OPLARS, aspens, and cottonwoods, which are 
widely distributed over the United States, are 
everywhere subject to serious injury by wood-boring 
insects. One of the chief of these is the aspen borer, 
which feeds in the trunks or larger branches, so 
weakening the wood that the tree is readily broken 
off by windstorms. Plantations for paper pulp are 
often completely destroyed. 
This bulletin gives methods of controlling the 
aspen borer or reducing its damage to a minimum. 
It is based on extensive studies made in the Pikes 
Peak region of Colorado, but the data in general 
apply to all regions of the United States where the 
poplars are native. The introduced Lombardy pop- 
lar is very seldom injured, but the commercial cot- 
tonwood of the Mississippi Valley seems to be the 
only native species of poplar which is at all immune 
to the attack of this insect. 
Contribution from the Bureau of Entomology 
L. 0. HOWARD, Chief 
Washington, D. C. October, 1920 
