MANAGEMENT OF DAIRY CATTLE 215 



is typical for the summer season under conditions where the 

 dairy cow is made secondary to other lines of farming. Where 

 dairy farming as a specialty is practiced, such great declines 

 in production do not ordinarily occur, on account of better 

 management. The much smaller decline with the college herd 

 was the result of supplementing the pasture with green feed. 



Flies that trouble Cows. Cattle in this country are 

 troubled mostly by two varieties of flies, known as the stable 

 fly, Stomoxys calcitrans, and the horn fly, Hcematobia serrata. 

 The stable fly resembles the ordinary house fly in appearance; 

 but while the house fly does not bite, the stable fly has mouth 

 parts that enable it to pierce the skin and suck the blood of 

 animals. The eggs are laid mostly in manure, horse manure 

 preferably, but also in cow manure. The period for develop- 

 ment is about fifteen days from egg to adult fly. 



The horn fly was introduced into America about 1886. 

 It is considerably smaller than the house fly, and gets its name 

 from the characteristic of gathering about the base of the 

 horns. It is also recognized by the habit of feeding with 

 the wings spread, and usually goes in swarms. Its bite is 

 very irritating, and causes a congestion resembling the bite of 

 a mosquito. The eggs are laid in fresh manure, and require 

 about ten days to develop adult flies. These flies remain with 

 the cattle constantly, roosting largely on the horns. 



Since the flies that annoy cattle are hatched in manure, the 

 first precaution to be observed in reducing the numbers to the 

 minimum is to avoid an accumulation of manure where it 

 will remain moist, and especially near the barn. Since horse 

 manure seems to be preferred by these pests, special care 

 should be taken not to allow it to remain in heaps near the 

 barn. Where a small amount of manure accumulates, it is 



