. Seasoning of wood; a treatise on the natural and artificial processes employed in the preparation of lumber for manufacture . taina much larger size. The diameter of the holes made byeach species corresponds closely to that of the body, andvaries from about one-twentieth to one-sixteenth of aninch for the tropical species. Round-headed Borers The character of the work of this class of wood- and bark-boring grubs is shown in Fig. 24. The injuries consistof irregular flattened or nearly round wormhole defectsin the wood, which sometimes result in the destruction 102 SEASONING OF WOOD of valuab
. Seasoning of wood; a treatise on the natural and artificial processes employed in the preparation of lumber for manufacture . taina much larger size. The diameter of the holes made byeach species corresponds closely to that of the body, andvaries from about one-twentieth to one-sixteenth of aninch for the tropical species. Round-headed Borers The character of the work of this class of wood- and bark-boring grubs is shown in Fig. 24. The injuries consistof irregular flattened or nearly round wormhole defectsin the wood, which sometimes result in the destruction 102 SEASONING OF WOOD of valuable parts of the wood or bark material. The sap-wood and heartwood of recently felled trees, sawlogs,poles, posts, mine props, pulpwood and cordwood, alsolumber or square timber, with bark on the edges, andconstruction timber in new and old buildings, are injuredby wormhole defects, while the valuable parts of storedoak and hemlock tanbark and certain kinds of wood areconverted into worm-dust. These injuries are causedby the young or larvae of long-horned beetles. Thosewhich infest the wood hatch from eggs deposited in the. Fig. 24. Work of Round-headed and Flat-headed Borers in Pine, a, workof round-headed borer, sawyer, Monohammus spiculatus, naturalsize; b, Ergates spiculatus; c, work of fiat-headed borer, Bwprestis,larva and adult; d, bark; e, sapwood; /, heartwood. outer bark of logs and like material, and the minute grubshatching therefrom bore into the inner bark, throughwhich they extend their irregular burrows, for the purposeof obtaining food from the sap and other nutritive materialfound in the plant tissue. They continue to extend andenlarge their burrows as they increase in size, until theyare nearly or quite full grown. They then enter the woodand continue their excavations deep into the sapwood orheartwood until they attain their normal size. Theythen excavate pupa cells in which to transform into adults, ENEMIES OF WOOD 103 which emerge from the wood through exit
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