AGRICULTURAL AND MISCELLANEOUS NOTES. 



Sheep Gad-Fly, or Nostril Fly. 



The Sheep Gad-fly, Oestrus ovis, is in appearance not unlike 

 an overgrown house fly. It is very quick in its movements, and 

 difficult to catch. When examined with the naked eye the 

 upper part of the head and thorax appear brown, but when a 

 magnifying glass is used the colour is found to be a dull yellow 

 dotted over with little black elevated spots. The abdomen con- 

 sists of five rings of a variegated dark brown and straw colour ; 

 the feet are brown. The eyes are purplish brown and three 

 small eyelets are distinctly visible on the top of the head. There 

 is no mouth. The wings are transparent, and extend beyond the 

 body, and the winglets, which are quite large and white, entirely 

 cover them. The wings, however, are seldom used except when 

 the fly is attempting to deposit its young. The males are not 

 unlike the females, but are somewhat smaller, and do not disturb 

 the sheep. 



The fly works during the heat of the day, buzzing around the 

 sheep, and trying to get a lodgment at the entrance to the 

 nostrils in order to deposit its young. During this process the 

 sheep are noticed to shake their heads and stamp the ground, at 

 the same time keeping their noses close to the earth, and 

 frequently running along in this peculiar position. At other 

 times they stand huddled together in the shadow of a building 

 or hedge with their heads in close contact to the ground or their 

 neighbour's body. 



If the fly, however, finds lodgment, it immediately deposits its 

 young in the form of small larvae or grubs. These larva: are 

 about one-twelfth of an inch in length, and when examined with 

 a lens are seen to consist of a body divided into eleven segments 

 two well-defined hooks, and two minute terminal breathing pores. 

 Their ventral surfaces show numerous little spines which later on 



