The southern pine beetle adult (fig. 160A) is reddish brown to black and from 2.2 
to 4.2 mm long. The front of the head has a distinct longitudinal median groove 
bordered by a narrow elevation of tubercles on each side; the pronotum is slightly 
narrowed at front, broadest at the middle, and about as long as wide; the elytra are 
as wide as and over twice as long as the pronotum; and the declivity is convex. The 
full-grown larva is a whitish, legless grub with a glossy reddish-brown head, and it 
is about 5 mm long. 
A B 
F=Dol2or 
Figure 160.—The southern pine beetle, Dendroctonus 
frontalis: A, adult; B, pitch tubes on shortleaf pine; C, 
winding egg galleries. 
Winter is spent in the bark in all stages—egg, larval, pupal, and adult. 
Emergence in the spring varies with the overwintering stage, geographic location, 
and climatic conditions. In the southern Appalachians, the overwintering adults 
emerge about mid-April, while those that develop from overwintering eggs may not 
appear until late June. The bark of trees through which the adults have emerged is 
peppered with small, round holes. Hibernating beetles do not attack healthy, living 
trees after they emerge. Instead, they seek out and invade trees attacked but not 
killed the previous fall (590). Generally, beetles attack the middle and upper trunk 
first, especially in the Middle Atlantic States. Later they continue their attacks 
down the trunk to within 1.5 m or less of the ground. In the Deep South, 
overwintering adults emerge during warm periods in the winter and may attack the 
upper and lower portions of the tree from which they emerged. However, most of 
these beetles emerge in late February or early March and first attack the mid to 
lower trunk of new host trees. Continuing attacks extend the zone of attack down to 
the ground line and up into the base of the live crown. 
The female bores directly into the cambium and constructs a nuptial chamber. 
Points of attack are characterized by the presence of distinct pitch tubes and fine 
reddish boring dust or white resinous boring particles in the bark crevices or on 
344 
