INJURING CATTLE. 265 



blood is then sucked into the stomach of the fh\ 

 Cows thus attacked become restless and irritable, and, 

 if the flies are very numerous, they lose flesh and 

 give less milk. 



The eggs of the Horn Fly are deposited in freshly 

 dropped cow-dung in which the larvae develop, and 

 pupate in the soil beneath. There are four or five 

 broods each season. During hot weather the trans- 

 formations of the insect — from egg to imago — may 

 be completed within two weeks. 



Remedies. — Two classes of preventives may be 

 used against this insect. The injuries to cattle may 

 be prevented by applying to their bodies, by means 

 of a sponge, fish oil to which has been added a little 

 carbolic acid. Only the tips of the hairs need be 

 wet, and the application should be repeated every 

 four or five days. This will keep the flies off the 

 animals, though it does not kill them. They may 

 be killed, however, by the use of tobacco powder, 

 dusted on the cattle, especially on the back, tail, neck, 

 and base of the horns. Professor J. B. Smith recom- 

 mends the use of the carbolated fish oil on the belly, 

 udder, and other parts of the body where the tobacco 

 cannot well be applied, and the application of the 

 powder to the other parts. The larvae also may be 

 destroyed by spreading out the cow droppings each 

 morning, so that they will dry up, and thus prevent 

 the development of the eggs or maggots, or by mix- 

 ing plaster with the manure in the stable or field. 



