Forest Preserve District of Cook County, Illinois
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Spider Webs
Nature Bulletin No. 165   October 18, 1980
Forest Preserve District of Cook County
George W. Dunne, President
Roland F. Eisenbeis, Supt. of Conservation

SPIDER WEBS
This is Spider Time. Now they appear to be most numerous and busy at millions of spiderlings that climb to high perches and spin long filaments of silk by which they are wafted aloft on currents of warm air and may be carried hundreds or thousands of miles. Probably that is why there are spiders on lonely Islands, deserts and almost every part of the world except mountain tops and arctic regions. When we walk through a woodland these days, cobwebs, strung from tree to tree, cling to our faces. In the mornings, on lawns and sparkling with dew drops, we see dozens of filmy handkerchiefs spun by grass spiders. In gardens and fields we see the marvelous webs of orb-weavers.

There are at least 2000 species of spiders In this country but only a few families of them build elaborate webs. In each family the females construct a distinctive type of web and there are four general types: orb webs, funnel webs, sheet webs, and the irregular festoons built by house spiders. All of them are built for a purpose: as traps to catch insects.

One of the truly wonderful performances by any animal is the intricate web constructed with geometric precision by the big black-and-yellow garden spider -- one of the orb-weavers -- and If necessary she can complete it In one hour.

Although the garden spider has eight eyes, she builds a web almost entirely by touch. Underneath her abdomen are six spinnerets that can be extended or compressed and used like the fingers of a human hand. Each spinneret has "faucets" and "spools" connected by tiny tubes to several types of glands. Each type manufactures. In liquid form, a different kind of silk. Filaments of the several kinds are used singly or in combinations for specific purposes In certain locations. Most strands are composed of more than one filament. They solidify and become stronger than steel when drawn out and exposed to the air.

The sheetllke webs that sometimes appear overnight on lawns and meadows, especially in autumn, are built by the funnel-web or grass spider. Each sheet extends outward from a funnel-like opening beneath which the spider lurks in waiting for grasshoppers and other insects that may alight upon It. She constantly enlarges the web and. If undisturbed, it may become a square yard In area. In autumn, after laying eggs In one or more sacs that are hidden In secluded places, she dies. The spiderlings emerge in spring and their delicate webs may be seen in May.

The common house spider is detested by housewives because it sometimes spins a web near the ceiling in a corner of some room or closet. Generally, however, they frequent dark less-used places such as attics, cellars, barns, sheds, or under porches; and are useful as destroyers of flies, mosquitoes and moths. A typical web, usually built at night, has a central sheet of densely woven silk which serves as a hiding place and is anchored by numerous guy lines that are long and strong. This spider is one of the large family known as the comb- footed spiders. On each of the hind pair of legs they have a row of curved bristles used to fling strands of silk over any insect that blunders into the web and render it helpless. They have been known to capture, kill, and suck the body liquids from a baby mouse.

In autumn, most of the gossamers In fields and drifting through the air were spun by the tiny Balloon Spiders. Sometimes, borne away by those streamers, they are found far above the clouds or far out at sea.

Threads of gossamer, threads of life, fairy bridges by a spider's wife.


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