30 HISTORY OF INSECTS. 



Sheep are exceedingly annoyed by these flies, and to 



avoid them lie down in 

 ruts with their heads close 

 to the ground ; at other 

 times we see them huddled 

 together under trees in a 

 dense mass or phalanx, the 

 nose of each being pushed 

 into the fleece of another. 



There is a third species 

 of breeze-fly, far more formi- 

 dable than either of those previously described : its eggs 

 are laid on the backs and sides of cows and oxen, and the 

 larvae hatched from them enter the hide, producing tumours 

 as large as pigeons' eggs. The larva itself is of an oblong 

 figure, larger at one extremity than at the other : the body 

 is divided into ten or twelve segments by transverse bands, 

 and these are again intersected by six longitudinal lines, 

 Avhich purse up the skin, and produce along the sides 

 a series of mammiform protuberances, each possessing 

 at its extremity a respiratory pore : on each segment 

 of the body may be obser^^ed ridges, or dotted promi- 

 nent lines, interrupted however by the longitudinal lines 

 already noticed : there are in pairs a narrower and broader 

 Une of minute dots or points ; the narrower line is found, 

 under a lens, to be formed of hooks bent towards the pos- 

 terior extremity of the insect; the broader lines consist 

 of smaller hooks bent in an opposite direction, or towards 

 its head : it is probably by the aid of these hooks that the 

 animal raises or dej)resses itself in the tumour, and finally, 

 when mature, effects its escape. 



The food of the larva appears to be the pus or matter 

 surrounding it in the tumour in which it exists : as 

 regards the period of its continuing to feed we have little 



