_Timber worms_, Fig. 97. This class of true wood-boring "worms," or grubs, are the larvae of beetles. They enter the wood from eggs deposited in wounds in living trees, from which they burrow deep into the heart-wood. Generation after generation may develop in the wood of a tree without affecting its life but the wood is rendered worthless for most purposes by the so-called wormhole and pinhole defects resulting from their burrows. The same species also breed in the wood of dying and dead standing trees, and in the stumps and logs of felled ones, often for many years after the trees are felled. One species sometimes attacks freshly sawed oak lumber, new stave bolts, etc. They are among the most destructive enemies of hardwood forest trees, especially in reducing the value of the wood of the best part of the trunks. (Hopkins, _Forestry Bulletin_ No. 48, p. 10.) [Illustration: Fig. 97. Work of Timber Worms in Oak: _a_, Work of oak timber worm, _Eupsalis minuta_; _b._ Barked surface; _c._ Bark; _d._ Sap-wood timber worm, _Hylocaetus lugubris_, and its work; _e._ Sap-wood. [_Agric. Year Book_, 1904, Fig. 47, p. 386.]] The _carpenter worms_, Fig. 98. These are large pinkish caterpillars which are the larvae of stout-bodied moths. They enter the bark and wood of living oak, locust, poplar and other trees, from eggs deposited by the moths in the crevices of uninjured bark, or in the edges of wounds. They burrow deep into the solid wood, where they live for two or three years before transforming to the adult. The wood is seriously injured by the very large wormhole defects, and while the life of the tree is but slightly, if at all, affected by the earlier attacks, the continued operations of this class of borers year after year, finally results in the decay of the heart-wood, or a hollow trunk and a dead top. (Hopkins, _Forestry Bulletin_, No. 48, p. 11.) [Illustration: Fig. 98. Worm Holes in Red Oak, Work of the Oak Carpenter Worm. [_Agric. Year Book_, 1903, Fig. 37, p. 324.]]