, a long tapered muzzle, yellow eyes,
and an straight bushy tail which is carried low to the ground. The fur
is usually a grizzled-gray color with a cream-colored or white
underside, but the color may be somewhat variable. It weighs about 30
pounds and is an intelligent, adaptable creature with many interesting
habits.
The coyote typically lives about six
to eight years in the wild but has
an annual adult mortality averaging 30-50%. It faces natural hazards
such as disease, predation, and starvation, but many die from human
causes such as hunting, trapping, and vehicle collisions. Litters are
sometimes large, but only 5-10% of pups reach adulthood. Coyotes form
loose family groups, not tight family packs like wolves. These groups
may form for short periods, then break apart as food supply
allows. Usually the animals hunt alone or in pairs, and one may
distract and chase small prey right into the waiting jaws of another.
Coyotes can run at speeds of up to 30 mph for short bursts but can
maintain a 20 mph lope for long periods.
The coyote is one of the few wild
animals whose vocalizations are
commonly heard. A typical call is two short barks and a long yodel, and
at night both male and female will give high-pitched quavering howls as
well as a series of short, high-pitched yips to keep in touch with
other coyotes in the area. Usually they call from an open area where
the sound can travel several miles. Yelping and barking are also common
sounds, and huffing is usually used for calling pups without making a
great deal of noise. The coyote's big ears provide very acute hearing,
which is vital for detecting prey and avoiding danger.
Coyotes mate in February and the
female usually digs a den or takes
over a vacant woodchuck or other animal hole for the birth of her pups.
About 60 days later, up to a dozen fully furred but blind pups are
born. At first the male brings prey back to the den, but soon both
parents must hunt to provide enough food for the growing family. At 2
½ months the pups begin to learn to hunt, and by autumn, most
are independent of their parents.
Coyotes were originally residents of
the Southwest where they inhabited
open grassland, but they have gradually moved eastward until they can
now be found across the continent. They can survive and thrive in
suburban and even urban areas as long as there is food and shelter
available. Chicago researchers studied coyote populations in a
seven-year period ending in 2007, and estimated that there are some
2,000 coyotes living in "the greater Chicago area". They reported that
the animals subsist mainly on rodents, feral cats, and small pets, and
were living largely undetected in all areas from parks to industrial
sites. As a testament to the coyote's adaptability, one coyote, dubbed
"Hal the Central Park Coyote" was even captured in Manhattan's Central
Park in March 2006 after being chased by city wildlife officials for
two days. Coyotes can breed with domestic dogs, and the pups, called
Coy-Dogs, can be more dangerous as they often have less fear of humans
while possessing the wild instincts of a coyote.
Coyote control has long been
controversial. Farmers have often urged
strong measures to eliminate livestock losses, and some sportsmen feel
the coyote is responsible for any declines in game species. But
environmentalists firmly believe that the coyotes are necessary to
preserve the balance of nature because much of their diet is made up of
destructive rodents. What is certain is that coyotes will continue to
live around us and we must adjust our actions to accommodate theirs, as
they seem quite able to adapt theirs to take advantage of any human
lapses. No food of any kind should be left out that might attract them,
and small pets should not be out-of-doors unaccompanied—especially
after dark.
We enjoy the wild side of our farm and
area, and willingly accept that
we must share it with the original inhabitants—be they coyotes, skunks,
rattlesnakes, ticks, chiggers—whatever. I must admit, however, that a
wolf or bear might give me second thoughts!
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May 13, 2008: It's No Wonder
Some of Us Sneeze!
My favorite time of a spring day, even when the temperature is barely
above freezing, is the early morning just after dawn. The birds create
a chorus of sound – so many that it is difficult to separate out any
individual. The raucous red-wing cuts through, as does the occasional
crow, but mainly it is a haphazard mixture of robin, song and chipping
sparrow, cardinal and wren making up the singers. I scan the sky for
clouds, as on the farm the weather is a major factor in determining the
day’s activities, and now that the remaining wildflowers from the sale
are snugly tucked back into the soil, the vegetable and domestic flower
gardens await.
