52 



of the offspring of adult flies belonging to each species ovipositing on 

 plants known of a certainty to be free from infestation })y other 

 species. Such studies can only be carried out with the aid of better 

 conveniences than 1 have had at my disposal, and should be taken up 

 by the General Government, whose investigators are not restricted by 

 State lines, and who can follow wherever their problems may lead them. 

 Though Osc/fu's soror {O. varkihilis) has been reared from growing 

 wheat by others as well as myself, I have found that O. carhonaria 

 has been thus obtained with the greatest frequency over the widest 

 range and under conditions that lead to the belief that it is the more 

 important of the two, from an economic point of view at least. 



LIFE HISTORY. 



This can only be given in a general way, as in no instance has the 

 progeny of a single female been carried through the life cycle and the 

 several broods throughout the year clearly defined. I have myself 



reared this species from 

 growing wheat in Illinois, 

 Indiana, and Ohio, over not 

 to exceed two degrees of lat- 

 itude, or collected them in 

 lie wheat fields throughout 

 this area, or they have been 

 reared in Washington in the 

 Department insectary from 



Fig. 15.— Oscmw soror Macq.; «, mature fly: h, antenna plants SCnt there by me f rom 

 of same: c, puparium: r«, head of O. cor5(mana—«, c, rf, \\[^\^ same territory, aS fol- 

 magnified; />, still more enlarged (original). tt u ril I i 



lows: Urbana, 111., 'luly, 

 August, and September; Oxford, Ind., from May to October, not inclu- 

 sive; Lafayette, Ind., July, August, and September; Wooster, Ohio, 

 May, June, July, August, and September; and in the latter locality 

 from August-sown wheat. In the insectary I have also reared it in 

 November, December, and the following April, but did not observe it 

 abroad in that locality during November, December, or April. Besides 

 these rearings of mine, it was reared at Washington, July 7, from plants 

 received on the 3d of same month from Prof. Lawrence Bruner, 

 West Point, Nebr., and reared by Forbes, in Illinois, September 17, 

 from volunteer wheat. This is the species mentioned by Doctor 

 Fletcher as being so destructive in the Dominion of Canada in 1890, as 

 shown by specimens of the adult which he has kindly sent me. « 



There was a bad outbreak of this insect in a field of wheat near 

 Wooster, Ohio, in the fall of 1891, and the field was badly affected. 

 In March of the following year I found many larvae and pupae about 

 the bases of the affected plants, and an attempt was made to study 



a See Experimental Farm Reports, 1890, p. 158, and 1898, p. 177. 



