Forest Preserve District of Cook County, Illinois
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Water Bugs
Nature Bulletin No. 221-A    March 12, 1966
Forest Preserve District of Cook County
Seymour Simon, President
Roland F. Eisenbeis, Supt. of Conservation

WATER BUGS
It is fascinating to lie in a boat or on a log at the edge of the water and watch the drama that unfolds among the small water animals. Among the star performers in small streams and ponds are the Water Bugs. These are aquatic members of that large group of insects called the "true bugs", most of which live on land. Moreover, unlike many other types of water insects, they do not have gills but get their oxygen directly from the air. Those that do go beneath the surface usually carry an oxygen supply with them in the form of a shiny glistening sheath of air imprisoned among a covering of fine waterproof hairs. The common water insect known to small boys at the "Whirligig Bug" is not a water bug but a beetle.

All kinds of water bugs have needle-like sucking beaks with which all, except the Water Boatman, attack and feed upon other small water animals, and upon insects which fall in the water from overhanging vegetation. With these sharp beaks they can inflict painful stinging bites through the tough skin of human hands. Some kinds dive or swim. Others prowl among underwater plants and trash. A few ride the surface film. Water boatman, in contrast to the others, feed mainly on vegetable ooze, algae, and the like.

Young water bugs are much like their parents, only smaller. For instance, young Water Striders look like frisky little spiders. All kinds spend the winter as adults. Some hibernate in underwater nooks, while others remain rather active. They regularly live a year or more. When the ice begins to melt in spring they are often the first active water creatures seen.

The largest of all the diving and swimming bugs are the Electric Light Bug -- so called because so many of them used to fly to the old- fashioned arc lights -- and the Giant Water Bug; both wide flat-bodied insects which may reach a length of 1-1/2 or 2 inches. Both have the front legs fitted for clutching and the other two pairs flattened and oar- like for rapid swimming. They devour dragon flies, and often attack and kill minnows, small frogs and tadpoles. The female of the Lesser Water Bug, instead of fastening her eggs to plants like most of the others, glues them on the back of her husband, often in spite of his vigorous opposition.

Most conspicuous and commonly known are the Water Striders or Water Skaters. These ride on top of the water, with only their feet making dimples in the surface film. They have very long legs and slender bodies, like boats with long oars. They skip about rapidly on the surface but are practically helpless on land. Of the several kinds, some have short wings -- others none at all. One small species prefers rapid water where it uses an oar-like fan of bristles on the middle leg to swim against the current.

The little Water Boatmen, being vegetarians, spend much of their time on the bottom. Their long oar-like hind legs are flattened for swimming and diving but they also fly well. The females of some kinds lay their eggs on the backs of crayfish. The Backswimmers are similar to the water boatmen except that they commonly hang head- downward from the surface and always swim on their backs. The male can make a squeaky noise by rubbing its face with its front legs.

The Water Scorpions have two long tail filaments, like a snorkel on a submarine, through which they breath as they lurk beneath the surface, waiting for the aquatic insects, snails and small crustaceans upon which they prey. The long slender stick-like Marsh Treaders, or Water Measurers, walk slowly over the water plants at the edges of ponds, as if measuring each step.

Signs of spring: skunk cabbage and water bugs!


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