16 



BULLETIN 1490, U. S. DEPARTMENT OF AGRICULTURE 



these 

 long, 



gal- 



In Arkansas a 2 per cent loss of the product of green or newly 

 manufactured white-oak Bourbon whisky-barrel staves occurred at 

 one operation. 



Pinholes one twenty-fifth to one-eighth of an inch in diameter 

 occur in the sap wood of both hardwoods and softwoods (figs. 3, 4, 

 5, 7, 8, 9, 10, 12, 13, 14) ; in hardwoods usually the wood is not 

 stained ; but in freshly cut green hardwoods the wood may be stained. 

 A few to a large number of holes occur in a given space ; often every 



square inch of wood 



is penetrated. These 

 common pinhole de- 

 fects in recently 

 felled green logs or 

 bolts (with or with- 

 out the bark) and 

 closely piled green 

 timber and lumber 

 are caused by am- 

 brosia beetles 8 (figs. 

 4 and 5). There are 

 two types of gal- 

 leries made by 

 beetles — one, a 

 winding main 

 lery and usually no 

 staining of the wood, 

 and the other, a se- 

 ries of short side 

 galleries at right an- 

 gles to this main 

 gallery (figs. 1 and 

 6), the gallery usu- 

 ally being accompa- 

 nied by a staining of 

 the wood. Unlike 

 holes made by the 

 timber worms, which 

 increase with the growth of the worms, these holes are more or less 

 uniform in size. 



PINHOLES IN FELLED TREES CAUSED BY TIMBER WORMS 



Pinholes caused by timber worms in the heartwood of chestnut 9 

 and oak 10 can be recognized as follows : Holes from one one-hun- 

 dredth to one-fourth of an inch in diameter ; open and not stained ; a 

 large number to a given space. 



Such holes may be a serious defect in square timbers used in struc- 

 tures the woodwork of which is exposed to the weather. Care should 

 be exercised in utilizing wormy oak in structural work where strength 

 is required, or in vehicle, ladder, or implement stock. It should be 



Fig. 17. — Pinholes in yellow birch caused by the sapwood 

 timber worm (Hylecoetus lugubris) . ' (Drake) 



8 GnatJiotrichus and Xyloterus. 



9 The larvae of 31 elitt omnia sericeum Harris cause wormy chestnut and oak; the eggs 

 are laid under bark. 



10 The larvae of Eupsalis mi nut a Drury cause wormy oak; the eggs are laid under bark. 



