BRITISH COLUMBIA ENTOMOLOGICAL 

 SOCIETY. 



PROCEEDINGS, 1920. 



THE ONION-MAGGOT. 



R. C. Treherne, Entomologist in Charge for B.C. Dominion 

 Department of Agriculture, and M. H. Ruhman, 

 Assistant Provincial Entomologist. 



GREAT deal of conflicting evidence is before us on the control 

 of this injurious insect. Even now after one year's concen- 

 trated study of this insect at Vernon in the " Dry Belt," where 

 li li u I it is yearly assuming greater importance, and after two years' 

 V^te/ observations on its general activities and habits in that district, 

 ' I we are unable to claim to have devised a scheme for control 

 which completely satisfies us. Our investigations have led us along defi- 

 nite channels which may result in something definite after a while. 



In glancing over the literature on this insect we find the following sug- 

 gestions for its control : — 



" Liberal amounts of tobacco-dust." (O'Kane.) 



" Clean up and burn refuse after harvest." (Sanborn, Oklahoma.) 



'■ Rotation of crop, destroy infested plants, and apply carbolic-acid 

 enuilsion to soil." (Conradi, South Carolina.) 



" Destroy refuse, wild mustards, and cruciferous weeds ; rotate crops ; 

 fertilizers ; frequent surface cultivation ; tobacco-dust and sulphur in drill- 

 rows with seed; hellebore; and slaked lime as a dust to the soil. (Lovett, 

 Oregon.) 



" Cultural control measures and use of trap-crops with deterrents of 

 sand and kerosene, carbolized lime, charcoal, hellebore, tobacco-dust, and 

 dry lime." (Britton, Connecticut.) 



" Control by repellents and fertilizers ; take up infested bulbs and 

 destroy." (Pettit, Michigan.) 



These suggestions for control are representative of the remedial 

 measures adopted for this fly until about the year 1913. During 1913, 1914, 

 and 1915 the poisoned-bait method for control was devised and used exten- 

 sively in Eastern United States. Eastern Canada has also used this new 

 method with great success. In brief, the recommendation called for the 

 use of 5 grammes of sodium arsenite dissolved in J-4 pint of molasses and 

 water. This mi.xture was applied to the fields of onions as soon as the 

 onions were up in about two applications a week until the latter part of 

 June. It was either whisked out of a bucket across or in the rows of 

 onions or it was sprayed in coarse drops from a hand-sprayer. The object 



