NON -MIGRATORY LARVJE 337 



larva breaks through the upper or cephahc pole of the egg. It 



gradually works the remains of the chorion and vitelline membrane 



over its body to the anal extremity, where they persist as a 



crumpled annular base of attachment to the leaf. With the 



approach of a moving object, the larva stands erect within the 



cup-like base referred to, and its whole body rotates vigorously 



in the efforts made by the parasite to obtain a hold on the object 



in its vicinity (Fig. 79). If it be a cutworm, the parasite speedily 



bores through the integument, and in a few minutes it has passed 



within its host with the exception of its spiracular extremity, 



which rests in the original perforation, in free 



communication with the outside air. An 



integumental sheath grows around the larva 



and, maintained in this position, it completes 



its development at the expense of the blood 



and the fat-body of the host. 



This stationary habit prevails in the group 



Echinomyiinse whose members are essentially 



parasites of caterpillars {vide Thompson, 1923). 



The primary larvae are well adapted to remain ~ ^^'~ 



on the host food-plant for considerable periods, Fig. 79. Newly 



J j.i_ij-£j' j.-ii. r hatched larva of 



and are notably different m structure from Panzeria rudis 



those which live within their hosts at a attached to 



correspondingly early stage. The integument [^^"rjFronrpiell!) 



is tough, resistant and deeply coloured with 



an armature of scale-like plates and spines. Thus equipped they 



are not only able to resist desiccation, but are also enabled to hold 



on to and bore a way rapidly into their hosts. 



According to Strickland the larva of Bomietia may leave its 

 cup-like basal pad and migrate a short distance to assume again 

 its erect position. This apparently insignificant feature is 

 noteworthy, since species with sedentary primary larvae intergrade 

 with others like Digonochcuto (p. 334) whose larvae are actively 

 migratory. 



Group B. The habit of depositing eggs externally on the body 

 of the host, which hatch into ectoparasitic larvae, is of common 

 occurrence among Chalcids and Ichneumonoids. It is, however, 



