SHEEP S NOSTRIL FLY. 



75 



tion, of which one is — noting that Warble Flies are 

 wost active in heat and sunsliine, and appear not to 

 inirsue cattle over ivatcr ; consequently, allowing the 

 cattle the power of sheltering themselves, and access 

 to shallow pools, is desirable. Likewise with regard 

 to pastures, or standing-ground of infested cattle, it is 

 matter of course that where the maggots have fallen 

 from their hacks the Flies will shortly appear to start 

 neiv attacks. 



\ <*?. if^/S-'.-^-js. 



Fig. 60. — Sheep's Nostril Fly: Fly, magnified (with line showing 

 ratural length), and maggots. Also mouth-hooks of maggot, and tail 

 segment showing spiracles, magnified (after Brauer). 



The attack of the Sheep Bot Fly (the Q^strns [Cepha- 

 lemyia] Oris) is a very serious matter, w4iich causes 

 much suffering to the animals, and loss to their 

 owners. This Fly is rather larger than the common 

 house Fly, and of an ashy colour, spotted with black 

 between the wings, the abdomen spotted with black 

 and silvery or yellowish white. The female either 

 lays her eggs, or deposits living maggots on the mar- 

 gins of the nostrils of the sheep, from whence the 

 maggots crawl up the nostrils by means of the mouth- 

 hooks with which they are furnished, and attach 

 themselves to the membranes of the cavities. Here 

 they feed on the mucus ; and it is stated that they at 

 times feed on the membrane itself. Their presence 

 causes great irritation ; and where the attack is severe 

 leads to gradual loss of strength, and convulsions (and 

 other symptoms by which the cause of the illness is 

 distinguishable, which we need not enter on now), and 