Luckily, the plants that are now coming into flower cause me only an
occasional sneeze out-of-doors as I am not one of the 35 million
Americans who suffer from hay fever. Trees, weeds, garden plants, and
grasses release a great deal of pollen that causes problems for many
people. Pollen is an ingenious invention of the seed plants, which
first appeared over 300 million years ago. It frees them from
dependence on water for fertilization, which is needed by the
spore-reproducing plants like ferns. The tough outer wall of the pollen
grain protects the delicate male cells until the grain reaches its
proper female stigma. There it produces a tube that grows through
the female tissue to the egg and through which the male sperm cells
travel so that fertilization can take place.
Pollen grains are microscopic, and any details must be studied through
a scanning electron microscope. Each type has its own unique set of
characteristics, which means that each species or plant family can
usually be identified. This is very convenient for researchers as
pollen grains which are washed or blown into lakes can accumulate in
sediments and provide a record of past vegetation. Different types of
pollen found reflect the vegetation that was present around the lake at
various times down through the ages, and therefore the climate
conditions favorable for that vegetation can be determined.
Pollen is the sperm of the plant world. Each pollen grain contains one
or sometimes several non-reproductive cells and a reproductive cell
containing two nuclei, one of which is a tube nucleus that produces the
pollen tube and a second nucleus that divides to form the two sperm
cells. The cells are surrounded by a cellulose cell wall and come in a
wide variety of shapes. Most are basically spherical, oval or
disc-shaped but the surface may be smooth or meshed, grooved or spiny,
and may contain pores or furrows. The respiratory systems of many
people are sensitive to these, particularly those of the
wind-pollinated plants that must produce masses of pollen to ensure
that at least some of it reaches its target. Grass pollen affects about
95% of all hay fever sufferers, and birch, oak, and nettle pollen are
also well known for their allergenic properties. Giant ragweed, which
has been found to spread up to 8,000 million pollen grains in just 5
hours, is one of the worst.
The majority of flowering plants are insect-pollinated, however, and
they produce smaller quantities. As an enticement, many plants secrete
nectar, a sweet substance the insects or other creatures relish as
food. Approximately 90 cultivated crops are dependent on insect
pollination, and bees are responsible for about 80% to 90% of this
activity. As a worker bee makes her way from plant to plant, pollen
accumulates on her body and in special "baskets" on her legs that then
often rubs off onto the female parts of the next flower she visits.
This pollen is often sticky to adhere to the bodies of insects and can
form clumps making it visible to the eye, which often makes sufferers
assume that this is what is causing their symptoms. While such pollen
does have allergenic properties, the chances of it reaching the nose
are usually slim, and it is usually the wind-pollinated species with
their insignificant flowers often producing millions of pollen grains
that cause the trouble.
Plants use additional means to attract other insects such as perfume
and color. Moths and butterflies can detect odors; therefore, often the
flowers they pollinate are sweetly fragrant. Butterflies perceive many
bright colors while moth-pollinated flowers are usually white or yellow
-- colors which stand out at dusk or night -- and usually have a heavy,
distinctive fragrance as well. Bird-pollinated flowers are usually
large and bright red or yellow but need little odor since few birds
have a developed sense of smell. In the continental United States,
hummingbirds are the most common pollinators among the birds. They
prefer tubular flowers whose petals are recurved to be out of the way,
blossoms that provide support for perching, and those that are open
during the day. Hummingbirds have very good eyes and can spot a
promising red flower (or feeder) from some distance. They thrust their
long slender bills deep into the flowers for nectar, withdrawing faces
dusted in pollen.
Warm sunny days are best for pollen distribution, either by breeze or
insects, and the weather has not been too cooperative this spring. The
flowers have responded by closing their petals around their stamens on
dark rainy days, thus protecting and preserving their pollen for better
conditions. When the sun does shine, the plants will be a-buzz with
bees and butterflies and the miracle of fertilization will take place,
ensuring that a new generation in the form of seeds and then seedlings
will be created. Another growing year has begun.
