DEFECTS IN TIMBER CAUSED BY INSECTS 



17 



rejected for barrel staves and heads of tight cooperage, unless the 



holes are few and can be plugged. Such stock can be used where the 



holes can be plugged, 



puttied, and painted 



over, or as a base for 



veneer. 



Pinholes or worm- 

 holes one one-hun- 

 dredth to three-six- 

 teenths of an inch in 

 diameter in green saw 

 logs with the bark on, 

 of basswood, buckeye, 

 chestnut, black wal- 

 nut, cottonwood, yel- 

 low poplar, and birch 

 (fig. 17), are caused 

 by the sapwood tim- 

 ber worm, 11 which 

 may cause a 5 to 10 

 per cent loss of a log. 

 This defect is de- 

 scribed as " worm- 

 holes, no living worms 

 or decay," and can be 

 prevented. 



The insect lays its 

 eggs in dying trees 

 and green saw logs 

 which are allowed to 

 lie in the woods with 

 the bark on from 

 April to July, in the 

 States north of the 

 Gulf. The eggs are 

 deposited in crevices 

 in the bark. The 

 beetle will not lay 

 its eggs in barked logs 

 or logs which are 

 floating in log ponds. 



In the sapwood or 

 heartwood of oak, ma- 

 ple, tupelo gum, and 

 beech, grouped holes 

 from one-eighth to 

 three-sixteenths of an 

 inch in diameter and 

 all more or less connected by irregular blackened streaks are caused 

 by tenebrionid timber worms. 12 



^Hylecoetus lugiibris Say. 



12 The larvae of Strongylium spp. cause wormholes in hardwoods. 



38252°— 27 3 



Fig. 18. — Holes caused by termites (Coptotermes niger) 

 in log imported from Honduras ; damage to the living 

 tree caused this defect in the board 



