RELATION TO OTHER ANIMALS 171 



do not get very far away from the place where they 

 normally breed. 



As a protection against these insects nettings are 

 used on driving horses, and cattle are sometimes pro- 

 tected by smears of carbolated grease or fish oil. The 

 larger horse-flies do not usually attack man, as the 

 green-heads and deer-flies generally do. Where they 

 are abundant enough to cause trouble, the same 

 repellants that serve for black flies will serve against 

 the Tabanids as well, As the ground becomes better 

 drained or cleared, so that breeding places for the larvae 

 are lessened in number, the adults will become gradually 

 less troublesome; and, as a matter of fact, while the in- 

 sects are sometimes horribly annoying, they are usually 

 much fewer than they seem because of their active 

 movements, and it may be quite possible to exterminate 

 some of the species locally, by persistent collecting on 

 some especially favored animal, for a few days after 

 the flies first make their appearance. 



The term "stable flies" is rather an indefinite one, 

 but applies chiefly to one species, Stomoxys calcilrans, 

 of very general distribution, in appearance like a large 

 house fly, but with mouth parts produced so as to be 

 capable of sucking blood. These are often present on 

 horses and cattle in great numbers, and frequently 

 cause great annoyance and distress. They rarely attack 

 humans,- but sometimes in hot, oppressive weather 

 will get at exposed ankles and bite hard, usually with- 

 out causing any noticeable swelling. The larvae are 

 maggots, like those of the common house fly, and de- 

 velop in excrement, preferably in cow dung. If no better 

 lodging is found for them, almost any kind of decaying 

 vegetable matter will be made to answer. 



A near ally to this stable fly is a somewhat smaller 

 species known as the "horn fly" from its habit of 