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May 6, 2008: Are These Creatures For Real?
We were pleased by two long anticipated
springtime events this week. The first was the discovery of black
morels on the hillside above the wild garden, and the second was the
arrival of the first hummingbird of the season at our feeder. Hummers
have been reported in numerous spots around the state this past week
and I put out two feeders in case one happened by. There aren’t too
many sources of suitable nectar available in our garden right now and
we assume the tiny birds will be desperate for food.
I also read that a Wisconsin crane-watcher has counted eleven active
whooping crane nests so far this spring. These are the work of birds
that are members of the new migrating flock that were led to Florida by
ultra-lites in years past. Last breeding season there were three nests
with one chick surviving to make the flight south, so hopefully this
year, as the birds become more experienced parents, there will be more.
At this writing, three of the nests have been abandoned, but if the
remaining nests produce even one chick apiece, it could bring the flock
to a total of 80 cranes by autumn.
Warmer weather will be particularly welcome as I need to get my plants
out into their summer quarters. Lovely as the greenhouse appears, it
has become infested with intruders that are causing no little grief.
Slugs and sowbugs are ancient creatures that play beneficial roles in
our woods and prairies, feeding mostly on decaying plant material and
acting as clean-up crews, but in the year-around summer of the
greenhouse, they have become creaturae non grata. They have taken up
new homes in my orchid and other plant pots and expanded their diet to
include not only the plant roots but climbed up and feasted on blossoms
as well.
A slug is basically a snail without a shell. Lack of this
covering makes it more vulnerable to predators and to drying out, but
allows it to take advantage of very small hiding places such as under
loose tree bark, beneath objects lying on the ground, and in flower
pots. It moves about by gliding along on a muscular foot, which is
lubricated with a slippery mucus that reduces friction and also helps
reduce risk of injury from sharp objects. It has two pairs of tentacles
on its head, the larger two equipped with light-sensitive eyespots and
the lower set containing organs of smell. Both pairs are retractable
and can be re-grown if lost.
Each slug has a mouth on its underside containing a rough, tongue-like
organ that is equipped with many tiny outgrowths that are similar in
structure to teeth. It uses these to scrape tissue from any edible
surface on which it finds itself and one has ruined a number of my
orchid blossoms in the process. Slugs have both female and male
reproductive organs, and once a slug has located a mate it lies
side-by-side with him/her and they exchange sperm. A few days later,
both animals lay around 30 eggs, and then repeat the process about once
a month throughout the summer.
Sow bugs are tiny crustaceans that also feed on dead or decaying plants
or animals, but will eat live plants when available. They have three
body parts as do insects -- a head, a thorax and an abdomen -- but the
thorax is divided into seven separate segments and their armored
exoskeletons remind some observers of armadillos. They also have
seven pairs of legs, two sets of antennae (one prominent and the other
inconspicuous) and simple well-developed eyes.
Female sowbugs lay eggs that they carry in a pouch underneath the body,
and the hatchlings resemble adults except in size. They remain in the
pouch up to 2 months after hatching and take about a year to mature.
Sowbugs must spend bright daylight hours in damp dark hideouts because
they breathe with gills, but at night they venture out to feed. In the
greenhouse, we often find them among the roots of precious potted
plants, leaving holes in potting media and roots alike. Hopefully,
those plants that can go into the ground will soon recover, and the
others in pots will dry out to the point so that these animals will not
survive.
Our wild garden is about two weeks behind the development that we have
seen the past couple of years, so that some plants that are often
through blooming by this time are still yet to come out. Those that
have, such as bloodroot and hepatica, have lasted longer than usual,
however, and barring a sudden transition to summer, we should have
weeks of woodland flowers to enjoy yet.
After a busy month of digging and potting, the open houses are now over
for another year. We enjoyed the opportunity to see many of you again
and to share stories and wildflowers. We always welcome company,
however, so come visit us anytime and walk the trails.
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April 29, 2008: What's In
A Name?
