374 Diseases of Sheep, 



SHEEP BOTS— GRUBS IN THE HEAD— HEAD MAGGOTS. 



We have described on an earlier page (p. 150), the his- 

 tory of the gadfly or bot fly in the horse. The species of the 

 same insect which attacks the sheep, the oestrus ovis, does not 

 choose the stomach or bowels as the place of its residence 

 when in the larval condition, but a far more annoying part 

 of the body of its unwilling host, to wit, the nostrils and 

 frontal sinuses, or hollow chambers in the front of the skull 

 communicating with the nostrils. 



The sheep greatly dread the fly, and at its approach will run 

 wildly about, bury their nostrils in the dust, or gather together 

 in groups, with their heads downward, jostling against each 

 other, to drive away their enemy. When struck by the fly 

 they stamp the ground violently, and exhibit other signs 

 of distress, amounting to agony. 



As soon as the larva is deposited at the entrance of the 

 nostril, it proceeds upward, holding on by the firm hooks 

 which arm its head, and makes its way into the furthest 

 recesses of the nasal chambers, causing the animal, in its 

 progress, great pain and irritation, resulting sometimes 

 in vertigo, inflammation of the brain, madness and death. 

 When the disease has reached its highest point the animal 

 loses flesh, falls down frequently, grinds its teeth, rolls its 

 reddened eyes, and finally dies on the fourth or eighth day. 

 In mild cases recovery takes place unaided ; the larvae are 

 thrown out by frequent sneezing, along wdth mucus ; and 

 this is the only sure sign of the disease, at least, for the non- 

 professional. Sometimes vertigo is present at the same 

 time. 



If the head of a dead animal is opened, more or less 

 larvae are found in the above-mentioned cavities, which re- 

 semble those found in the stomachs of horses. The mucous 

 membrane of these cavities is inflamed, red, bluish, dark- 



