number of allies among the insects themselves, the helpful forms who destroy those who are noxious or mischievous.

325. Economic entomology.-The enormous number of insects which feed on useful plants gives this branch of science a great practical importance. Most insects feed on plants, and those cultivated by man seem to be especially chosen. This is due to the great masses of the same species brought together in cultivation. An apple orchard of 300 acres in New York gives opportunity for the breeding of enemies of the apple. A 3,300-acre vineyard in California breeds in numbers the insect enemies of the vine. The great orchards and gardens may be compared to bounteous feasts, and the insect guests come in families and remain until the feast is over.

Probably half the insect species inhabiting the United States (upward of 60,000 in all) are injurious to vegetation. There is scarcely a plant, wild or cultivated, that does not harbor insect pests, there being on an average six insect enemies to each species. In Europe 500 species are said to attack the oaks, and 400 species the willows. In America 250 species feed in one way or another on the apple.

Of each species the number of individuals is enormous, for most of them are excessively prolific. Of aphides or plant lice there are 12 generations in a year; 12,000,000 aphides have been found on a single cherry-tree. The grape-destroying insect phylloxera was first discovered in New York in 1854. It was carried to France in 1863, and in 1879 the valuable vines on 3,000,000 acres in France had been destroyed by its root-attacking larvæ.

326. Orchard pests.-In 1878 the "cottony-cushion scale" was brought to California from Australia on an orange-tree. In less than ten years almost every orange-tree in California was attacked by it, and the industry seemed doomed to destruction. The pest was checked by the introduction of its natural enemy, an Australian lady-bird beetle, called

Vedalia, equally prolific and quick to spread from tree to tree.

The so-called San José scale, long known in California, but probably introduced from Asia, is now the worst pest of the orchards of the United States. It is found in 35 States, and in most of these statutes exist aiming at its suppression.

327. Amount of insect destruction.-In 1864 the loss of wheat and corn in Illinois caused by the chinch-bug amounted to $73,000,000. In 1874 the total loss in the United States amounted to $100,000,000. In 1874 the Rocky Mountain locust destroyed in the States between the Missouri River and the Rocky Mountains crops amounting to $100,000,000.

From 1864 to 1878 the cotton-worm in the Southern States destroyed each year $30,000,000 worth of cotton. The Hessian fly has often destroyed $50,000,000 worth of grain in a single year in the United States. Ten per cent. of the field-crops of our country are each year by noxious insects. The annual loss from this source has been calculated to be $300,000,000.

328. Prevention of insect ravages.-These ravages can not be prevented, but they can be materially checked. A few examples of insect fighting may be given:

The cottony-cushion scale was virtually exterminated by the introduction of its enemy at home. This can be done with various other species.

In Indiana the destructive corn-root worm was destroyed by rotation of crops, introducing something on which the larvæ could not feed.

Many insects are killed by insecticides, washes, and sprays, or by fumigation with gas. The Department of Agriculture maintains a division devoted to insect fighting. It costs now about $75,000 a year, and saves the farmers and gardeners many times that amount.

The preservation of insect-eating birds is an effective method of insect fighting.

329. Beneficial insects.—Many insects are useful from their habit of devouring the noxious species. The ladybird beetles feed on scale-insects and plant-lice. The ichneumon flies lay their eggs in the larvæ of many species. The carrion-beetles and others are valuable as scavengers, as are various flies.

330. Animals as servants.-As servants of man, the horse, the donkey, the ox, the goat, the dog, the elephant, the camel, the llama, the reindeer, the buffalo of Europe, the water-buffalo of the East Indies, have been with him from the dawn of history, and the help they render needs no description here.

331. Animals as friends. In the category of higher service to man, the service of friendship, the dog stands nearest. The cat always thinks of herself first, but the dog will lay down his life for his master, or even for his own feeling of duty. The monkey is devoted to his own kind, and may be equally devoted to his master, while his thoughts and disposition run in closer parallelism. But the monkeys for the most part are subject to violent fits of passion over which at the best they have little control. The anger or jealousy of some of the larger monkeys is often dangerous to human life. For this reason men have rarely admitted monkeys to their circle of personal friends. In some respects the gentle, wistful little marmosets of South America constitute an exception to the rule of quick temper among monkeys. To the circle of personal intimacy the dog can often rise, and the horse also so far as he can understand.

Other friends of man are the singing-birds, those who can be happy even though caged. Easily first of these is the mocking-bird. The bobolink, most joyous of birds, the nightingale, sweetest of all singers, the wood-thrush, and the skylark can scarcely be reared in cages. Other attractive cage-birds are the cardinal grosbeak, the canary-bird, the Japanese finch, and the many species of parrot, who use

their hours of loneliness in human society by picking up and repeating the phrases they hear. They show a skill in imitation and a capacity of association of ideas unequaled by any other of the lower animals. In Japan certain kinds of chirping insects, cicadas and the like, are kept in cages in homes, affording great delight to their owners.

CHAPTER XXVIII

THE ANIMALS OF THE PAST

332. Extinct animals—The mammoth. —The animals alive to-day are but the merest fraction of all that have been. New species of animals long since vanished from the face of the earth are continually being discovered. Notable among fossilized remains are those of the mammoth, an enormous elephant, specimens of which, not even decayed, have been found frozen in the ice of northern Siberia. Some of the specimens discovered were complete with skeleton, flesh, and hair. Its like exists no longer. It resembled an elephant much more than any other kind of living animal, but it was twice the bulk and weight of the largest

living elephant and a third taller. Its body was covered in places with a brownish wool, in others with long hair. Bones and other remains of many mammoths have been