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Tiger Beetles -- The Bushwhackers
Nature Bulletin No. 459-A   May 27, 1972
Forest Preserve District of Cook County
George W. Dunne, President
Roland F. Eisenbeis, Supt. of Conservation

TIGER BEETLES -- THE BUSHWHACKERS
While walking along a dry forest path you may see a flash of brilliant green: an insect that may alight, facing you, some twenty feet ahead. If you can creep close enough without starting it, you will discover that it is a Tiger Beetle -- the kind that frequents woodlands -- with shiny metallic-green wing covers, large eyes, long slender antennae or feelers, and long sharp-toothed mandibles.

The tiger beetle is a hunter. It hides like a bushwhacker and feeds on flies, other beetles, small grasshoppers and, sometimes, crickets. It can fly as swiftly as most of the fleeter insects and, with its powerful jaws, seizes its prey which is then dragged down into the bushes. There the tiger beetle proceeds to drink the blood of its victim, after the fashion of a weasel. Only the empty carcass is left and the bushwhacker soon goes hunting again. It is among the most rapacious and greedy of insects -- it is a "tiger ".

The adult female searches for a bare area of ground depending upon which kind she is. There she digs a narrow shallow hole with the help of two sharp little horns, called oviposters or egg placers, attached to the rear end of her body. Then she lays an egg. That is the first stage of the life cycle.

When the egg hatches, a larva comes out. The larva, sometimes called a "doodlebug", enlarges the egg hole to make a burrow from 4 inches to a foot or more depth, slantwise in the ground. When hungry, which is nearly all the time, the larva crawls to the mouth of the burrow and lies there like a sniper -- with his massive head raised slightly above the surface -- waiting for a victim. When some unwary insect comes close to the burrow, the tigerish larva throws its body forward and, with its strong mandibles, seizes the prey which is then dragged to the bottom of the burrow where a leisurely dinner can be enjoyed. On the back of a tiger beetle larva there is a small hump equipped with two stout curved hooks. Should a too-strong victim try to pull the larva from its hole, these hooks are stuck into the side of the burrow like an anchor.

After about a year the larva digs a side room in the burrow and there it goes into the third or pupal stage. The adult tiger beetle emerges in autumn, hunts insects -- if a female, it also lays eggs, then it digs a hole in the ground where it spends the winter. This is the fourth and last stage of the life cycle.

More than two thousand species of tiger beetles have been recorded from all over the world. Nearly two hundred of these are found in North America where they range well into Canada. In addition to the green forest tiger beetle, there are two other species most commonly found in the Chicago area. The black-brown tiger beetle is often seen in vegetable gardens, going between rows of carrots, beets or other crops, in search of insects to eat. The white-lined gray-brown tiger beetle is found on river or creek banks and the shores of lakes.

The tiger beetles are usually regarded as beneficial insects because their feeding habits include the capture and eating of many insects harmful to economic food crops. Their stylish coats of black or bronze or metallic green, banded or spotted with white or yellow, arouse our admiration.

Remember -- all that glitters is not gold, it may be a tiger beetle.


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