RELATIONS TO MAN. The economic status of the group is difficult to decide. The damage which they do to human beings in one or another of very many direct and indirect ways is enor mons, yet they are also beneficial to man in litany other ways. Perhaps the most pronounced benefit derived from insects is in the cross-fer tilization (q.v.) of cultivated crops. Without their agency in this direetion the cultivation of many useful plants would practically be impossi• ble, while in others the results ohtained at present would he impracticable. The benefits derived from individual species—such as commercial silk from the silkworm. honey from the honey-bee, shellac from the lae-insect, cochineal from an other se:Ile-insect—are well known, and the functions of insects as soil-makers, and of thou sands of the parasitic forms as destroyers of noxious insects, are most beneficial to the human species. 7t is as destroyers of cultivated crops, however. that insects are most commonly known, and it been estimated that in the 'United States agriculture and horticulture suffer an annual loss of $300,000,000 from their work. Almost every cultivated crop has not only its thousands upon thousands of individual insect enemies, but is affected by scores and even hun dreds of species. A tabulation of the insect enemies of the apple already recognized in the United States shows 281 species, of clover 82 species, and of so new a crop as the sugar-beet 70 species. The insects of the vine or the orange, of wheat, and in fact of all of the prominent staples, show equally startling figures. It is this damage done by insects injurious to agriculture that has given rise to the compara tively new branch of applied science known as economic entomology, which, although origi nating in Europe, has been encouraged to such an extent in the United States, owing partly to the greater necessities of a new country and partly to the practical turn of mind of the American, that there are more official economic entomologists employed by the States and by our general Government than in all of the other countries of the world together.
Aside from cultivated crops there is hardly any product of man's is not dam aged directly or indirectly by insects—the tim bers of dwellings, household utensils, clothes, nearly everything used as food, hooks, furniture, and drugs, and an infinite variety of other use ful substances. They are very injurious to live stock and other animals; practically every species of animal which has become domesticated and is of value to man possesses its insect para sites and enemies. Some of them are general parasites of warm-blooded animals; others are specific to the animals or groups of animals which they affect. Horses, cattle, and sheep all have insect enemies which are not only very deleterious to their health, but frequently cause their death in numbers. The bot-fly of the horse lives in the larval condition in incredible num bers in the stomach and intestines of the horse. The bot-tly of the ox lives, in the larval stage, under the skin of the backs of cattle, and by its perforations ruins their hides for commercial use. The hot-fly of sheep inhabits the nasal and orbital sinuses of sheep and produces insanity and death. (See BoT.) The horn-fly, the numer ous gad-fly. including the tsetse-fly of Africa, the screw-worm fly of the Southwestern United States (qq.v.). and many others, seriously hinder the efforts of the owners of live stock.