1922 ENTOMOLOGICAL SOCIETY. 2d 



THE IMPORTED ONION MAGGOT IN BRITISH COLUMBIA WITH 

 NOTES ON ITS LIFE HISTORY AND CONTROL UNDER "DRY BELT"' 



CONDITIONS. 



R. C. Treherne, Dominion Entomologist in charge for B.C.. and 

 M. H. Ruhmann, Assistant Provincial Entomologist. 



The imported Onion Maggot, Hylemyia antiqaa, (Meigen), is known to have 

 been present in British Columbia for many years. William Couper, writing in the 

 1S75 Report of the Ontario Entomological Society, states that this species "is 

 a terrible pest throughout the extent of the Dominion." Inasmuch as this date 

 was ten years before railway connections were (made with the Prairies and only 

 five years after British Columbia entered Confederation, the record is of interest. 

 Dr. James Fletcher in 'his first Annual Report as Dominion Entomologist in 1884 

 records the Onion Maggot as having been very injurious in many districts in 

 Canada. His correspondent, Mr. Homer of New Westminster, in this year, how- 

 ever, makes no mention of the Onion Maggot in British Columbia. In the second 

 Annual Report for 1885 the Onion Maggot is dealt with in detail and particular 

 attention is drawn to the serious attacks of this insect in Ontario and Quebec, 

 but no reference is made to British Columbia. In view of the lack of published 

 data, it is possible that this insect did not occur in British 'Columbia at this 

 early date. This belief is (based on the lack of references to British Columbia in 

 Dr. Fletcher's Annual Eteports 'between the years 1885 and 1903. In the 1904 

 report, however, we find the first direct suggestion that this insect occurred in 

 British Columbia. It was not until the year ending 1909 that direct proof that 

 this insect occurred in British Columbia was received, according to these same 

 reports. 



During the past ten years reports of injuries caused iby this insect have heen 

 common in the humid transitional areas of the Pacific Coastal region, but they 

 have been confined usually to garden and small vegetable plantations. In the 

 arid transitional areas or in the so-called "dry belt" of the province, onion growing 

 on a commercial basis has been in vogue for ahout eight years, but the first 

 specimens bred to maturity were obtained in 1912. In 1914 this insect had 

 become very injurious and extremely numerous especially in the north end of 

 the Okanagan Valley. The acreage in onions during the past few years comprises 

 between 500 and 800 acres at the two settlements of Vernon and Kelowna. 

 During 1914 and 1915 some growers were literally forced to abandon commercial 

 onion growing and to-day are undecided as to the value of the crop with this 

 insect prevalent in the country. 



In the year 1917, in the Okanagan Valley of British Columbia, the demand 

 for information as to the control of this insect became so insistent that the senior 

 author decided that some action was necessary. Consequently in the year 1918, re- 

 view of the literature on this insect under North American conditions was under- 

 taken. A surprising lack of detailed information both as regards the life-history 

 and the control was revealed. The sodium arsenite and molasses bait as a remedial 

 measure was receiving prominence at the time and while several authors were 

 subjecting this method of control to certain criticisms, the method seemed to 

 possess the weight of authority behind it. 



We were unable to conduct any material investigations in 1918, owing to the 

 pressure of other duties, but we felt justified in advising our growers to apply the 

 sodium arsenite bait using the open "pie 'dish" method of application, believing 



