5 



PRACTICAL ZOOLOGY 



of rows of booklets to the lining of the stomach (Fig. 29). As a 

 result of the presence of several hundred " bots," the horse suffers 

 because of interference with its digestion, and from the irritation 

 caused by the insects. When full-grown, the larvae pass out of 

 the alimentary canal with the excretions and pupate in the 

 ground. The eggs are plainly visible when attached to the hairs 

 of the animal; the hair should be shaved off or moistened 



with kerosene, which 

 kills the eggs. 



The sheep botfly 

 resembles the horse 

 botfly in general ap- 

 pearance but differs 

 from it in its habits. 

 The eggs of the sheep 

 botfly hatch within 

 the body of the fly 

 and the living young 

 are deposited during 

 June and July in the 

 upper nasal passages 

 of the sheep, where 

 they feed upon 

 mucus. They are 

 provided with short, 

 stiff spines which 

 enable them to move forward, and with mouth hooks by 

 means of which they can attach themselves to any place se- 

 lected. Sometimes these disgusting larvae even make their 

 way through the skull and into the brain, causing " staggers," 

 a disease that results in death. A mixture of tar and grease 

 smeared on the sheep's nose is partially successful in warding 

 off the attacks of these flies. When the sheep actually become 

 parasitized, the bots may be dislodged by causing the animals 

 to sneeze them out, the sneezing being induced with powdered 



FIG. 30. Ox botfly or heel fly : A, adult ; B, 

 eggs attached to hair ; C, larva or grub ; D, grub 

 just beneath air-hole in skin of an ox. (After 

 Ransom.) 