Trout lily, fawn lily, dogtooth violet, and adder's-tongue are all
common names for a beautiful little plant in our woods, more properly
labeled Erythronium albidum. Why the fancy moniker? Many of our
wildflowers, as well as most other plants, have been given local names
through the years and in order to make some kind of sense of the
muddle, a system was adopted for accurate identification. Firstly,
Latin was used as it is no longer spoken and can be considered a
universal language. Then each individual species was assigned several
names, the first referring to the family, such as orchid, and the
second and sometimes third and fourth to specify the individual. For
instance, consider that the yellow lady slipper is Orchidaceae (orchid)
cypripedium (ladyslipper) calaeolus (yellow) pubescens (I don’t know
the derivation of this word but it tells us that the plant is the
largest of three known similar species).
Most of us use the common names, however, confusing as they may be.
Consider that trout lily. It reportedly was given that name because its
mottled leaves are speckled like trout. However, although young plants
consist of a single leaf, as they age they grow two and this led to the
name "fawn lily". (This pair of leaves inspired naturalist John
Burroughs to write, "Its two leaves stand up like fawn's ears, and this
feature, with its recurved petals, gives it an alert, wide-awake
look".) The name dogtooth violet is even more perplexing as this plant
is definitely a lily not a violet, and it is only when looking at the
plant's underground bulb can one see the resemblance to a tooth. Even
then, why pick a dog? Another name is "adder's-tongue" and it is even
harder to see any relationship between a snake's tongue and this
wildflower. It is more likely that the plant reminded European settlers
of some plant from the old country with that name. Sometimes reverting
to a Latin term makes sense.
Virginia bluebells obviously get their name from their spectacular
flowers, although they obviously are not restricted to that state.
Another common term is "cowslip" and what kind of a name is that? It
actually has its origin in the Anglo-Saxon word cuslyppe, cu meaning
cow and slyppe for slop or dung, and you will have to use your
imagination as to why anyone would so name such a lovely plant. It is
possible that the ground in which these wildflowers often grew reminded
early European settlers of pastures laden with cow-slop.
Consider the bee-balm. It is true that bees and other insects are
attracted to its flowers but the truth is that bees have trouble
getting the nectar from their deep throats and butterflies and
hummingbirds are much more likely to feed successfully from them.
Another name, "Oswego tea" refers to the use of its leaves in making a
strongly mint flavored drink, and its abundance in the Oswego region of
New York near Lake Ontario. It is also called "bergamot" from its
fragrant resemblance to the bergamot orange, although it is no
relation.
Perhaps you have wondered about naming of Solomon's Seal. In the winter
when the leaf stalk dies back and separates from the rhizome, a scar
remains which is said to resemble the seal of Solomon, king of Israel
from 961 - 931 BC. The seal was a hexagram composed of two overlapping
triangles to create a six-pointed star, commonly called the Star of
David after King David, father of Solomon. The seal became synonymous
with Solomon who reportedly used the symbol to cast away demons and
summon angels. Solomon's plume, often called false Solomon's seal, and
starry Solomon's seal are evidently named for their similar appearance
to the larger plant, although they both lack the root scars that gave
it its
name.
The trillium and all its varieties are well named as their genus name
is derived from "tri", Latin for "three". It has three broad leaves,
three petals, three sepals, three-celled ovaries and its fruit, a red
berry, features three ribs. Although there are other trilliums
(trillia?) that grow in the area, none will be confused with the
largest and showiest representative of the clan, grandiflorum, the
large-flowered white trillium. A woodland carpeted with these white
blossoms is a sight to behold.
The Jack-in-the-pulpit sports a striped green hood or "pulpit" which
curls over "Jack," the club-shaped organ at its center, supposedly
bringing to mind an old time roofed pulpit. Its tiny flowers are either
male or female and are located at the base of the “Jack”, and a
fascinating fact is that the plant’s sex depends upon its age and
conditions. If a large double-leafed female has a few bad years, the
plant will often revert to one leaf and flower as a male, while good
growing conditions can change a scrawny male into a large, multi-leafed
female. So the Jack you see today may be a Jill tomorrow or vice versa.
