Adults emerging from elms dying from Dutch elm disease often carry spores of 
the disease-causing fungus on their bodies. When they bore into the bark of healthy 
elms to feed or hibernate, some of the spores rub off onto the walls of their tunnels, 
inoculating the tree with the disease. In most of the United States, the native elm 
bark beetle has been displaced by the more aggressive smaller European elm bark 
beetle. In northern New York, New England, and Canada, where the latter species 
is limited by low winter temperatures, the native elm bark beetle is the primary 
vector of Dutch elm disease. 
The genus Dendroctonus contains some of the most destructive insects affecting 
conifers in North America. The adults are reddish brown to black and from 2 to 9 
mm in length. The body is cylindrical and rather stout; the head is broadly rounded 
and visible from above; the antennal funicle is five-segmented; and the short 
antennal club is sutured toward the tip. Important papers on the biology and 
taxonomy of the genus are available (59/, 1353). 
The southern pine beetle, D. frontalis (Zimmermann), the most destructive of 
the eastern species of bark beetles, occurs throughout the Southeastern and South- 
ern States. From 1948 to 1975 more than 14 million cubic meters of pine timber 
were killed during a series of outbreaks in the Southern States (fig. 159). The insect 
also occurs in Mexico, Guatemala, and Honduras. During a catastrophic outbreak 
in Honduras in the early 1960’s, more than 55 million cubic meters of pine were 
killed. It breeds in all species of yellow pines in its range; also in eastern white, red, 
and spruce pines, and red and Norway spruce. Shortleaf, loblolly, Virginia, and 
pitch pines are the most highly favored among the yellow pines. Infestations in 
slash, longleaf, and eastern white pines are usually unsuccessful because of heavy 
resin exudations. Attacks on red spruce are also unsuccessful, the beetles dying in 
them after constructing short tunnels (692). 
Figure 159.—Deteriorated loblolly pines 5 years after 
they were killed by the southern pine beetle, 
Dendroctonus frontalis. 
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