A CONTRIBUTION TO THE KNOWLEDGE OF BOT-FLIES. 



103 



observed flying beneath the abdomen of the horse, near the ground, as if waiting 

 for a favourable opportunity to push home the offensive. A Saskatchewan corre- 

 spondent of Prof. Lochhead (11) relates how an adult of this species deposited an egg 

 on the back of his hand, attaching it to a hair. He also recounts that on several 

 occasions the flies have " struck " at the underside of the brim of his hat. 



A second correspondent, also hailing from Saskatchewan, remarking on the 

 haemorrhoidal bot-fly, observes how " it flies very swiftly back and forth, poises 

 itself for a moment, as though to judge place and distance and then darting upward, 

 stabs a black egg into the lip or chin of the horse, and retreats as swiftly, only to 



Fig. 9. Leather nose-fringe, extended, 

 for protecting lips of horse against the 

 attacks of Gastrophilus haemorrlioidalis, 

 with central flap and fringe to cover the 

 exposed upper lip. 



return at the next suitable moment. The horse can hear it and awaits the attack 

 with nervous apprehension. On feeling the needle-like thrust, it starts violently 

 and rubs its lips or nose on the grass or against another horse." As we have already 

 pointed out, the idea that the egg is inserted into the lip is a fallacy, and the actual 

 deposition of the egg does not cause the animal any physical pain. 



The adult G. intestinalis does not apparently inspire such terror in the animals 

 as the other two species. In thrusting home its attack, it may be often observed to 

 hang on the wing, both before and after the operation is completed. 



Preventive Measures. 



It is usual for western farmers to shield the lips of their horses from the haemor- 

 rhoidal bot-fly by means of a wire-screen muzzle of fairly close mesh. Whilst quite 

 effective for the purpose, it is rather clumsy, besides being an impediment to natural 

 and free respiration. In order to obviate this difficulty, a device such as is represented 

 in figures 9 and 10 might be contrived. The principle consists in nonplussing the 

 attack of the fly by disturbing effects produced by hanging leather strips protecting 

 the nose and lips and agitated into motion whenever the animal moves its head. 



The apparatus, as devised by the authors with the aid of Mr. C. Warburton Young, 

 is quite simple, consisting of a leather-band cut into a series of strips, each about 



