June, '22] gossard: hessian fly control 221 



THE WESTERN WHEAT STEM SAWFLY IN CANADA 



By Norman Criddle, Treesbank, Man. 



(Withdrawn for publication in the 52d Report of the Entomological 

 Society of Ontario.) 



Mr. R. L. Webster: I have been greatly interested in Mr. Griddle's 

 paper, because this, like other insects, has absolutely no regard for 

 international boundaries. It caused a great deal of damage in North 

 Dakota in 1921. 



I would like to ask Mr. Criddle if it is possible that the same number 

 of insects might be present per square mile over the whole area and yet 

 the damage show entirely in the dry area? 



Mr. Norman Criddle: That is the point I wish to make. The saw- 

 fly is all over the area, but it does not develop where there is a vigorous 

 growth, and that, of course, is brought about by rainfall. 



President Arthur Gibson: The next paper is by H. A. Gossard. 



PROGRESS IN HESSIAN FLY CONTROL 



By H. A. Gossard, Wooster, Ohio 

 (Withdrawn for publication elsewhere) 



Mr. F. Z. Hartzell : I would like to ask the difference between the 

 peak of emergence and the date of plowing? Would it be safe to plow 

 when emergence had been reached, or to wait? 



Mr. H. a. Gossard: That would depend on the density of the 

 brood. In 1920, the brood was so dense that we felt perfectly justi- 

 fied in holding everybody back until the peak was passed and on the 

 decline, because we were siu*e that the tail end of the brood was so 

 heavy that if this method was not followed, we were likely to have 

 very heavy infestation. 



In 1921, the brood was not so heavy and we were not afraid of the 

 tail end of the brood. In other words, the tail end of the brood was 

 not going to be heavier than the normal brood. They laid their eggs 

 a little later than we expected, but we were making observations and 

 did not feel the need for calling for a later seeding. We allowed the 

 farmers to go ahead and seed at the time already agreed upon, and it 

 turned out satisfactorily. If we had had a heavy brood, we would 

 have asked them to wait until the peak was diminishing. 



