EXPLANATION OF PLATE XV. 
Section of wood cylinder from which the bark has been 
removed all but a thin layer of young bast, showing the course of 
the larva through the latter from the point when, having penetrated 
the entire bark from the outside where the egg was laid, it reaches 
the surface of the wood cylinder (a.4.A.). Continuing to feed 
upon the soft bast and cambium layer, and grazing superficially the 
sapwood, finally, if it does not pupate in the bark, it enters the wood 
for pupation by an elliptical hole (B.B.). 
Nat. size. 
