DEFECTS IN TIMBER CAUSED BY INSECTS 



13 



A loss of $5 to $20 per 

 thousand feet of timber 

 is a conservative esti- 

 mate. This defect is 

 classed as " wormholes, 

 no living worms or de- 

 cay," and can not be pre- 

 vented in the tree, but of 

 course similar defects in 

 the green stock can be 

 prevented by proper 

 handling. 



Pinholes one twenty- 

 fifth to one-eighth of an 

 inch in diameter in both 

 heartwood and sapwood 

 of hardwoods and soft- 

 woods (figs. 1, 3, 4, 5, 6, 

 7, 8, 9, 10, 11, 12, 13, and 

 11) are caused by similar 

 beetles. 3 



The defects caused by 

 these pinholes and stains 

 (discolored streaks and 

 patches) (figs. 1, 2, 3, 4, 

 6, 9, and 13) reduce the 

 grade of timber and its 

 full strength, unfitting it 

 for structural timber, wagons, agricultural implements, tight cooper- 

 age, and shingles. A 25 per cent loss of elm cooperage stock in 



logs at the mills in 

 Illinois was due to 

 such defects. In 

 some cases millions 

 of feet of timber have 

 been reduced 10 to 25 

 per cent or more in 

 value by pinhole de- 

 fects. In deadened 

 standing cypress in 

 the Gulf States, pin- 

 hole injury can be 

 prevented by gir- 

 dling the trees in 

 March, April, Oc- 

 tober, and Novem- 

 ber (°28), but from 

 August to Septem- 

 ber is apparently 



Fig. 14. — Pinhole damage by ambrosia beetles < Xyleborus the 1110 St effective 

 grenadensis) to Hura wood (Rakuda) imported from Ceu- 

 tral America season. 



Fig. 13. — Pinholes caused by ambrosia beetles (Xyle- 

 borus sp.) in imported greenheart (Xectandra 

 rodioei) 



3 Platypus, Monarthrum, Xyleborus. 