Shinleaf is the rather unattractive name for a lovely little plant. It
was once thought to be a cure for rheumatism and the leaves of this and
other members of its family were used as plasters for bruised shins and
other sores and wounds, hence the name. It is also called wild
lily-of-the-valley, but I much prefer the scientific name of pyrola,
rather than borrowing one from that garden flower. The leathery
rounded leaves of pyrola persist through the winter, and in the spring
each basal rosette puts up a 6” upright flower stalk. It is very
fragrant and even though the individual flowers are small, it often
grows into colonies of some size and the combined scent can often be
detected before any flowers are discovered.
All those flowers and more are on display and for sale at our final
open house this weekend. Come visit us.
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April 25, 2008: Those
Incredible Ants
Have you stepped on an ant today? Read this treatise and you may think
twice about ever doing so again – or perhaps you will stomp every one
you see as they may someday rule the world! Ants have very complex and
varied biology. They live in colonies and this means that all the
members work together selflessly for the common goal of colony growth
and reproduction. In fact, some scientists suggest that an ant colony
may be a single organism with the individual ants as its cells. Each
nest contains at least one queen and thousands of workers, all of whom
are sterile females. These workers care for the queen, enlarge, repair
and defend the colony, care for the young and gather food. Some workers
perform only one job throughout their lives while others may fill
varying needs, with no one telling a particular ant what to do.
Ants communicate by touch and smell, but instead of sniffing the air,
they use their sensitive antennae to detect and identify subtle smells.
The waxy outer surface of an ant's body contains about 25 different
hydrocarbons, each of which emit slightly different odors that provide
important information. Each ant in the colony shares the queen’s odor,
and when two ants meet, they smell each other with their antennae to
determine friend or foe. Chemical signals seem to tell each ant what to
do -- whether to stay in the nest and tend the young, build new
tunnels, forage for food, guard the nest, or follow a trail to bring
back food.
In 2001, a research group at Stanford University analyzed the chemical
content of worker ants in the Arizona desert and discovered that if
they captured and held the first ants that came out to search for new
food sources in the morning, none of the others would emerge at all.
However, if they dropped tiny glass beads coated with a chemical
extract that contained the same proportion of hydrocarbons ordinarily
present on a searcher ant, the waiting insects inside would touch the
beads with their antennae, and somehow receive the signal that would
bring them out to start work. As a control, the researchers also
dropped beads coated with extract from nest workers or nothing, but
these received no response.
A growing number of high-tech engineers are also interested in
deciphering ants’ chemical reactions and applying them to such fields
as telecommunications, computer networking, artificial intelligence and
robotics. Ant research is even being used in an attempt to unravel
secrets about the inner workings of the mind, comparing brain neurons
that individually can do little but in concert with all the others can
accomplish great things.
The largest ants are only an inch in length, but some species are
lethal. The most dangerous are the army and driver ants of tropical
forests that march around by the million, eating all the insects,
spiders, and crustaceans that are unlucky enough to cross their path.
Driver ants will kill and eat much larger prey -- even a disabled cow
or a goat if it cannot escape. Another species builds a trap that
consists of a platform perforated by holes where waiting ants hide,
jaws wide open. When prey happens by they grab it and hold it fast
until scores of other workers paralyze it with stings and dismember it.
Wisconsin ants are not really dangerous, although if you have stepped
on a hill, you probably have found dozens of stinging insects crawling
up your ankles and legs. However, they are extremely important seed
collectors and dispersers. According to detailed studies of forests in
West Virginia and New York, the seeds of no less than one-third of our
woodland wildflowers are spread about by ants, among them beauties such
as bloodroot, Dutchman's britches, trilliums, and trout lilies. These
seeds have a common characteristic – they are equipped with a treat
that no ant can resist.
