154 THE OAK 



Much mischief is effected by the attacks of insects 

 of various kinds. The caterpillars of certain moths 

 (especially Cnethocampa and Tortrix), for instance, eat 

 off the leaves in June, and then form large masses of 

 mingled debris, skins, &c., as they pass into the pupa 

 stage in July. The denudation of the leaves brought 



FIG. 40. Tortrix viridana, the green oak- moth, the larvae 

 of which eat off the young leaves. (Altum.) 



about by such caterpillars is apt to be very exhaustive 

 to the trees, for although they put forth new foliage in 

 July and August, it must not be forgotten that these new 

 leaves are constructed from materials which should have 

 gone to the general stores in the tree, and from which 

 new wood, for instance, would have been developed. 



