B. C. ENTOMOLOGICAL PROCEEDINGS, 1912. 81 



PRELIMINARY NOTE ON THE FINDING OF HYPODER- 



MA BOVIS' AT AGASSIZ, B. C, TOGETHER WITH 



NOTES ON THE BIOLOGY OF THE FLY. 



By Seymour Hadwen, D. V. SCI. 



Experimental Farm, Agassiz, B. C. 



The species of Warble-fly recorded here for the first time in Can- 

 ada, and probably for North America, is Hypodcrma bovis (DeGeer). 



Up to the present time, Hypoderma lineata has been considered to 

 be the Warble-fly of North America. During the past summer (1912) 

 six specimens of H. bovis were captured attacking cattle, and seven flies 

 were bred from pupae. The average time taken for the emergence of 

 flies from the pupa was 34.7 days. 



Experiments on Oviposition. 



Experiments were made with flies which had tlieir wings clipped, 

 but, though eggs were extruded, the usual mode of oviposition was not 

 ascertained. On tying cattle up securely, and allowing flies to oviposit 

 on them, it was found that the eggs are laid on the legs, and that none 

 were discovered above the stifle on the hind legs, or above the elbow 

 on the fore limbs. It was proved that the eggs are attached to the 

 base of the hairs, and that they are laid singly. The egg comes out 

 of the ovipositer with the grooved end first, the groove being fitted on 

 to a hair, and adhering to it with a gummy substance. Eggs laid by 

 flies in captivity (in vials) were not found to be sticky, so that the 

 assumption is that the gummy substance is enclosed within the groove. 

 Egg-laying was witnessed a number of times, and the conclusion was 

 reached that the terror which inspires cattle to stampede, or "gad," is 

 caused by the persistent attack of the insect. When Tabanidae, for 

 instance, annoy a cow, she flicks them ofif with her tongue or tail, and 

 they leave for a moment, but Warble-flies seem indifferent to the kicks 

 or stamps of an animal, and when cattle lose their heads and run, the 

 fly still follows, inspiring them with terror, and the result is a stam- 

 pede. 



That the fear of Warble-flies is contagious among cattle, was 

 proved by the fact that stabled animals, seeing others stampeding through 

 the windows, endeavored to break away. 



Larvae. 



Lar\'ae under 5mm. in length were secured from the gullets of 

 cattle as early as August 15th. All the full grown larvae collected at 



