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Rh wormy apples and pears, but the curculio, a weevil beetle, punctures the skins of plums, cherries and peaches, and pushes an egg down to the stone. The currant worm strips the bush fruits of leaves. The slug of the saw fly destroys roses, and little, green, plant-lice, or aphides, suck the juices of rose bushes, fruit trees and hop vines.

Cotton-boll weevil; first figure showing insect at rest and second showing wing-covers lifted and wings extended for flight.

Cotton plants have three enemies—the cotton-boll weevil, the cotton worm, hatched from a moth egg, and the cotton stainer, a little red beetle. The chief enemy of corn is the cut worm. The army worm marches from field to field, millions strong, destroying grasslands. Grasshoppers come in clouds and leave bare fields behind them. On the bark of fruit trees a leech of an insect sucks unseen, under the black speck disc of the San José scale. The tree dies and the pest spreads through an orchard. The tent caterpillars often take entire limbs of fruit and shade trees. They weave a cob-web tent over a big colony of squirming leaf-eaters.

The number of species, or kinds of insects is far, far beyond all other living creatures put together. Some scientists say there may be a million species. They all lay countless eggs. One scientist says that a young cherry tree may have ten million plant-lice on it. In one year the codling moth has put worms into ten million dollars worth of apples, and the Hessian fly has destroyed one hundred million dollars worth of wheat in our country. All the insect pests put together cause a loss on our farm crops, orchard fruits and garden products of five hundred million dollars in some years.

Isn't it a wonder they leave anything at all for human beings and the higher animals to eat? Farmers and gardeners fight these enemies all the time. They spray plants and trees with poisons. They plow land in the fall, to turn up buried cocoons to the frost. They plant trap strips to catch the larva, and burn the strips. In gardens they pick off grubs and caterpillars by hand. They cut