34 MORE MINOR HORRORS 



deposits its ova. The eggs of H, bovis are 

 scattered and isolated ; those of H. lineatum 

 are arranged in rows of some seven or more 

 half-way up the hair and are contiguous. 

 The favourite region for placing the eggs is on 

 the hock and on the back of the knee, or on 

 the thighs and flanks, and hence the American 

 cowboys call the insect the ' heel-fly.' Un- 

 doubtedly by standing with their legs in water 

 the herd is delivered from the pest — at any 

 rate, for the time. 



The eggs are large, 1*25 mm. in length, 

 and enclosed in a whitish shell, which is pro- 

 longed behind into a brownish foot, and this 

 foot, which exudes some sticky excretion, 

 adheres to the ruminant's hairs. The foot of 

 the egg-shell, in fact, consists of two lobes or 

 valves, which clasp the hair between their 

 sticky inner surfaces. 



Within the egg the youngest of the four 

 larval stages is maturing. When hatched it is 

 less than 1 mm. long, but it is 'a terror for its 

 size,' being armed with a formidable spine and 

 two hooks in the mouth, and with rows of 

 strong spines on all the body-segments. Later, 

 we find a second stage, very much smoother 

 and less spiny than the first and this lies 

 within the tissues of the host, embedded in its 

 muscles and membranes, notably in the sub- 

 mucous coat of the gullet ; \ and now the 



