The carpenter worms, Fig. 98. These are large pinkish caterpillars which are the larvae of stout-bodied moths. They enter the bark and wood of living oak, locust, poplar and other trees, from eggs deposited by the moths in the crevices of uninjured bark, or in the edges of wounds. They burrow deep into the solid wood, where they live for two or three years before transforming to the adult. The wood is seriously injured by the very large wormhole defects, and while the life of the tree is but slightly, if at all, affected by the earlier attacks, the continued operations of this class of borers year after year, finally results in the decay of the heart-wood, or a hollow trunk and a dead top. (Hopkins, Forestry Bulletin, No. 48, p. 11.)
Fig. 98. Worm Holes in Red Oak, Work of the Oak Carpenter Worm. [Agric. Year Book, 1903, Fig. 37, p. 324.]
Columbian Timber-beetle One of the commonest wormhole defects in white oak, rock oak, beech, and tulip ("whitewood" or "yellow poplar") is one known to the lumber trade as grease spots, patch-worm, or black holes, Fig. 99, steam boats, Fig. 100, etc., caused by the Columbian timber beetle (Corthylus columbianus Hopk.) The characteristic feature of this wormhole defect, which will enable it to be readily recognized in oak and beech, is transverse series of two or more black holes about the size of the lead in an ordinary lead pencil, with a streak of stained wood extending with the grain two or three or more inches each side, as in Fig. 99. In quarter-sawed oak or split or sawed staves, a short longitudinal section of one of these black holes is seen attended by the stained streak on one side of a thick or curly growth or grain, Fig. 100. It is this form which is called "steamboats." In whitewood (yellow poplar) the black holes are attended by very long black, greenish, or bluish streaks, sometimes five or six feet long. When this is common in the lumber it is called "calico poplar." Fig. 101 represents the characteristic appearance of this defect greatly reduced. (Hopkins, Agric. Yr. Bk., 1903, p. 327.)
Fig. 99. Work of the Columbian Timber Beetle: Black holes and "grease spots" in white oak. [Agric. Year Book, 1903, Fig. 38, p. 325.]
Fig. 100. Work of the Columbian Timber Beetle: "Steamboats" in quartered or Split white oak. [Agric. Year Book, 1903, Fig. 39, p. 326.]
Fig. 101. Work of the Columbian Timber Beetle in Tulip Wood, "Calico Poplar," [Agric. Year Book 1903, Fig. 40, p. 326.]