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BULLETIX 1490, U. S. DEPARTMENT OF AGRICULTURE 



The rejection of timber with insect defects caused in the tree, log, 

 or green lumber before the- wood is dry or seasoned is often an 

 avoidable loss, because the insects are no longer working in the wood. 

 This type of insect defect is analogous to " pecky cypress " caused 

 by a fungus. Even though the defects are such that they materially 

 affect the strength of the wood or otherwise unfit it for the special 



use intended, there are still 

 many purposes for which it 

 can be used. The grade may 

 be merely lowered, according 

 to the number and size of the 

 holes; or the defect may unfit 

 the wood for special uses, 

 owing to unsightly appear- 

 ance, likelihood to cause leaks 

 (as for barrel staves and heads 

 for tight cooperage), or weak- 

 ening (as for high-grade air- 

 plane stock). Much waste can 

 be avoided by utilizing such 

 defective timber for other uses 

 and in lower grades than origi- 

 nally intended. 



Damaged implement or ve- 

 hicle stock and other material 

 in which great structural 

 strength is required can be 

 used for less exacting purposes, 

 the defect being plugged and 

 painted over; while low-grade 

 lumber with wormholes but no 

 living worms or decay can be 

 used as the base for veneer if 

 the holes are not large enough 

 to cause depressions in the face 

 veneer. On the other hand, the 

 acceptance of material infested 

 by powder-post beetles may 

 lead to serious results through 

 a break at a critical moment. 

 Special reference is made in 

 this bulletin to the protection 

 and conservation of both crude and finished wood products, such as 

 lumber, bolts, cooperage stock (finished and unfinished), agricultural- 

 implement handles, tent poles, vehicle parts, timber for shipbuilding, 

 oars, airplane stock, and other high-grade products. 



TYPES OF INSECT DEFECTS; DEFINITIONS 



The principal types of defects caused by insects may be classed in 

 three definite groups, namely, pinholes, grub holes, and powder post. 

 (Table 1.) The terms for these defects are those generally used by 

 the loggers in the woods and the sawyers and graders at the mill. 



Fig. 2. — " Calico poplar," a defect caused by 

 an ambrosia beetle (Corthylus columbi- 

 anus). (25) 



