an exception, as it has yet to be found attacking the grasses in this 

 country: 3^et several insects whose injuries in the wheat fields have 

 been charged up to it by the farmer ma}^ be destroyed to a greater or 

 less extent b}' closely pasturing the roadsides and fence corners in 

 summer or burning them over in winter or early spring. 



The first group of these grain-attacking insects to which attention 

 will be here given is composed of those that are not flies at all in the 

 true sense of the term, but small ant-like creatures, really related to the 

 ants which they so closely resemble. Their .young live within the stems 

 of the smaller cereal grains and grasses, and, though these rarely kill 

 the wheat stems outright, they may either prevent the production of 

 the kernels or cause these last to shrink and shriv^el, thereby greatly 

 reducing them both in weight and market value. These insects are 

 called the grain and grass Isosomas, and their young are the wheat 

 straw-worms and the joint- worms. What is still more surprising, they 

 belong to a group of insects the majorit}^ of which are not vegetable 

 feeders, but parasitic on other insects, and it was a long time before 

 entomologists were willing to accept the fact that they were the real 

 depredators and not parasites. This doubt as to the real food habits 

 of these insects had not entirely disappeared up to 1884, when the 

 author proved b}' successive rearings not only the vegetal habits of one 

 of the species, but also the even more interesting fact of dimorphism 

 and an alternation of generations, showing that what appeared to be 

 two species was reall}^ two generations of one of them ; but one of the 

 generations, being wingless in the adult stage, renders it the more 

 easily controlled by the farmer through a rotation of crop.'^' 



The second group of insects here considered is composed of true 

 flies, and these also are both grain and grass feeders in the larval or 

 maggot stage. All true flies have but two wings, and the maggots 

 have no jaws, but the mouth parts consist of two minute hooks whereby 

 they tear or slightly wound the surface of the tender stems and suck 

 the juices flowing therefrom. The Hessian fl}" is also a true fl}^ but 

 its form partakes more of that of the mosquito, while these under con- 

 sideration have very much the form of the common house fly, except 

 that they are smaller, and they are frequently quite differenth^ colored. 

 The maggot of the Hessian fly is larger and more robust than are 

 those of the Oscinids, though shorter and difl'ering in color from those 

 of Meromyza, 



Judging from ni}^ own experience and observation, these insects are 

 much more injurious to the young grain plants. One brood of mag- 

 gots of Meromyza work in the full-grown straw it is true, but, as a 

 rule, the injury at that time is seldom very severe, while the larviB of 

 the Oscinids are rarely found in the full-grown straw, except in the 



« Reports U. S. Comm. Agr., 1884, pp. 383-387; 1885, pp. 311-316; 1886, pp. 573-574. 



