46 



This calendar shows our combined work on the insect, and is all the 

 more valna]>le on account of our having worked entirely independently 

 of each other over territory within the same latitude, and with other 

 conditions in every way similar. It is also a matter of interest that 

 on Februar}^ 27, 1891, I collected all stages of the insect except the 

 eggs in wheat growing on the grounds of the Agricultural College of 

 Texas, at College Station. 



LIFE HISTORY. 



Throughout the region of latitude 40^ N. the insect is three-brooded, 

 although there may be but two in the north and more than three in the 

 far south, though Doctor Fletcher states that about Ottawa, Canada, 

 about latitude 45 '^ N., there are three broods, the adults appearing in 

 the beginning of June, the end of July, and again late in September. 

 My observation in Texas, about latitude 30° 30', does not necessarily 

 indicate additional broods, as there may be, as with the Hessian fly, a 

 prolonged summer resting period, during which the insect is continued 

 in a stage requiring no food and incapable of reproduction, until the 

 vegetation upon which the larvae are dependent for their food supply 

 begins to take on new life, and, as with the Hessian fly, we may find 

 that the very conditions that serve to prevent the starting up of the 

 fresh growth of vegetation, so essential to the life of the young larvae, 

 has also the efi'ect of retarding the emerging of the parent insects. Such 

 problems as these are for National investigation, where imaginary 

 lines and political boundaries do not enter into consideration. Within 

 the wheat belt of the United States, broadly speaking, the life cycle of 

 this insect is as follows: The winter is passed in the larval stage, and 

 the short pupal stage coming in May brings the emerging of the adults 

 at the time when the female is able to place her eggs on the plants 

 where the young, on hatching, will make their way to the tender and 

 succulent stem just above the upper joint. By the time the straw has 

 ripened the larvaj have ceased to require food, and pass through the 

 pupal stage, the adults of this brood appearing in July. Eggs are now 

 deposited in volunteer wheat and grass, and, owing either to the retard- 

 ing effects of meteorological influences or a diversity of food of the larvae 

 or both, perhaps, the emerging of the adults is prolonged throughout 

 a period extending from late August through September until late 

 October. At this period the fall wheat offers a decidedly inviting 

 plant to the female fly on which to place her eggs with a prospect of 

 he)' progeny having an abundant food supply. It is the larva? from 

 eggs deposited during this period that winter over in the plants and 

 give rise to the May-June generation of flies. It is this last brood that 

 is of more especial interest to the farmer, as it is very seldom that the 

 pest does serious injury to grain except in fall and early spring. 



