324 INSECTS ATTACKING STOCK AND POULTRY 



there pass the pupal stage. There are several generations during 

 the year. 



Control. Tar and fish oil in equal parts may be applied as a 

 repellent upon the flanks of cows; or a mixture of half a cup of 

 kerosene in a quart of rancid lard may be used in the same way. 

 The latter repellent is ordinarily effective for two or three days. 

 When numbers of cows are to be treated, spraying with fish oil 

 should be resorted to. As is well known, cows kept in the stable 

 during the day and turned into pasture at night are exempt from 

 attacks of all insects that fly during the daytime. 



The Stable Fly (Stomoxys calcitrans Linn.). This fly also 

 closely resembles the house-fly. Very abundant about stables in 

 the late summer and early autumn, it sometimes enters dwelling 

 houses in muggy weather. Sharp, piercing mouth-parts distin- 

 guish it from the house-fly. Its 

 habits are very much the same 

 as those of the latter. 



Life History. The eggs are 

 laid in moist, decaying sub- 

 stances and hatch in from one 

 to three days. The pupal stage 

 lasts from six to twenty days, 

 depending upon temperature. 

 Unlike the house-fly, it does 

 not, by choice, breed in manure, 



FIG. 328.-Horn flies on horn of cow. but pre f ers wet gtraw stac ks Or 



manure containing plenty of straw. It is found to be more abun- 

 dant in old oat straw than in wheat straw, and breeds in numbers 

 in debris left from threshing. The complete cycle, from egg to 

 adult, occupies about nineteen days. 



Injury. Like other flies which frequent filth, this one is poten- 

 tially a distributor of disease. It is practically cosmopolitan, but 

 becomes of great importance in the grain belt. It can easily bite 

 through clothes, and frequently bites ankles when low shoes are 

 worn. It is very evident that, since it flies from one animal to 

 another, it may be the cause of spreading anthrax hi both animals 

 and man; also glanders; and possibly swamp fever in horses. It 

 also acts as an intermediate host for a round worm of cattle, as 

 well as for many diseases of animals, in other continents. In 

 Texas the loss from the attacks of this fly is estimated at over 

 twenty-five thousand dollars. 



