DEFECTS IN TIMBER CAUSED BY INSECTS 



Fig. 



-Pinholes caused by the pine-wood stainer 

 (Onathot)ichus materiarius) 



POWDER POST 



Powder post is that class of defects in which the larvae of insects 

 reduce the wood fibers of seasoned or partially seasoned wood to 

 a powderlike condition 

 by boring through the 

 wood, which is both 

 their shelter and their 

 food. 



Powder post occurs 

 only in the seasoned or 

 partially seasoned sap- 

 wood or heartwood of 

 both hardwoods and 

 softwoods. Logs, bolts, 

 timbers, lumber, and 

 crude or finished prod- 

 ucts are attacked. The 

 infested wood is al- 

 ways more or less filled 

 with fine or coarse 

 powdery or granulated 

 boring dust and is 

 called powder-posted. 

 This type of injury is 

 dangerous, since the 

 grubs continue their 

 destructive work in the 

 wood and also infest 

 other timber near by. 



DEFECTS CLASSED 

 AS PINHOLES 



The term "pinholes" 

 undoubtedly origi- 

 nated with stave mak- 

 ers and coopers, from 

 the fact that such holes 

 are often plugged with 

 small wooden pins. 

 Pinholes are small, 

 round holes one one- 

 hundredth to one- 

 fourth of an inch in 

 diameter in both the 

 heartwood and sap- 

 wood of hard (broad- 

 leafed) and soft (co- 

 niferous) living trees, 

 green, moist saw logs, 

 bolts, green timbers, or 

 green piled lumber. 

 These holes are made 

 by either ambrosia FlG " 5 -- pinholes ^Jl^f s £ ouslas fir made by 



