. An annotated list of the important North American forest insects. Forest insects. o BULLETIN 1490, U. S. DEPARTMENT OF AGRICULTURE PINHOLES Pinholes are small, round, usually open holes ranging from one one-hundredth to one-fourth of an inch in diameter; they are made either by ambrosia beetles or timber Avorms. Pinholes caused by ambrosia beetles are of two types: (1) Pinholes caused by adult beetles boring into the trunks of growing trees for the purpose of laying eggs and rearing their young, or by larvae, which also may burrow in the wood; (2) pinholes made by adult beetles or larvae in
. An annotated list of the important North American forest insects. Forest insects. o BULLETIN 1490, U. S. DEPARTMENT OF AGRICULTURE PINHOLES Pinholes are small, round, usually open holes ranging from one one-hundredth to one-fourth of an inch in diameter; they are made either by ambrosia beetles or timber Avorms. Pinholes caused by ambrosia beetles are of two types: (1) Pinholes caused by adult beetles boring into the trunks of growing trees for the purpose of laying eggs and rearing their young, or by larvae, which also may burrow in the wood; (2) pinholes made by adult beetles or larvae in freshly felled green saw logs (with or without the bark on), bolts, and green or partly seasoned lumber. In commercial grading rules for various species of timber pin- holes constitute a standard defect (considering only w^ormholes), but are sometimes recognized as "equivalent defects," that is, equivalent. Fig. 3. -Work of ambrosia beetles in both sapwood and hrartwooU nf southoru yeUow pine to other defects, such as knots. This grade in certain hardwoods is termed " sound wormy " and is of that class of defects in timber or lumber in Avhich the insects are no longer present and hence no fur- ther damage results to the timber. GRUB HOLES Grub holes or the larger wormholes are oval, circular, or irregular holes three-eighths of an inch to 1 inch in diameter, produced by adult insects (1) boring into or laying eggs in the trunks of living trees, or (2) boring into green, recently felled logs for the purpose of laying eggs or rearing their young; the young or larvae cause most of the injury to the wood, Avhich serves as both food and shelter. Grub holes may also be classified as standard Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Craighead, Frank C. (Frank Cooper), 1890-; Per
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Keywords: ., bookauthorhopkinsadandrewdelmar, bookcentury1900, bookdecade1900
