DEFECTS IX TIMBER CAUSED BY INSECTS 



31 





■■B 







;. 







•.;■ ■ 







Fig. 33. — Holes made by the banded ash borer 

 (Xeoclytus capraea), one of the powder-post beetles 



effective preventives, but they stain the wood; hence, where they 

 can not be used, in the light of the discovery of the place and 

 manner of the laying 

 of the eggs in the 

 pores of the wood, 

 any substances that 

 will close the pores 

 will prevent oviposi- 

 tion in wood not pre- 

 viously infested. In 

 wood from which bee- 

 tles have emerged, 

 however, eggs might 

 be laid within the exit 

 holes. Paraffin wax. 

 varnish, linseed oil, or 

 other fillers effectively 

 close the pores of 

 wood. A certain var- 

 nish known as hard- 

 ened gloss oil is com- 

 monly used. Wood 

 that has been sea- 

 soned less than 8 to 

 10 months will not 

 be attacked by Lyctus 

 beetles ; therefore, in 

 applying chemical 

 preventives, only sap- 

 wood that has been 

 seasoned for 8 to 10 

 months and longer 

 need be treated. The 

 seasonal history of 

 these beetles indicates 

 that preventives 

 should be applied be- 

 fore March 1. 



The great and re- 

 curring expense of 

 treating infested wood 

 can be avoided by 

 prevention of attack 

 by proper methods of 

 management. Since 

 only the sapwood or 

 whitewood is attacked 

 by Lyctus powder-post 

 beetles, it is recom- 

 mended that more 

 heartwood be used to 

 replace sapwood. Although the demand of the trade is for white- 

 wood handles, etc., the prejudice against heartwood is not warranted 



Fig. 34. — Powder-posted ash shipbuilding lumber, show- 

 ing coarse powdery frass in the burrows made by 

 Xeoclytus capraea 



