188 ZOOLOGY. 



cattle, and seize the parasites with their beaks. Star- 

 lings, rooks, and wagtails destroy the maggots ready to 

 ■become pupae, as they lie on the ground. Remedies : 

 Washing the back, shoulders, and loins with vinegar 

 extract of walnut leaves during the summer, to keep 

 away the bot flies. In spring : squeezing out the 

 maggots from the warbles, having previously opened 

 them, when necessary, with a penknife. If the warble 

 is " ripe," i.e. if it has opened so far that the black 

 hinder end of the maggot can be seen, the opening 

 may be stopped with fat or cart-grease, by which the 

 larva will be killed where it lies. 



The Sheep Bot Fly ((Estrus ovis), 



two-fifths to three-quarters of an inch long, yellowish 

 grey, almost hairless ; head large, round, reddish ; 

 thorax grey, with small black warts ; abdomen 

 yellowish white ; legs short, bright ; wings of a 

 glassy clearness. The flies are found (in September) 

 on the walls of sheep-folds, and in woods near 

 which sheep graze. On sunny days the female flies 

 round the sheep, in order to deposit her brood upon 

 them. The sheep threatened press their nostrils 

 to the ground, though this is not of much use. 

 The maggots are hatched while still in the body 

 of their mother, and are deposited by her on the 

 margins of the nostrils. These little maggots creep 

 about on the mucous membrane lining the internal 

 cavities of the nose, causing intolerable itching. The 

 sheep try to get rid of the intruders by shaking their 

 heads and rubbing their noses on the ground. The 

 maggots, however, creep further into the nasal cavities, 

 and get into the hollows of the frontal bone and upper 

 jaw, perhaps even into the horns. In these places 

 they feed on the fluid which their presence causes 

 the mucous membrane to give out in large quantities. 

 The maggots remain as such for nine months, during 



