324 WESTERN GRAZING GROUNDS AND FOREST RANGES 



The supposition is that the heel flies sting animals 

 on the heels or hind legs. They also trouble horses but 

 seem to attack them only in front, and a horse will strike 

 out vigorously with his front feet and go almost crazy 

 over a single fly. Time after time have men placed their 

 hands where the heel flies could strike them, but I never 

 knew anyone to be stung or feel the least pain or prick- 

 ing from the touch. 



The heel fly is known to fame as the fly that brings 

 the great "warble grub" in the backs of cattle. There 

 are many skeptics as to the warble part. The activities 

 of the heel or bot fly are confined to depositing its little 

 yellow eggs on animals. These one can easily find, as 

 they are deposited on the hairs of the shoulder or neck 

 and chest just back of the shoulder, low down on the 

 ribs. From there they are taken into the animal's mouth, 

 as it licks itself. It would seem that the instinct of the 

 insect led it to lay the eggs in those places which can be 

 most easily reached by the animal's tongue. 



Once in the animal's body, the egg hatches out, and 

 the grub works its way through the flesh and finally 

 locates under the hide and between it and the flesh on 

 the back, generally forward of and between the hip 

 bones and shoulder blades. There it rests, growing 

 rapdily, finally forcing a little hole through the hide, out 

 of which it eventually passes and drops to the ground. 

 The grubs can readily be discovered by feeling over the 

 animal's back for the lumps which they form. With a 

 little pressure on either side of a lump the grub will pop 

 out of its resting-place through the little hole, doubtless 

 very much to their host's relief. By means of an ordi- 

 nary oil can, such as is used by mechanics, a little tur- 

 pentine or coaloil squirted into the hole will also destroy 

 the grub. 



