several additional galleries during the season. Up to three generations may be 
produced annually. The first of these reaches maturity by midsummer and the 
second, by mid-September. The third brood spends the winter as larvae or young 
adults. 
The eastern larch beetle generally infests dying or injured trees. However, during 
the 1970's, thousands of apparently healthy tamarack were killed in the Adirondack 
and Green Mountains. In many stands almost all larches more than 10 cm d.b.h. 
were killed. Plantations of European larch at Wanakena, N.Y., also suffered losses. 
The lodgepole pine beetle, D. murrayanae Hopkins, is known from the Great 
Lakes region where it attacks stumps and the root collar of injured, windthrown, 
decadent or dying jack pine. Occasionally it infests red or eastern white pines. In 
the Rocky Mountain region of the West, this species has periodically been a serious 
killer of apparently vigorous lodgepole pine. Tree killing by D. murrayanae is often 
mistakenly attributed to the better known spruce beetle, which this species very 
closely resembles (/353). Like some spruce beetles, adults are distinctly bicolored, 
having reddish-brown elytra and black bodies. It is most easily differentiated from 
the spruce beetle by its host and by the habit of the larvae to continuously feed in 
contact with one another rather than construct isolated feeding tunnels. 
The Allegheny spruce beetle, D. punctatus LeConte, attacks stumps and the 
root-collar region of weakened or dying white and red spruces. This species is 
infrequently collected and apparently rare. It can be distinguished from the closely 
related D. rufipennis and D. murrayanae by its uniformly brown or dark-brown 
body covered with orangish, rather than pale-yellow, setae. Little is known about 
the biology of this species. 
The genus Phloeotribus is represented by a number of eastern species, all but one 
of which breed in deciduous trees. The adults are distinguished from other bark 
beetles by the loosely jointed antennal club, all three parts of which are extended on 
the inner side into a leaflike process. They breed in dead or cut material or in 
weakened or dying trees. Young adults burrow into the bark of living trees during 
the fall where they spend the winter. Their burrows often extend into the outer part 
of the living bark, causing irritations which result in abnormal growths. These may 
show up as swellings on the trunks of a badly infested tree. Trees that harbor 
overwintering aggregations are not killed, but they may be seriously weakened. 
Phloeotribus frontalis (Olivier) breeds in mulberry and is believed to occur 
wherever its host grows in the Eastern United States. Adults are brown and about 2 
mm long. The branches and trunks of living trees or the trunks and stumps of killed 
trees are preferred for breeding. The gallery system consists of two short and deeply 
engraved branches extending transversely from the entrance hole. Aggregations of 
adults overwintering in bark of healthy trees may kill patches of bark, which are 
later sloughed. 
Phloeotribus dentifrons (Blackman) breeds in hackberry in the South and in the 
Midwest. Adults are dark brown to black and 1.5 mm long. Injured or dying limbs 
are preferred as breeding material. Girdled or weakened trees or green logs are also 
attacked if the bark is fairly smooth and not too thick. Many of the adults of the fall 
generation spend the winter in their burrows. Others may emerge, then bore into the 
bark of living trees to hibernate. Adults overwintering in their burrows often 
obliterate the gallery patterns during their prolonged periods of feeding under the 
bark. 
The peach bark beetle, P. liminaris (Harris), occurs in southern Canada and 
from New Hampshire to Michigan and south to the Gulf Coast in the Eastern United 
350 
