202 



SCHOOL ENTOMOLOGY 



horses where these flies are abundant. Various repulsive 

 ointments have been suggested, but are of doubtful value. 

 In sections where the flies are particularly troublesome, the 

 draining of marshy lands may remove their breeding places 

 as well as those of mosquitoes. 



123. The Sheep Tick.* The sheep tick is one of the best- 

 known pests of the sheep. It is not really a tick, but a wing- 

 less fly. It is about one-fourth of an inch long when grown, 



and of a reddish-brown color. 

 The head is small and sunken 

 into the thorax. The middle of the 

 thorax is rather slender and the 

 abdomen is broad. This species 

 is distributed over the world and 

 lives only on sheep. These insects 

 are peculiar in that the eggs hatch 

 and the larvae develop within the 

 body of the female, which gives 

 birth to pupae, from which the 

 adults soon emerge. When the 

 old sheep are sheared the ticks 

 usually migrate to the unsheared 

 lambs. They may cause con- 

 siderable damage to sheep if abundant, which is often indi- 

 cated by the lack of growth and poor condition, and when 

 they mass on lambs their injury is often very serious. 



The only satisfactory method of control is to dip the 

 sheep just before shearing and again in the fall before going 

 into winter quarters. Any of the cresol or creosote dips, 

 lime-and-sulphur, or the tobacco dips, whose labels state 

 that they are approved by the U. S. Department of Agri- 

 culture, may be used as directed by the manufacturer. 

 * Melophagus ovinus Linn. Family Hippoboscidce. See page 139. 



FIG. 144. The sheep tick. 

 (Ky. Agr. Exp. Station.) 

 Greatly enlarged. 



