4 Farmers’ Bulletin 1154. 
100 feet in height, with clean, sound trunks without a limb for 50 feet. 
These trees are from 65 to 100 years of age. (Figs. 1 and 2.) 
The common aspen * comes up from seed scattered broadcast by the 
wind, and is an exceedingly valuable cover for watersheds and areas 
devastated by fire. It acts as a nurse to conifers which succeed it. 
The wood is used for fruit boxes, fence posts, and poles, and, when 
sound and free from insect work, for props and cribbing in coal mines. 
Of late years it is being used to a great extent for cabins and summer 
homes. (Fig. 3.) 
Fie 1.—Aspen growing in mixture with Douglas fir and 
Engelmann spruce, on Cheyenne Mountain, Colo., at an 
elevation of 9,000 feet. 
The wood of the poplars is one of the materials used for pulp mak- 
ing. The trees are largely planted for shade and ornament, for wind- 
breaks, and to hold the banks of streams. 
CHARACTER AND EXTENT OF INJURIES. 
The primary work of the aspen borer begins with an oblong scar 
made by the adult in the bark of living, healthy, and injured trees, 
in which the eggs are deposited, as shown in figure 4. The tiny grub 
or larva on hatching from the egg at once begins its destructive work 
by feeding and mining between the bark and wood, in which it re- 
4 Populus tremuloides, 
