154 THE OAK. 



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, etc., as they pass into the pupa 

 stage in July. The denudation of the leaves brought 



FIG. 40. Tortrix viridana, the preen 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 devel- 

 oped. 



