﻿58 BULLETIN 1369, U. S. DEPAETMENT OP AGRICULTURE 



vary considerably, but they are usually much larger after the molt 

 to the fifth stage, and measure from 3 to 4.5 millimeters in diameter 

 (fig, 27). It is seldom that any scabbing or other obstruction is 

 found in the aperture over a fifth-stage larva. There is usually to 



Fig. 27. — Close view of portion of cow's back infested with cattle grubs. Hair is 

 clipped from around holes 



be seen a rim of exudate, part of which is considered to be excrement, 

 around the outside edge of each hole. 



The position of the larva is similar to that in the fourth stage. 

 The posterior end of the segments is bent slightly so as to bring the 



