February "21] gossard and parks: hessian fly prevention . 59 



A considerable number, which had not emerged, contained Hessian-fly 

 larvae which apparently would not emerge until spring. The word was 

 given to Williams and surrounding counties to sow wheat after the 27th. 

 For Erie and surrounding counties, October ist was the date selected. 

 On September 28th, many drills were starting in the north-western 

 coimties, though some chose to wait a little longer. 



The result of the extension effort was indeed gratifying, and the 

 response almost unanimous. Less than one percent, of the wheat had 

 been sowed before the final dates chosen. In many townships not an 

 early sowed field could be found. Seeding proceeded promptly during 

 the first ten days of October. At no point were many Hessian-fly eggs 

 found from September 30th until October 14th. The young wheat had 

 escaped a very heavy infestation and was looking well. The little 

 early-sowed wheat that could be found, in most counties, had become 

 heavily infested with the fall brood soon after it came up. 



October Egg-laying 



An unexpected appearance of adult flies during mid-October over all 

 except north-eastern Ohio, resulted in many eggs being deposited 

 between October 14th and 19th. This emergence was over by October 

 20th. Wheat which came up too late to become infested by the main 

 fall brood, then became infested with eggs, and later with the maggots 

 of the fly. At Coliunbus 802 eggs were deposited upon 100 plants 

 kept under observation during that time. 



Proof was obtained that this late wave of emerging adults came from 

 flaxseeds which developed during June on the main crop. Hence 

 the\- did not represent a true supplementary^ brood, but came from "hold- 

 over" flaxseeds which did not give up their occupants during September 

 as previously observed. This "holdover" stock of summer flaxseeds 

 was exceedingly large, and only a part of them gave up adult flies during 

 October. The remainder are carrying their occupants, doubtless to 

 enhance the numbers of the spring brood. Instead of emerging in 

 September, the fall broof of 1920 divided into three parts as follows: 

 1 — September emergence of the normal fall brood. 2 — Mid October 

 emergence or "late wave." 3 — "Carry over" flaxseeds still unemerged 

 in midwinter. 



The maggots which hatched from the eggs deposited by the late 

 wave adults grew quite slowly, and caused some damage to all wheat 

 above ground before October 16th. About 20 percent, of these plants 

 became infested. 



Thus, by an eleventh hour effort, the Hessian-fly prevented what 

 looked to be a complete and statewide control as the result of the united 



