260 



INSECTS AFFECTING DOMESTIC ANIMALS. 



for pupation a*- *lirnvn at v l, and soon change to the 

 pupa or chrysalis state, represented at £- About a 

 month later they emerge as adult flies, one of which 

 is represented, natural size, at <C- These flies pair, 

 and the females deposit eggs on the backs of cattle. 

 The eggs hatch into grubs that work their way into 

 the skin, where they form the warble cells. Their 

 mouth parts irritate the flesh, causing an ulceration, 



c d 



Fig. 136. Ox Warble Fly : a, larva ; b, pupa : c, fly ; d, section of warble.''* 



which not only is distressing to the animal, but in- 

 jures the hide and beef, and, in the case of dairy ani- 

 mals, lessens the quantity of milk produced. 



Tlie beef beneath these warbles has a peculiar, 

 diseased, sickening appearance, and is commonly 

 called " licked beef." Such beef always commands 

 a lower price than that which is unaffected. 



Remedies. — Every warble maggot destroyed in 

 spring before it escapes to the ground to pupate, 



