1913.1 PUBLIC DOCUMENT — No. 31. 171 



EXPERIMENTS FOR THE CONTROL OF THE 

 ONION MAGGOT. 



H. T. FERNALD AND A. I. BOURNE. 



Onions are grown on a large scale in many parts of Massa- 

 chusetts, particularly in the Connecticut valley. Fields cover- 

 ing 10, 15 or even 25 acres are common, and the crop is an 

 important one. 



For some years the onion maggot, rjioi'hia cepetorum Meade, 

 has been a serious enemy of the onion grower in this region, 

 much loss having been caused by its ravages. In 1911 this was 

 particularly the case, one individual who had 6 acres planted 

 estimating his loss by the attacks of this insect at about $400. 

 Quite a part of this was on one plot covering only 2 acres, which 

 was so thoroughly infested as to make the crop there hardly 

 worth gathering. It has seemed desirable on this account to 

 investigate methods for the control of the onion maggot, par- 

 ticularly as applied to large fields. 



The Problem. 



1. To determine the effectiveness of various methods for the 

 control of the onion maggot. 



2. To determine whether any which prove effective can be 

 used in large fields without too great cost. 



Previous Experiments. 

 An examination of the literature on this subject showed that 

 most of the work had been primarily with other maggots such as 

 the cabbage maggot, Pegomyia hrassicae Bouche, and that con- 

 clusions had apparently to a large extent been drawn from these 

 experiments. Where this was not the case it seemed probable 



