Timber Worms
Fig. 25. Work of Timber Worms in Oak. a, work of oak timber worm, Eupsalis minuta; b, barked surface; c, bark; d, sapwood timber worm, Hylocoetus lugubris, and work; e, sapwood.
The character of the work done by this class is shown in [Fig. 25]. The injury consists of pinhole defects in the sapwood and heartwood of felled trees, sawlogs and like material which have been left in the woods or in piles in the open for several months during the warmer seasons. Stave and shingle bolts and closely piled oak lumber and square timbers also suffer from injury of this kind. These injuries are made by elongate, slender worms or larvae, which hatch from eggs deposited by the adult beetles in the outer bark, or, where there is no bark, just beneath the surface of the wood. At first the young larvae bore almost invisible holes for a long distance through the sapwood and heartwood, but as they increase in size the same holes are enlarged and extended until the larvae have attained their full growth. They then transform to adults, and emerge through the enlarged entrance burrows. The work of these timber worms is distinguished from that of the timber beetles by the greater variation in the size of holes in the same piece of wood, also by the fact that they are not branched from a single entrance or gallery, as are those made by the beetles.
Fig. 26. Work of Powder Post Beetle, Sinoxylon basilare, in Hickory Poles, showing Transverse Egg Galleries excavated by the Adult, a, entrance; b, gallery; c, adult.
Fig. 27. Work of Powder Post Beetle, Sinoxylon basilare, in Hickory Pole. a, character of work by larvae; b, exit holes made by emerging broods.