25 



My first visit to this field was made August 4, at which time 

 two strips had been sowed, the wheat on the first being four 

 inches high a ad that on the second just coming up. Several hours' 

 search in the former plot gave no trace of the fly in any condition. 

 A large number of plants sent to the office were carefully scruti- 

 nized, especially for the egg upon the leaf, but likewise without 

 success. This wheat was badly damaged (as already said) by the 

 third brood of the wheat bulb worm {Meromyza cmMcana), one 

 half to two thirds of the plants having been already killed by this 

 insect. On the ^Oth August these plots were visited by my assist- 

 ant, Prof. Garman, and the volunteer wheat mentioned above was 

 also searched, but equally without result. The wheat was now al- 

 most exterminated by the bulb worm upon the first two plots, and 

 these were thereafter left out of the account. Only small patches 

 occurred where the plants w^ere possibly thick enough to attract 

 the imago. 



On the 4th September I spent several hours in the volunieer 

 ivheai (which, it will be remembered, sprang up about the 20th 

 July), searching in every imaginable way for eggs and larvae, but 

 finding nothing of the Hessian fly. Three hundred and seventeen 

 plants selected from those least flourishing were sent to the oflice 

 and there carefully searched, magnifier in hand, for both eggs and 

 larvae, but not one of either was detected. 



Again, September 18, this field was thoroughly investigated, 

 about two hours being spent by myself and several volunteer assist- 

 ants in closely examining leaves and stalks and tearing the plants 

 in pieces. Although several other dipterous larvae and pupae were \ 

 discovered, some of them possibly injurious to the plant, not a V 

 trace of the Hessian fly was seen. The owner assured me, how- 

 ever, that he had the day before happened upon two puparia 

 which he was certain were those of the species in question. Ten 

 days later ( on the 28th Sept. ) I received from Mr. Young a small 

 vial of alcohol, containing larvae and puparia of the Hessian fly, 

 the latter freshly formed, the former from half to full grown. 

 These were taken by Mr. Young from the volunteer wheat, and 

 were the earliest positive indications found that this wheat had 

 been infested. As about three weeks* is required for the growth 

 of the larva from the egg, the latter was probably laid for the 

 larger larvae not long after September 5. 



The difliculty of finding in fields of wheat a feAV scattered ex- 

 amples of objects so minute as the egg of the Hessian fly, explains 

 our failure to detect it at the time. Indeed it was not until the 

 individual plants began evidently to suffer that it became at all 

 easy to find even larvae in the field. 



October 11, I again visited Billett Station, and found numbers- 

 of larvae and puparia of the fly, about one third to one half of ther 

 stalks being infested, and those containing the pupuria all dead. 

 Probably a tenth of the specimens obtained were puparia, seven 



• See next page. 



