April, '16] HASEMAN: HESSIAN FLY 291 



AN INVESTIGATION OF THE SUPPOSED IMMUNITY OF 



SOME VARIETIES OF WHEAT TO THE ATTACK OF 



HESSIAN FLY 



By L. Haseman, Columbia, Mo. 



It is a well-known fact that some varieties of trees and other plants 

 possess a greater or less degree of immunity to certain diseases and 

 insect pests, while other similar varieties or strains are very suscep- 

 tible to them. This is true not onh^ of the plants themselves but also 

 of some fruits and seeds. Among practical farmers and grain breeders 

 there is a general impression that some strains of wheat are less af- 

 fected by smut, rust and Hessian fly. If this is the case, other things 

 being equal, that strain which has tendencies toward immunity would 

 seem to be the one to grow. However, there are many other factors 

 which must be considered. 



The variety of wheat which is most susceptible to fly attack may 

 possibly be more hardy, and more given to stooling and in this way it 

 may perhaps yield more grain than other varieties less severely at- 

 tacked by the fly. In other words one variety may be able to furnish 

 food for a large crop of flies and yet yield more grain than a second less 

 susceptible variety. Since the farmer is after yields, he wants to grow 

 that variety which for his locality, gives the greatest jaeld. The 

 Hessian fly, while a most destructive pest of wheat, can, with proper 

 farm practices, be kept entirely under control. Under such condi- 

 tions the use of resistant strains proves of but little value. However, 

 where less careful systems of farming are in force, great good would 

 come from the development and use of a heavy yielding, resistant 

 strain of wheat. 



For the past few years the Hessian fly has been unusually abundant 

 in the Mississippi Valley and in spite of all that we have been able to 

 do in this state the annual loss from the fly has been severe. This 

 inability to secure the needed cooperation of all farmers in some 

 sections for controlling the fly through practical farm practices has 

 led us to undertake this investigation. If we can find among our stand- 

 ard or new varieties of wheat one or more which will stand up better 

 under fly attack, and give even only a small percentage more yield 

 the work will not have been in vain. 



The investigation has been under way for only one season and 

 comparatively little real valuable data has been gotten. Our plan 

 first of all is to determine whether or not the fly really breeds more 

 abundantly in some varieties than in others. If it does we have at 



