Fig. 94. Work of Round-Headed and Flat-Headed Borers in Pine: a, Work of round-headed borers, "sawyer," Monohamnus sp.; b, Ergates spiculatus; c, Work of flat-headed borer, Buprestis, larva and adult. [Agric. Year Book, 1904, Fig. 46, p. 385.]
Fig. 95. Hemlock Killed by Buprestid Worms. Hoquiam, Washington. U.S. Forest Service.
The pine sawyers are among the most troublesome pests in the mill yard, and their large, white larvae often do much damage to logs by eating great holes thru their solid interior. While burrowing in the wood the larvae make a peculiar grating sound that may be heard on quiet nights at a considerable distance. This is a familiar sound in the lumber camps of the North, and has probably given rise to the name of the pine sawyers by which these insects are known. (Forestry Bulletin, No. 22, p. 58.)
Powder-post beetles, Fig. 96. This is a class of insects representing two or three families of beetles, the larvae of which infest and convert into fine powder many different kinds of dry and seasoned wood products, such as hickory and ash handles, wagon spokes, lumber, etc., when wholly or in part from the sap-wood of trees. Oak and hemlock tan-bark is sometimes injured to a great extent, and the structural timbers of old houses, barns, etc, are often seriously injured, while hop poles and like products are attacked by one set of these insects, the adults of which burrow into the wood for the purpose of depositing their eggs. (Hopkins, Forestry Bulletin No. 48, p. 11.)
Fig. 96. Work of Powder Post Beetle, Sinoxylon basilare, in hickory pole: a, Character of work by larvae; b, Exit holes made by emerging broods. [Agric. Year Book, 1904, Fig. 49.]
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.)
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.]