. Defects in timber caused by insects. Wood; Forest insects. 14 BULLETIN 1490, TJ. S. DEPARTMENT OF AGRICULTURE PINHOLES IX LIVIXG TKEES CAUSED BY TIMBER WORMS Pinholes or wormholes in the heartwood of chestnut and red oak, one one-hundredth to one-fourth of an inch in diameter, open, clear, not stained, but lined with a substance about the color of the wood, a large number of holes in a given space, are made by timber worms hatching from eggs laid in or near scars. The holes made by the grubs are not of uniform size; they may extend several feet through the wood. (Fig. 15.) This defect, due t
. Defects in timber caused by insects. Wood; Forest insects. 14 BULLETIN 1490, TJ. S. DEPARTMENT OF AGRICULTURE PINHOLES IX LIVIXG TKEES CAUSED BY TIMBER WORMS Pinholes or wormholes in the heartwood of chestnut and red oak, one one-hundredth to one-fourth of an inch in diameter, open, clear, not stained, but lined with a substance about the color of the wood, a large number of holes in a given space, are made by timber worms hatching from eggs laid in or near scars. The holes made by the grubs are not of uniform size; they may extend several feet through the wood. (Fig. 15.) This defect, due to the chestnut timber worm,4 is one of the most common and serious defects in chestnut timber throughout its range. It is rare to find chestnut trees, logs, or telephone or telegraph poles free from this defect, and practically every tree of merchantable size is more or less affected. i ,..n,rY'-, k: i. mmii ill*1 ft« mJM 11 r u There is a very low percentage of " clear" chestnut, the re- mainder being " wormy " and reduced to the lower grades. This defect is a " sound wormy " injury and can not be pre- vented. Unfortunately the chest- nut is rapidly becoming extinct as a commercial tree, owing to the chestnut blight fungus. Wormy chestnut and oak wood can be used wherever structural strength is not necessary. They are especially suitable as the base for veneer in manufactur- ing pianos, caskets, coffins, auto- mobile running boards, and the lower grades of building lum- ber, because of the comparatively reasonable price at which this grade of lumber can be bought. Much timber that would other- wise be wasted can be thus uti- lized. There is, however, a limit to the size of the holes ad- mitted. Similar pinholes or wormholes one one-hundredth to one-eighth of an inch in diameter in oak timber (fig. 16) are caused by the oak timber This defect is especially serious in large mature white oak trees. The holes occur in large numbers in a given
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Keywords: ., bookcentury1900, bookdecade1920, bookpublisherwa, booksubjectwood