Many seeds that are not carried off by the wind or attached to a
passing animal by burs come wrapped in inviting fleshy fruits. In the
case of some wildflowers, a whitish tissue that is full of proteins and
sugars is attached to the outside of their seeds. I first noticed this
on bloodroot seed upon opening a seedpod and seeing what I erroneously
thought might be emerging roots. Later I discovered that foraging ants
carry many of these seeds to their nests, where workers chew the tissue
into pieces and feed it to the growing young. They then discard the
seed itself, often carrying it off to an ant dump unharmed and leaving
it to germinate in a new location.
Ants do other strange things than disperse seeds. Some farm aphids for
their “honey dew”. Weaver ants hold their larvae in their jaws and
squeeze them expel silk to bind leaves into a nest. Slave makers raid
other nests and carry away the larvae to eat or raise to be workers.
Parasol ants raise a fungus on chewed up leaves for food. Ants are
found on every continent except Antarctica, and, despite their small
size, are believed to make up about 10% of all animal biological mass
worldwide. “Consider the ant…”
We hope to see you all at our open houses this weekend. I guarantee
ants will be here.
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April 15, 2008: Have you Hugged a Root
Today?
We are deep into dividing and potting up wildflower plants for our open
house the end of the month, and it never ceases to amaze me how varied
are the root systems of the different species. Some form masses of tiny
filaments, some are sparse and wiry, others are thick and brittle, but
they all serve two major functions – to absorb water and nutrients, and
to anchor the plant to the ground. Often we are distracted by pretty
flowers or unusual leaves and overlook a plant’s root system, but it is
important to understand what is going on underground as the roots
affect a plant's size and vigor, how and where it is likely to
flourish, and what care should be given it. Roots will generally grow
when conditions are hospitable with sufficient air, mineral nutrients
and water to meet the plant's needs. At germination, roots lengthen
downward due to gravity, and later increase in diameter. Over time,
given the right conditions, some roots can spread with sufficient force
to crack foundations, snap water lines, and lift sidewalks.
Roots typically lie deep below the surface of the soil, although this
is not always the case: in fact, the only unique characteristic of a
root is that it is the part of a plant that bears no leaves, and
therefore lacks nodes. There are three major parts of a root. The tip
is the major area of cell division and growth, and is protected by a
cap that consists of cells that are sloughed off as the root grows
through the soil. Behind the dividing cells is the zone where cells
increase in size through food and water absorption, and as they grow,
they push the root through the soil. Here are located the root hairs
that are short-lived, elongated cells whose function is to increase the
root's surface area and absorptive capacity. And finally, there is the
zone that is directly beneath the stem where cells become specific
tissues such as those that transport fluids and food up to the plant.
Many of the structures found below ground that we often think of as
roots are actually modified stems (we know they are stems and not roots
because they have nodes). Bulbs, corms, rhizomes, and tubers as such
modified stems. A bulb is a shortened, compressed underground stem
surrounded by fleshy scales that protect a central bud, such as in
lilies and wild garlic. A corm is a solid, swollen stem whose scales
have been reduced to a dry, leaflike covering, such as Dutchman’s
britches and Jack-in-the-pulpit. A rhizome is a specialized stem that
grows horizontally at or just below the soil surface that acts as a
storage organ and means of propagation in some plants. We see rhizomes
in Solomon’s seal, and bloodroot. A tuber is an enlarged portion of an
underground stem that stores food for the plant. It has “eyes”
that are actually the nodes on the stem, and each eye contains a
cluster of buds. Butterfly weed and wild quinine are plants that have
tubers.
There are other modified stems that can be found above ground such as
crowns, stolons, and spurs. A crown is compressed stem tissue
from which new shoots will be produced, and is generally found at or
very close to the surface of the soil. Hepatica, asters, coneflowers,
and many others of our perennial plants grow from such crowns. A
stolon is a horizontal stem that is fleshy or semi-woody and lies along
the top of the ground. We often call these “runners” and they form new
plants at one or more of its nodes. Wild ginger and wild strawberries
are typical of plants with stolons. And finally, spurs are short,
stubby, side stems that arise from the main stem.
I admit that the finer distinctions between these various root and stem
systems are sometimes difficult to see, but it is storage structures
that make it possible for us to transplant our wildflowers as we do.
