BRINGS NEW QUESTIONS
by Whit Gibbons
November 18, 2007
many changes, and ecological questions. The following are about a common
caterpillar most people see at this time of year.
Q - What
are these furry little bugs called woolly bears that I see crossing the
highways in the fall? I've heard you can predict how cold the winter is
going to be by the width of their bands.
bears are the caterpillars of the Isabella tiger moth, which is a yellowish
moth with a wingspan of about two inches. The caterpillars attract more
attention than the moths because they are indeed an insect we see as it
crosses roads. They have fuzzy looking bristles that are arranged in three
bands--a black one at each end and a brownish orange one in the center.
The size of the bands varies among individuals, and one superstition is
that the width of the middle band indicates whether it is going to be
a cold or mild winter. I'm not sure which width is supposed to indicate
a cold winter, but it does not matter since woolly bears are no better
at giving long-range weather forecasts than the Farmer's Almanac or the
National Weather Bureau. As far as the bristles go, woolly bears are completely
harmless (except to the rare person who happens to be allergic to them)
and can be picked up. In fact, I like picking up woolly bears because
they roll into a neat little fluffy ball.
Q. - I know
what a woolly bear caterpillar looks like, but what are they doing roaming
around before it gets cold every autumn? Where are they going?
A. - When
they are moving in the fall, they are probably looking for a place to
bed down for the winter, or if it is still warm, looking for more plant
material to eat. Caterpillars of some moth species turn into pupae and
form cocoons before it gets cold, but woolly bears stay caterpillars all
winter. Entomologists (scientists who study insects) have actually found
that woolly bear caterpillars are able to withstand freezing temperature
by producing a substance in their bodies that acts like antifreeze. When
warm weather arrives in the spring, the caterpillars begin eating again
and soon turn into pupae that form cocoons. In a couple to three weeks
the moths emerge and are active in the summer. A question entomologists
don't know the answer to is, how do woolly bears always know to cross
perpendicular to the road, which is always the shortest distance to the
Q. - Are
these orange and black caterpillars I see on the highway nearly every
fall one of the stinging kind I have heard of? They seem to be pretty
bristly. Would it be safe to pick one up?
A. - A few
moth caterpillars indeed have bristles that are hollow tubes containing
venom that break off in the skin and can be very painful. At least one
instance of a recorded death in the United States, a little girl in Florida,
has been recorded from the sting of several saddleback caterpillars, a
species which has such venomous spines. The Io moth has a pretty, greenish
yellow caterpillar, with red and white stripes on the side, and the male
turns into a large and beautiful yellow moth with huge circles on the
wings that look like eyes. The female Io moth is brownish without the
eyespots. Despite its elegant appearance the Io moth caterpillar is a
stinging species. Most caterpillars that have ornamental spikes and spines
that are very conspicuous are actually not venomous. But by appearing
formidable they probably avoid being eaten by some predators that would
like a tasty caterpillar meal. Woolly bears are bristly but they do not
have the venomous kind.
Q. - What
states are these so-called banded woolly bear caterpillars found in? I
saw them in the fall when I lived in the Midwest and now have seen them
after moving down South.
bear caterpillar larvae and their tiger moth adult stage are found in
virtually all of the continental United States. They even range into Canada
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