74 THE REPORT OF THE No. 36 



and oil of citronella, but this was a complete failure. Since the adult flies have 

 similar feeding habits to the cherry fruit flies, I believe that the same control 

 could be used, i.e., spraying with arsenate of lead. However, this is still to be 

 tested. 



NOTES ON THE SEED POTATO MAGGOT 



(Hylemyia trichodactyla Rond.) 



G. H. Hammond, Entomological Branch, Department of Agriculture, 



Ottawa. 



There are few records of injury by the Seed Potato Maggot from North 

 America, and, so far as can be determined, there are no records of injuries by 

 this insect to turnips. 



The following notes are now presented in reference to this crop as the result 

 of some observations made during the past summer (1922) at Ottawa. 



On August 2nd, a report was received by the Dominion Entomological 

 Branch of severe root injury to turnips in a field near Ottawa. Investigation 

 showed that the tap root of the plants was being cut through about the ground 

 level. The injured surfaces were found to be rather evenly cut, the root being 

 completely separated from the plant in many instances. In all the plants 

 examined there was no evidence of direct tunneling into the turnips. On the 

 date above mentioned the roots were approximately two inches in diameter and 

 the injured seedlings were, in the majority of cases, already shrivelled and dying, 

 and some which survived the initial injury were throwing out a lateral root 

 system. In an acre fully 65 per cent, of the plants were attacked and approx- 

 imately 50 per cent, of the plants were injured beyond hope of recovery. In 

 many cases all of the plants in ten feet of row were destroyed. The injury was 

 not localized, but was distributed generally throughout the field. The owner, 

 Mr. W. F. Bell, stated that the injury had been noted for over a week and that 

 the type of injury was new to him. 



In an examination of the injured roots, puparia were found in the sandy- 

 soil two inches deep and within half-an-inch from the root. These puparia 

 resembled those of the Cabbage Maggot (H. brassicce), but were somewhat 

 smaller. Some larvae were also found feeding in the slight hollows on the upper 

 portions of the main root at the ground level. These larvae, on a superficial 

 examination, resembled the Seed-corn Maggot (Hylemyia cilicrura). 



Adults were reared in due course and they have been identified by Mr. 

 H. C. Huckett, of the Agricultural Experiment Station, Geneva, N.Y., as 

 H. trichodactyla Rond. 



From an article by Johanssen in the Journal of Economic Entomology, 

 Vol. XIV., December, 1921, this insect is recorded in Canada from Truro, N.S., 

 and Sandford, Ont. In the Canadian National Collection of insects there are 

 eleven specimens of Hylemyia trichodactyla, three collected by Mr. W. Metcalfe, 

 at Brockville, dated September 13th and 20th, 1903; seven by the late Dr. James 

 Fletcher, at Ottawa, dated August 25th, 1908, and one from Chateauguay 

 Basin, dated August, 1910, probably collected by J. F. Jack. The specimens 

 collected by Dr. Fletcher were taken off asters, according to information on 

 the pinned specimens; it seems unlikely that they were reared from asters, but 

 were probably taken from these plants in general collecting. 



