PARASITOLOGY. 29 



Life Cycle. — The fly is viviparous, and attacks the 

 sheep and goats from June to October, but only in 

 the warmer part of the day. It deposits its larvae 

 in the anterior nares. The larva is provided with 

 two booklets, by means of which it gradually works 

 its way to the frontal sinuses, where it passes the 

 larval stage, which requires ten months. It then 

 passes out to the ground, burrows into the ground 

 and there passes through the pupal stage, which lasts 

 from four to six weeks. 



Animals' Attacked. — Sheep and goats. 



Parts Infested. — Frontal sinuses and turbinated 

 bones of the head. 



Condition Produced. — The sheep, hearing the noise 

 of the fly, runs, thrusts its nose into the ground or 

 amongst other sheep, and strikes at its nose wnth its 

 feet in an effort to rid itself of the pest, which, slug- 

 gish at other times, now flies at the nostrils with 

 great rapidity. The larvae work their way to the 

 frontal sinuses by means of booklets and contractility 

 of the body. In the frontal sinuses they attach 

 themselves, by means of two booklets, to the mucous 

 membrane. If only three or four are present in 

 the sinuses they do not produce much disturbance, — 

 a slight catarrhal discharge of a muco-purulent na- 

 ture. When many are present there is noted a pro- 

 fuse muco-purulent discharge from the nostrils, loss 

 of appetite, frequent coughing and sneezing, slow, 

 weak gait, and tossing of the head. The animal 

 becomes too weak to rise, and finally dies. 



Treatmejit. — Trephine and remove larvae with for- 

 ceps. 



Prophylactic Treatment. — The nose may be smeared 