The sprouting plants draw on their stored energy to expand the
compressed dormant cells that were produced during the last season
until displaced roots can recover and take over the job of providing
food. Many of the more ephemeral plants have a very limited time span
to grow, flower, and set seed before competition for light, moisture,
and space send them into dormancy for another year, and we try to
reestablish them in the ground or pots quickly, to disrupt them as
little as possible.
The cold wet days that have been vexing us lately are actually good for
the wildflowers, giving them time to develop roots without having to
support much top growth. One of these days, the sun will shine and the
temperatures will warm, and suddenly the wild garden will be full of
blossoms. The first hepaticas are already blooming despite the weather,
but bloodroot, spring beauties, and the anemones will soon open their
tight buds and spread their wares for bees and other insects to sample.
The variations in flower form are many -- among them bells, pendants,
slippers – and wildflowers seem to come in every imaginable shape. Mark
your calendars now to come to visit our wild garden during our open
houses the weekends of April 26-27 and May 3-4. We have ordered good
weather, and trust that the viewing will be spectacular. There will be
hundreds of potted wildflowers from which to choose for your own
gardens, and the Local Wood people are also holding field days here
that first weekend, so there will be lots of activities for those of
you also interested in managing your woodlands.
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April 8, 2008 Another Singer
The farm is our own private Garden of Eden complete with apple trees
and plenty of serpents (and yes, I know that the fruit in the original
story would not have been apples, and our snakes are not Satanic, but
you get the idea). It only lacks one thing of being perfect – it has no
water. Valleys on either side of us are blessed with springs that
generate enough flow to eventually join to become Wilson Creek, but
ours is dry. At various times, dousers have looked for water that might
be near the surface, and we even cherished a “pipe dream” of building a
dam across the bottom of the middle field and putting a windmill over
the old well at the upper end to pump water for a pond. Nothing came of
either of these ideas, but we did eventually get water on a very
limited scale.
Our first pond was little more than a puddle off the side porch of the
farmhouse, but for 20 years, it and its subsequent versions, have
attracted birds and other creatures in our yard to drink. I dug it by
hand originally and lined it with a plastic sheet, and now it houses
water lilies and blue flags and is a joy much of the year. A small
waterfall created by a recirculating pump not only provides a shower
for bird visitors but makes music for our ears. We later put in a
larger pond in the wildflower garden, and except for the renovating
sessions that have occasionally been necessary, both ponds have proved
very successful.
Having water brings an unexpected pleasure in the early spring, and
last Thursday evening I heard the first songs of the spring
peepers. These are small brown treefrogs, the largest only an
inch and a half long, that can be easily identified by the dark "X" on
their backs. One fascinating thing about these frogs is that they
survive the winter as chunks of ice. As the temperature drops, the frog
drifts into a deep hibernation, its breathing and heartbeat stop, and
as much as 65% of the water in its body gradually crystallizes into
ice. Glucose in the cells seems to act like antifreeze to prevent
damage even though its body temperature can drop to as low as 20*F, and
when spring finally arrives and the ice melts, heartbeat and breathing
return, and the frogs make their way to any nearby water to breed.
Frogs, toads, and salamanders are amphibians, cold-blooded animals with
backbones that live part of their lives in fresh water and part on
land. They are unlike fishes in that most types have legs instead of
fins and generally breathe through lungs and skin instead of gills.
They are different from reptiles because they lack a scaly covering and
are able to take in water and oxygen through their moist, supple skins.
Because their natural environments are streams, marshes, and low-lying
meadows, these fascinating creatures are scarce in our high-and-dry
hills, but a few species have flourished since we built our two ponds.
Spring peepers, an occasional leopard and green frog, and toads migrate
to them each spring to find mates and lay their eggs, singing all the
while.
The spring peepers leave their woodland hibernation sites in late March
or early April and perch on grasses and sedges at the edges of both
ponds. The sound can reach deafening levels, far out of proportion to
their tiny bodies, because of the remarkable air sacs on the floors of
their mouths. These sacs act as resonators when they are expanded, like
the hollow body of a violin, and, by