- Published: 26 May 2009
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Anita Barnes, Age 12, Of Houston, Tex., for her question:
How long do locusts stay under ground?
Locust plagues have pestered our crops since the time of the early settlers. Some people claim that the hungry insects strike every year. Others claim that they stay underground and take to the air after two to 20 years. Part of the confusion lies in the fact that all the insects we call locusts are not true locusts.
The true locust belongs to the grasshopper group of insects. He starts life as an egg buried in the ground or in a log of rotting wood. If the weather is warm, in a few days he may hatch into a miniature, wingless copy of his parents. He starts his hungry career at once by devouring the greenery around him. The youngster is called a nymph, and, as he grows, the nymph sheds his old coat for a bigger one.
In three months or so, the locust nymph molts four or five times and, at last, emerges as an adult winged insect. If the eggs are laid in late fall, they may not hatch until spring. In this case, the unborn locust stays in the ground all winter, but no longer. The adult locust, like all the grasshoppers, is a champion jumper. He is also a splendid flier. When he takes to the air, he spreads out his gauzy underwings like a pair of fans.
The true locusts damage our field. Crops. But the so called 1-year locust belongs in quite a different insect group. This fellow is actually a cicada, a relative of the grasshoppers, the aphids and the scale insects. Altogether there are 2004 or more different types of cicada, and almost 200 live in the United States, each with its own notions of when to leave the ground and take to the air.
The mother cicada lays her eggs in the bark or near the end of the twigs on trees and branches. Each egg hatches into a wingless, scaly nymph, who promptly drops to the ground and digs himself into the dirt. There he lives for years sucking juices from the roots.
The cicada nymph may stay underground from four to 20 years, depending upon the species to which he belongs. At the right moment, it emerges with countless numbers of its relatives and climbs up a tree trunk. Its skin cracks open and out steps the grown cicada. It is a large and beautiful insect with gloving red eyes and wide gauzy wings. They flock through the summer air with a noisy din for two weeks or so. By this time, the new broods of cicada eggs are laid, and the parent insects perish.
The mother cicada, weakens the twigs where she lays her eggs and the young nymphs sap underground roots. They are destructive insects, but not so bad as the plagues as the true locust. Flocks of these insects cloud the sky as they migrate for food. When they descend, they devour every green leaf in sight. The ground is stripped of crops and grasses, and the trees lose all their foliage.