the second summer of their lives, they bore either directly upward or downward and 
pupate in cells at the end of their tunnels. Infested trees are never killed outright but 
are seriously weakened, becoming subject to windbreakage. 
Xylotrechus obliteratus LeConte, the poplar-butt borer, a serious pest of quak- 
ing aspen and other poplars in the Rocky Mountain region, also occurs in many 
parts of the 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 sagittatus (Germar) breeds in dead conifers from eastern 
Canada and the Northeastern States to Florida and New Mexico. In areas where 
pines predominate, it is especially common. Logs, slash, and trees killed by fire or 
bark beetles are particularly attractive. Adults (fig. 141) are dark brown and from 
12 to 21 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. 
Courtesy Duke Univ. Sch. For. 
Figure 141.—Adult of Xy/otrechus sagittatus 
Sagittatus. 
311 
