INSECTS AND ENTOMOLOGISTS 



221 



injury that they cause. There are several native forms, large and 

 small, red and black, that are frequently pestiferous, and within the 

 few years last past we have acquired another, the " Argentine Ant," 

 which, as is customary with introduced pests, does more harm within 

 its present range than all the native kinds combined. 



Again we have reached the Diptera or. flies; but this time there is 

 very little fault to find, for those species, other than the pests already 

 mentioned, that do come into our houses, do so mostly as scavengers. 



And there is yet another heading under which we have to consider 

 insects in their effect upon man, and that is in the light of pests on the 

 crops which are grown by him. A very large percentage of all insects 

 are vegetable feeders and, naturally enough, when large areas are 

 planted to one crop, so as to eliminate for the insect the problem of 

 food supply, and cultural methods lessen their natural enemies, these 

 vegetable feeders flourish out of all proportion to their normal natural 

 limitations. The result is that a considerable percentage of the 

 crop is destroyed, and most of the destroyed percentage represents the 

 farmers' profit. That is to say, suppose it costs $5.00 to cultivate, plant, 

 harvest and thresh an acre of wheat, and the harvest sets for a 15 

 bushel crop. With wheat 

 at $1.00 per bushel at the 

 station, the farmer might 

 count on a profit of $10.00 

 per acre. But if in spring 

 chinch-bug attack reduces 

 the yield by 5 bushels, and 

 the wheat-head army worm 

 destroys 3 bushels more, 

 the net return is reduced to 

 $2.00 per acre, which is not 

 living wage to the owner. 



That this sort of reduc- 

 tion occurs with discour- 

 aging frequenc}*" on many 

 sorts of crops throughout 

 our country, is within the experience of every economic entomologist, 

 and the total calculated loss per annum from insect attack in the 

 United States alone amounts to $1,500,000,000. Surely a terrific tax 

 to pay and one which is not paid without protest. 



Not only is practically every crop attacked, but every portion of the 

 plants may be infested. There are maggots that burrow into the 

 roots of vegetables; borers that live in the roots of trees, shrubs and 

 even meadow plants, and wire-worms and grubs that eat off the rootlets 

 of grasses, strawberries and the like. Potatoes are gnawed under- 



Fig. 13. A root-maggot, a; its pupa, b; and the 

 adult fly, c. 



