April, '17] PARKS: HESSIAN FLY SURVEY 251 



Kansas State Experiment Station, to whom acknowledgments are 

 here due. 



The accompanying data, including the tables and graphic compari- 

 sons, were prepared to show the effect of time of sowing and the pres- 

 ence of volunteer wheat upon the degree of injury by the Hessian fly 

 in this county in 1916. 



A comparison of Tables I and II shows the effect of the time of sow- 

 ing upon the control secured. The good of late sowing is here more 

 clearly observed than the evil of early sowing. It is left for the reader 

 to explain why 23 per cent of the fields sowed before the fly-free date 

 escaped with slight injury, though these fields must have been heavily 

 infested in the fall and probably were the source of a large part of the 

 spring brood which damaged the wheat throughout the whole county. 

 Table II shows the value of late sowing when the seed-bed is free from 

 volunteer wheat. The five fields that were seriously injured were all 

 near and usually adjoining early sowed fields. In one case a four-acre 

 strip was sowed early and on both the north and south of tliis the adjoin- 

 ing fields of wheat, which were classed in Table II, were found to be 

 very severely injured by fly. The north field was the more severely 

 injured of the two, presumably because of the prevailing winds from 

 the south during the spring. The early sown strip was too severely 

 injured to harvest. The protection afforded the wheat in Table II 

 shows the importance of even an unorganized attempt to control the 

 Hessian fly by sowing after the fly-free date. In this class it was ob- 

 served that the extent of the damage usually depended upon the ability 

 of the plants to overcome the attack of the fly larvae. Usually but a 

 few were observed on each plant, and in good soil and on seed-bed well 

 prepared, these straws were able to mature a head and remain standing 

 even though one flaxseed was present near the base. 



The effect of the presence of volunteer wheat in the seed-bed was 

 even more noticeable than was expected. The grower's word was ac- 

 cepted for the amount of volunteer wheat present in his seed-bed. 

 This could usually be verified by inspection. It was thought best to 

 make but three divisions in regard to the amount of volunteer wheat 

 present. A comparison of Tables II, III and IV shows the effect of 

 varying amounts of volunteer wheat upon the subsequent injury by 

 the spring brood of flies to the main crop of wheat sowed after the fly- 

 free date. The heavily infested fields in Table IV were often in worse 

 condition than those in Table I where no attention was given to time 

 of sowing. Wheat shown in Table IV was probably subjected to 

 equally as severe an attack by the spring brood of flies as that in Table 

 I, but had the disadvantage of being younger and with fewer tillers. 

 The figures in the last three tables show clearly that the degree of in- 



