The Aspen Borer and How to Control It. i 
DISTRIBUTION. 
The aspen borer is found in all parts of the country, its distribu- 
tion coinciding with that of the poplar. 
SEASONAL HISTORY AND HABITS. 
Normally this species has but one generation in three years. During 
the latter part of July and during August the adult female beetle 
gnaws in the bark an oblong scar, which slopes toward the center, 
penetrating the cambium or inner bark of the tree. Beneath the 
bark in this scar she deposits one or two eggs (fig. 4), which hatch 
into larve or grubs in from 20 to 25 days. Upon hatching, the young 
Fig. 4.—Aspen borer: a, Egg scar on living aspen trunk; 
b, bark removed to show eggs. 
larva mines beneath the bark, remaining there over winter, and 
entering the sapwood and heartwood the following spring, where it is 
active until May or June of the second year following the egg laying. 
During this time the gallery is enlarged and an opening is main- 
tained through the bark at the place where the egg was laid, and 
through this boring dust is expelled during the feeding period of the 
larva. The accumulation of these piles of fibrous frass at the base of 
the trees is one of the most characteristic features indicating the 
presence of the borer. On reaching full growth the grub (fig. 7) ex- 
cavates the pupal cell near the lower end of the larval mine and re- 
mains inactive in this cell (fig. 5) until the following spring. It then 
pupates and remains as a pupa (fig. 8) 25 to 30 days before transform- 
ing to the adult. During the latter part of July® or during August 
of the third year the adult emerges through the hole which the larva 
used for expelling the frass. 
®In the eastern United States, at an elevation of 500 feet, the beetles emerge from 
four to six weeks earlier.—F. C. C. 
