INSECTS OF IMPORTANCE TO MAN. Startling as it may at first seem, it is nevertheless a fact that insects comprise the largest group not merely of all land animals but of all living creatures. The late C. V. Riley, curator of insects in the United States National Museum, estimated that the world's insect cen sus contains 10,000,000 species. Later estimates, however, considerably reduce this number but the most conservative figure is 2,000,000 of which more than 350,000 have been named and described, including more than 25,000 native to North America. These latter figures are being increased at the rate of several thousand an nually through the taxonomic work of entomol ogists.
Since the habits of insects vary widely it is natural to expect to fund many species that directly or indirectly affect human interests. Of these the most useful are those (1) that fer tilize the flowers of plants whose fruits or seeds or the crops grown from these are employed by man for food or other purposes; (2) those that manufacture or secrete or whose bodies consti tute products similarly utilized; (3) those that prey either as parasites or predaceous enemies upon other insects or animals which destroy cultivated plants orplant products, domestic animals or their products; (4) those that act as scavengers of dead animal and vegetable matter, including the excrement of other ani orals; (5) and those that directly or indirectly change the character of the soil in which they pass at least part of their life history.
The first group includes a great many minute and a smaller number of large sized in sects that affect man little or not at all in any other way. Were it not for them, very few plants, as Darwin and other noted investigators have proved, would form seeds or bear fruits. Most conspicuous perhaps of all these is the blastophaga or fig-wasp, upon Which the caprification or fertilization of the Smyrna fig depends and for lack of which this choicest of all figs has until very recently failed to set fruit in America. Most con spicuous in the second group are bees which, according to Herrick, are kept by 3,000,000 beekeepers in the United States and yield honey to the value of over $25,000,000 annually — $2,000,000 in New York State alone. These insects also supply large quantities of beeswax which is used in the arts. In the second group are also the scale insects which supply certain fine waxes, cochineal, lac and its accompanying purple dye and some other ma terials. In the third group (predaceous and para sitic insects) are countless species belonging to the orders Hemiptera (for instance, assassin bugs and water striders), Neuroptera (lace winged flies and ant lions), Orthoptera (pray ing mantis and cockroaches), Odonata (dragon-.
flies), Diptera (robber-flies and tachina-flies), Coleoptera (lady-bird beetles and tiger beetles) and Hymenoptera (ichneumon flies and spider wasps). In group four are many species of scavenger beetles and flies the larva, and in many cases also the adults, of which mimic the role of turkey buzzards, vultures and other creatures that feed on carrion. In group five are the larva of many beetles (June bugs) and moths (cutworms) which live in the soil.
While these directly or indirectly useful in sects include some of the greatest benefactors of the human race, they number at most only a few hundred species, while those that play harmful roles may be numbered by the tens of thousands. The great majority of these, the most destructive and often the most spectacular in their performance, are those that destroy cultivated crops. Martatt in the Year Book of the United States Department of Agriculture (1904, page 461) declares that the losses caused by insects in the United States alone nearly equal the then running expenses of the national government and were more than the annual cost of the schools of this country. Accord ing to Sanderson, who in his book, 'Insect Pests of Farm, Garden and Orchard,' goes into detail, the annual damage done by insects to cereals is $300,000,000; to animal products an equal amount; to products in storage $200, 000,000; to forests and their products, $100,000, 000; to cotton, $85,000,000; to hay and forage, %6500,000; to truck crops, $60,000,000; to fruits, $30,000,000; to farm forests, $11,000, 000; to tobacco and miscellaneous crops, each $10,000,000; to sugars, $9,500,000, an annual total of $1,182,000,009. Other estimates differ widely from these figures. For instance, Quaint ance places the annual loss to deciduous fruit interests at more than $66,000,000. Texas loses annually $25,000,000 through the Mexican cot ton boll weevil, an insect which has been spread ing to other parts of the cotton belt and whichi it is figured, will sooner or later cost this area at least 10 times this amount annually. Webster totals the losses of cereals for 15 ears due to the work of chinch bug at $350, 000. Herrick says that the codling moth w se larva make wormy apples and pears destroys more than $12,000,000 worth of fruit a year.