370 INSECTS. 



herself, but care for her progeny, the motive of her 

 approach. 



The Botflies all deposit their eggs on or in the bodies 

 of various quadrupeds, some species choosing one part 

 and some another, but each species of Fly being constant 

 both to the one species of quadruped and to one part of 

 its body. 



The Botflies are large and hairy-bodied, and carry their 

 wings extended. (Estrus Bovis, the Ox Botfly, is about 

 half an inch in length ; the legs are long and strong, and 

 the alulse very large. It is of a blackish brown colour, 

 banded with black and coloured hairs. On the face the 

 hairs are reddish, and pale yellowish on the head. The 

 thorax is streaked with reddish hairs, and the base of the 

 abdomen is clothed with the same colour, the tip being 

 orange red. 



The habit of this insect is to deposit its eggs, singly, 

 in holes which it perforates, with an auger-like ovipositor, 

 in the backs of oxen and other horned cattle. The egg 

 thus placed causes a large open tumour, in which the 

 larva resides until ready for the pupa change, when it 

 emerges, falls to the ground, and there undergoes its 

 metamorphosis. 



The Botfly of the sheep, Cephalemyia ovis (PI. XVI., 

 fig. 5, 5 a), lays its eggs in the nostrils of its victim, 

 whence the larvae creep farther into the head, sometimes 

 with fatal effect upon the animal. It is to avoid the 

 attacks of this Fly that sheep may be seen holding their 

 noses in the dust, in ruts, or dusty places, or stamping 

 and shaking their heads, or running violently about the 

 field. This Fly is about the same length as the former, 

 but the legs are much smaller and less powerful. It is 

 of a dark colour, chequered with hoary hairs. 



