_Bark_ and _wood borers_, Fig. 94. This class of enemies differs from the preceding in the fact that the parent beetles do not burrow into the wood or bark, but deposit their eggs on the surface. The elongate, whitish, round-headed (_Cerambycid_), flat-headed (_Buprestid_), or short, stout (_Curculionid_) grubs hatching from these eggs cause injury by burrowing beneath the bark, or deep into the sap-wood and heart-wood of living, injured and dead trees, sawlogs, etc. Some of the species infest living trees, Fig. 95, causing serious injury or death. Others attack only dead or dying bark and wood, but this injury often results in great loss from the so-called wormhole defects. (A. D. Hopkins, _Entom. Bull._, No. 48, p. 10.) [Illustration: 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.]] [Illustration: 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.) [Illustration: 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.]]