30 



BULLETIN 1490, U. S. DEPARTMENT OE AGRICULTURE 



generations over a period of 20 years or more. In certain cases 

 powder-post injury may be a menace to human life, as in the 

 weakened woodwork of buildings, vehicle stock, or ladders. 



Losses due to Lyctus beetles can be prevented by proper methods 

 of classification and piling of stock by kinds ; by keeping heartwood 



Fig. 32. — A, Duali plywood, imported from the Philippine Islands, powder-posted by 

 Bostrychopsis parallela; B, bostrichid powder-post injury to myrtle in Oregon 



and sai:> wood stock separate; by periodical inspection, utilizing the 

 older stock first (34) ; and by using only heartwood piling sticks; 

 or by submergence in water for four months, which renders the wood 

 immune from attack, even after removal from the water. 



In the case of finished wood products, it may often be practicable 

 to treat the wood with substances to prevent attack. Creosotes are 



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