386 ANNUAL REPORT OF THE Off. Doc. 



SOME COMMON INSKCT PKSTS OF THE FAR- 

 MER. 



ByU. T. FERXAl.n, Pn.l)., T)fpartm<tit of Entoiiu/ldgij. Massachusetts AgrlcuUiiral College, Amherst, 



Massadiusetts. 



The loss to crops caused by the attacks of insect pests is rarely ap- 

 preciated. A quarter of a century ago even those who studied the 

 subject considered this loss as being about one-tenth of the total 

 crop. To-day this is recognized as being too low and estimates of 

 fifteen, twenty and even twenty-five per cent, are often met with. 

 Whether the earlier estimates were too low, seems doubtful, it being 

 more probable that the actual amount of loss has increased with the 

 increase of continuous acreage taken by man; by the introduction of 

 over seventy-five of the worst pests of foreign countries; and by the 

 decrease in number of our insectivorous birds. To-day every acre 

 tilled, every fruit tree, every vine and every stalk of grass contributes 

 of its substance for the sustenance of insects, and it is probable that 

 before many years pass, every crop must be so treated as to prevent 

 loss by their ravages, if any profit whatever is to be obtained. 



Some of the most frequent and seriously injurious insects with 

 which farmers in Pennsylvania meet are considered in this paper, 

 and, in order to combat these insects intelligently, a knowledge of 

 their lives is necessary; hence a brief outline of the life history is 

 given in each case, in addition to the methods of treatment most 

 generally found to be successful. 



THE HESSIAN FLY. 



(Cecidomyia destructor Say.) 



The Hessian Fly is an insect which causes great loss to the wheat 

 crop in Pennsylvania as well as in all the wheat raising States. This 

 loss varies in amount from year to year; but is always considerable 

 and may be as much as three-quarters of the entire crop. 



