Powder Post Borers
The character of the work of this class of insects is shown in [Figs. 26], [27], and [28]. The injury consists of closely placed burrows, packed with borings, or a completely destroyed or powdered condition of the wood of seasoned products, such as lumber, crude and finished handle and wagon stock, cooperage and wooden truss hoops, furniture, and inside finish woodwork, in old buildings, as well as in many other crude or finished and utilized woods. This is the work of both the adults and young stages of some species, or of the larval stage alone of others. In the former, the adult beetles deposit their eggs in burrows or galleries excavated for the purpose, as in [Figs. 26] and [27], while in the latter ([Fig. 28]) the eggs are on or beneath the surface of the wood. The grubs complete the destruction by boring through the solid wood in all directions and packing their burrows with the powdered wood. When they are full grown they transform to the adult, and emerge from the injured material through holes in the surface. Some of the species continue to work in the same wood until many generations have developed and emerged or until every particle of wood tissue has been destroyed and the available nutritive substance extracted.
Fig. 28. Work of Powder Post Beetles, Lyctus striatus, in Hickory Handles and Spokes. a, larva; b, pupa; c, adult; d, exit holes; e, entrance of larvae (vents for borings are exits of parasites); f, work of larvae; g, wood, completely destroyed; h, sapwood; i, heartwood.