. Defects in timber caused by insects. Wood; Forest insects. 16 BULLETIN 1490, U. S. DEPARTMENT OF AGRICULTURE these long, gal- In Arkansas a 2 per cent loss of the product of green or newly manufactured white-oak Bourbon whisky-barrel staves occurred at one operation. Pinholes one twenty-fifth to one-eighth of an inch in diameter occur in the sap wood of both hardwoods and softwoods (figs. 3, 4, 5, 7, 8, 9, 10, 12, 13, 14); in hardwoods usually the wood is not stained; but in freshly cut green hardwoods the wood may be stained. A few to a large number of holes occur in a given space; often ev
. Defects in timber caused by insects. Wood; Forest insects. 16 BULLETIN 1490, U. S. DEPARTMENT OF AGRICULTURE these long, gal- In Arkansas a 2 per cent loss of the product of green or newly manufactured white-oak Bourbon whisky-barrel staves occurred at one operation. Pinholes one twenty-fifth to one-eighth of an inch in diameter occur in the sap wood of both hardwoods and softwoods (figs. 3, 4, 5, 7, 8, 9, 10, 12, 13, 14); in hardwoods usually the wood is not stained; but in freshly cut green hardwoods the wood may be stained. A few to a large number of holes occur in a given space; often every square inch of wood is penetrated. These common pinhole de- fects in recently felled green logs or bolts (with or with- out the bark) and closely piled green timber and lumber are caused by am- brosia beetles8 (figs. 4 and 5). There are two types of gal- leries made by beetles—one, a winding main lery and usually no staining of the wood, and the other, a se- ries of short side galleries at right an- gles to this main gallery (figs. 1 and 6), the gallery usu- ally being accompa- nied by a staining of the wood. Unlike holes made by the timber worms, which increase with the growth of the worms, these holes are more or less uniform in size. PINHOLES IN FELLED TREES CAUSED BY TIMBER WORMS Pinholes caused by timber worms in the heartwood of chestnut 9 and oak 10 can be recognized as follows: Holes from one one-hun- dredth to one-fourth of an inch in diameter; open and not stained; a large number to a given space. Such holes may be a serious defect in square timbers used in struc- tures the woodwork of which is exposed to the weather. Care should be exercised in utilizing wormy oak in structural work where strength is required, or in vehicle, ladder, or implement stock. It should be. Fig. 17.—Pinholes in yellow birch caused by the sapwood timber worm (Hylecoetus lugubris). ' (Drake) 8 GnatJiotrichus and Xyloterus. 9 The larvae of 31 elitt omnia sericeum Harris cause wormy ches
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Keywords: ., bookcentury1900, bookdecade1920, bookpublisherwa, booksubjectwood
