3034 



THE JOINTED ANIMALS 



quadruped's mouth. The reason for this, although not at first very obvious, 

 becomes clear when it is understood that the larval fly can only obtain its proper 

 nourishment in the alimentary canal of its host. As soon as the maggot emerges 

 from the egg it starts to irritate the horse's skin. Thereupon the horse, to remove 



the irritation, licks the infested spot and swallows 

 the maggots, which then attach themselves by 

 means of their hook-like mandibles to the inner 

 wall of the stomach or oesophagus, making little 

 excavations, and nourishing themselves by sucking 

 up the secreted mucus. Here in perfect security 

 they live and grow for about a year; after which, 

 when nearly full grown, they enter the intestine 

 and pass out of the body with the excrement. Fall- 

 ing to the ground, the maggots bury themselves in 

 the soil and enter upon the pupal stage. In favor- 

 able weather the perfect insect is produced from the 

 pupa in about six weeks. The ox bot or ox warble 

 {Hypoderma boms} deposits its eggs in the hair of 

 the skin of cattle, and the maggots, after hatching, 

 burrow through the skin and take up their lodging 

 in the tissues beneath, where in course of develop- 

 ment they give rise to the large tumors known 

 as warbles, each of which opens to the exterior by 



DEVELOPMENT OF HORSE BOTFLY. means of a sma11 aperture. In these tumors the 

 a. Adult fly; b. Egg attached to a hair; c. maggots remain for ten or eleven months until prac- 



Mature larva; d Newly-hatched larva; tically f u ll grown> w hen, quitting their host, they 

 e. Pupa. (All enlarged.) 



fall to the ground, bury themselves, and in the 



course of a month or six weeks emerge from the pupa stage as fully-developed flies. 

 The species most commonly met with in England is not H. boms but H. lineatum. 

 It can be easily under- 

 stood from the fact a 5 

 that since no fewer 

 than four hundred 

 maggots, each grow- 

 ing to an inch in 

 length, have been 

 known to infest a 

 single beast, the loss 

 occasioned by the at- 

 tacks of this fly is con- 

 siderable. It has been 

 estimated, indeed, by 

 Stratton, that in the 

 United Kingdom alone 

 a loss of something 



OX WARBI.E FI<Y AND ITS DEVELOPMENT. 

 a. Fly; b. Larva; c. Pupa the latter from the lower side. ( All enlarged.) 



