Forest Preserve District of Cook County, Illinois
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House Spiders
Nature Bulletin No. 206-A   November 13, 1965
Forest Preserve District of Cook County
Seymour Simon, President
Roland F. Eisenbeis, Supt. of Conservation

Nothing humiliates a housewife more than to spy a dusty streamer of cobwebs dangling from the ceiling when she has "company". With a cloth on the end of her broom, or a vacuum cleaner, she wages continual war on spiders. The spider itself frequently escapes by darting into a hide-away or dropping by a thread of silk to the floor where it may play "possum" until things have quieted down. But in basements, in unused rooms, in attics, between windows and screens, beneath porches, and in garages or other out buildings, many small spiders live their interesting lives.

Several kinds live in and around dwellings but most common of them all, in almost every part of the world, is the House Spider. It tirelessly spins webs in the corners of ceilings and walls, and under furniture -- webs so fine as to be invisible until coated with dust or soot. These webs are made of crisscrossed lines of sticky silk anchored at the ends and to each other so as to entangle any fly, mosquito or moth that comes near. The spider hides in a crevice or in a little tunnel of silk. As soon as a fly touches the web, the spider runs to it, flings silk over and around it with special combs on the hind pair of her eight legs, stabs it with her tiny poison fangs, and then injects digestive juices. When these juices have liquefied the fly's insides, she sucks it dry, leaving only the empty shell, legs and wings.

The house spider is dusty brown with several darker chevron markings on the upper and lower sides of its abdomen. The female's body is about 1/4 inch long with moderately long legs. The male is smaller. They mate in spring and Mr. Spider soon dies or is eaten by his wife who, 6 to 8 weeks later, lays from 50 to 200 small eggs enclosed in a brownish pear-shaped cocoon hung in the web. The young hatch in about a week but remain inside the cocoon until after they first molt (shed their skin). Then they emerge to remain in their mother's web until after their second molt. Meanwhile, in the cocoon and in the web, they prey on each other. Only the most vigorous survive. After that, each spins its own web and goes through 3 or 4 more molts before it is fully grown.

The Squint-eye Spider, one of the sheet-weavers, also lives in buildings, spinning large loose irregular webs in cellars and closets, or under porches, shelves, and other places where the light is dim. It has a slender, pale brown body about 1/4 inch long, and such long, incredibly slender legs that it is often mistaken for a daddy-long-legs. The mother carries the eggs in a thin transparent cocoon until the young come out. She sits head down on the web and, by jumping up and down, shakes it to further entangle insects that blunder into it.

In dry sunny places such as porches and window casings, and on the walls of houses, we find the Jumping Spider, which is gray or black, mottled with white bands and dots. They are hairy and have short legs. These spiders spin silk and are usually responsible for the cobweb that dangles from a ceiling, but make no web to capture their prey. Instead, they seize an unwary insect by jumping on it or leaping into the air after it. The male courts the female by putting on an elaborate leaping swaying dance.

All spiders have fangs and small amounts of poison, but in this region, the female Black Widow Spider is the only one dangerous to humans and it is rare in the northern states. It prefers damp dark places, such as under boards or in cellars. The body is black with an orange or red mark, shaped like an hourglass, on the under side of the abdomen.

Uncle Pete, who never married, claims the main difference between a woman and a female spider is that spiders have eight legs.

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