Nature Bulletin No. 238 October 2, 1982
Forest Preserve District of Cook County
George W. Dunne, President
Roland F. Eisenbeis, Supt. of Conservation
With the coming of October and its chilly nights, all cold-blooded
animals become numb or sluggish except during the middle of the day
when the warming sun rouses them to wakefulness and quickens their
movements. Insects and spiders, especially, seem to sense that their
time is short and that they must prepare for winter or have a final fling
in the sunlight before they die.
stones and fallen logs, caterpillars are busy building cocoons,
and spiders are making silken tents and cocoons in which they lay
masses of eggs. The mud-dauber and yellow-jacket female wasps, and
the blow flies, crawl between the screens and windows of our houses
seeking warm protected places, and field crickets invade our
One of the best known of all autumn insects is the Wooly Bear
caterpillar of the Isabella Tiger Moth. It is closely covered with
rosettes of bristly hairs, like an evenly-clipped coat of fur and.
according to legend, the kind of winter we will have is foretold by how
much of its two ends are black and how much of Its middle is reddish
brown. At this season it always seems to be in a hurry -- scurrying
across roads, sidewalks and bare places -- hunting a protected place
where it may curl up and hibernate. It often wakes and crawls about on
warm winter days and it Is one of the earliest signs of spring.
In late summer, large green katydids hidden among the leaves of trees
and vines sang their melancholy choruses from dusk until dawn. Now,
on mild evenings, only an occasional one is heard rasping hoarsely.
Presently a hard frost will kill the last one and only their eggs buried
in soft bark will survive to produce next summer's katydids.
In the fields on warm days we hear the songs of other kinds of
katydids. Down amongst the grass, fallen leaves and around buildings,
male crickets of several kinds chirp both day and night. They sound
like the string section of an orchestra: some shrill and twittering; some
strumming in sedate cadences; rarely, the deep froggy chirps of a
mole-cricket. However, as it becomes colder during the night, their
voices change like those of boys who are just beginning to shave -- the
chirps are pitched lower and occur at longer intervals.
The grasshoppers are active only in daytime. On fall mornings they
may be found clinging to a weed or grass stem, or on the ground --
stiff with cold. Later they crawl slowly to the top of the weed, or onto
warm stones and pavements. or up on the sunnysides of trees, fences
and buildings where they soon become active enough to jump or fly.
An afternoon walk across a meadow is often like a boat trip across a
lake, with waves of grasshoppers flowing away on either side. Only
their eggs, laid in the ground, survive the winter.
Wild fruit of many kinds -- grapes, cherries, plums, haws, crabapples
and elderberries -- still hang dead ripe and sweet, or lie crushed and
fermenting on the ground. These attract hordes of butterflies, moths,
wasps, bees, ants and flies. The Red-spotted Purple and the Violet-tip
butterflies are most common, sipping juice through their long tongues
as they slowly open and close their wings. Whole processions of ants
carry juice and bits of fruit back to their colonies, and there are
swarms of many kinds of flies. Most numerous are the large loud-
buzzing Blue Bottles and clouds of the tiny, gnat-like, red-eyed Fruit
There's a lot to see and hear if you take a walk on a sunny autumn day.
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Update: June 2012