8 



farmers' bulletin 178. 



caused by these beetles in this country has amounted to hundreds of 

 thousands of dollars annually. The loss increases with the length 

 of time the infested stock is held in storage. In certain cases 

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

 ened wood material of vehicles, ladders, etc. 



CHARACTER OF THE INSECTS WHICH CAUSE THE DAMAGE. 



The Lyctus beetles are small, slender, somewhat flattened, brownish 

 to nearly black beetles, which, upon emerging from the wood where 



Fig. 4. — Powder-postid white ash shipbuilding lumber, showing burrows of larvae and 

 exit holes of adult Iteetles ; board from closely piled stack of lumber throughout which 

 larviE had burrowed; work of Lyctus planicoUis. (Original.) 



they breed and pass the winter as larva?, fly or crawl about in search 

 of suitable wood material in which to deposit their eggs. 



HABITS AND SEASONAL HISTORY OF LYCTUS BEETLES. 



There are four stages in the life history of these insects — namely, the 

 egg, the larva or grub, the pupa or resting stage, and finally the 

 adult or beetle. 



The egg (fig. 7) is deposited in the pores of the wood by the female 

 beetle soon after it emerges from the wood. The minute larva which 

 hatches from the egg proceeds to burrow in and through the wood in 

 all directions, feeding and growing as it proceeds, until it has 

 attained its full size. The full-grown larva (fig. 8) is a yellowish- 

 white grub ranging in length from one-eighth to one-fifth of an inch, 



