214 DIPTEEA OE TEUE FLIES. 



(Gomurus cerebralis) by the copious mucous discharge from the 

 nostrils, and the absence of that rotatory movement seen in 

 sheep suffering from Sturdy. 



Prevention and Treatment consist in warding off the ily 

 attack by either placing some substance on the sheep's nose 

 every now and then, such as strong smelling oils, removing 

 them for a year from pastures that are known to be contaminated 

 with the puparia, and placing salt in tarred boxes, so that the 

 sheep get the creosote on their noses whilst licking the salt. 



The Horse-bot (Gastrophilus equi). 



The Horse-bot Fly (fig. 106) is brownish-grey in colour, has 

 mottled brown wings, and appears much about the same time 

 as the other two just mentioned. The eggs (a) are quite large 

 objects, laid on the hair of the horse at the knees and shoulders. 

 It seems that at the same time as the female lays her eggs .she 



places some irritating poison on 

 the skin, which causes the horse 

 to lick the spot. The warm 

 breath hatches the larva, which 

 attaches itself to the tongue and 

 crawls down the animal's throat, 

 taking up its position in the left 

 Fig. io(i.— HoESE-BOT Fi.Y(Gas(ro- or cardiac portion of the stomach 



p/»Z«eg«) (slightly enlarged). (the white half). Thebotscon- 



A, Ova. enlarged. ^ ' 



gregate here, and hold on to the 

 mucous membrane by their two-hooked mandibles until mature. 

 They are pinkish - white barrel • shaped larvae, with circles of 

 spines (fig. 107, a). We see them sometimes sticking round 

 the horse's anus. At least six months is passed in the horse's 

 stomach ; 'when maturity is reached they pass out via the in- 

 testines to the exterior in the faeces, pupating in a puparium 

 case on the ground, like H. hovis and CE. ovis. 



Prevention and Treatment. — Well-groomed horses seldom 



