of various kinds. The caterpillars of certain moths (especially Cnethocampa and Tortrix), for instance, eat off the loaves in June, and then form large masses of mingled débris, skins, etc., as they pass into the pupa stage in July. The denudation of the leaves brought
Fig. 40.—Tortrix viridana, the green oak-moth, the larvæ 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.