Aylotrechus obliteratus LeC., the poplar-butt borer, a serious 
pest of aspen and other poplars in the Rocky Mountain region, 
also occurs in many parts of eastern United States. The adult is 
dark-colored and about 10 to 18 mm. long. The thorax is crossed 
by yellow bands at the front and rear margins; the elytra are 
crossed by three yellow bands—the first one oblique, the middle 
one curved, and the last one transverse. 
Adults are present during late summer. Eggs are deposited in 
irregularities of the bark or exposed wood, and the larvae feed 
beneath the bark until fall. The following year they bore into the 
wood where they feed for several years, much of the time in parts 
of the tree below the ground line. Females continue to deposit 
eggs in the butts of infested trees until the wood is completely 
honeycombed and the tree dies or is broken by wind or ice. 
Xylotrechus sagittatus (Germ.) breeds in dead conifers in 
eastern Canada and the Northern States. In areas where pines 
predominate, it is especially common. Logs, slash and trees killed 
by fire or bark beetles are particularly attractive. Adults (fig. 69) 
are dark brown and about 18 mm. long. Each elytron is marked 
with variable stripes of fine gray hairs—one stripe along the 
sutural margin, one along the outer margin, and one at the apex. 
The larvae feed first beneath the bark, then they tunnel deep into 
the wood. 
The rustic borer, Xylotrechus colonus (F.), one of the com- 
monest of all cerambycids in eastern United States, feeds under 
the bark of almost all dead hardwoods. It occurs also in southern 
COURTESY OF DUKE UNIV. SCH. OF FOREST. 
FIGURE 69.— Adult of 
Xylotrechus sagittatus. 
COURTESY OF DUKE UNIV. SCH. OF FOREST. 
FIGURE 70.—Adult of the rustic 
borer, Xylotrechus colonus. 
202 
