169 MISC. PUBLICATION 273, U. S. DEPT. OF AGRICULTURE 
in the wood from which fine powder exudes are a good indication of 
their presence. 
Favorable conditions for attack are made when the sapwood of 
fine-quality hardwoods, especially of hickory, ash, and oak, is 
allowed to season for 2 or 3 years in endieeurier piles. Accumula- 
tions of old stock, refuse, and useless material greatly increase the 
hazard of infestation. Species of hardwood ordinarily not subject 
to the attack of these insects will, if piled with more favorable host 
species, share the damage of infestation. It is, therefore, evident 
FIGURE 80.—Wood showing holes made by Lyctus beetles. 
that proper methods of handling will do much to prevent these de- 
structive pests from becoming established. Material should be 
inspected and rehandled annually, and all sapwood refuse, as well 
as stock showing signs of infestation, should be burned. Woods of 
different species should be piled separately and should be classified 
according to age of seasoning, in order that a constant turn-over in 
yard s tocks may be maintained | by utilizing or disposing of the long- 
est-seasoned stock first. The use of heartwood instead of sapwood 
for piling sticks in the yard also helps to reduce the breeding ground. 
Kiln drying and steaming under pressure have produced gratifying 
control. An undesirable feature of the steam- -pressure methods is 
that it is hable to lower the structural strength of the wood, and also 
there is danger of causing discoloration. 
Stout’s bostrichid (Polycaon stouti Lec.) is a large black beetle 
about three-fourths of an inch long, with prominent mandibles. The 
larvae bore in the wood of various hardwoods such as oak, eucalyp- 
tus, maple, California laurel, madrofia, sycamore, and other trees in 
California. In several cases these large beetles have emerged from 
