ous 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 leaf-like 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 ab- 
normal growths. These may show up as swellings on the trunks 
of a badly infested tree. Infested trees are not killed, but they 
may be seriously weakened. 
Phloetribus frontalis Zimm. breeds in mulberry and is believed 
to occur wherever its host grows in 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 female constructs a short transverse egg gal- 
lery between the bark and wood, usually consisting of two short- 
branched tunnels extending in either direction from the entrance 
hole and deeply engraving the wood. The adults often cause seri- 
ous damage when they bore into the bark and feed on the phloem 
of living healthy trees. They tend to congregate in groups, and 
several groups may occur in a single tree. When patches of bark 
are killed they slough off. 
Phloetribus dentifrons (Blackman) occurs in the South and 
commonly in the Midwest. It breeds in hackberry. 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 over-wintering in their 
burrows often destroy the gallery patterns during their prolonged 
periods of feeding under the bark. 
The peach bark beetle, Phloeotribus liminaris (Harris), occurs 
in southern Canada and from New Hampshire to Michigan, Ten- 
nessee, and North Carolina in eastern United States. It is pri- 
marily a pest in peach orchards, but it also attacks elm, mul- 
berry, wild cherry, wild plum, and mountain-ash. Breeding is 
usually confined to weakened trees but the adults feed in the bark 
of living trees. Adults are light brown to nearly black, feebly 
shiny, sparsely clothed with long, whitish, fine hairs, and from 
1.5 to 2.2 mm. in length. The galleries and habits of the species 
are similar to those of P. frontalis, except that the galleries tend 
to be somewhat more irregular. Damage in peach orchards may 
be severe. In the forest, it is of minor importance. 
The genus Dendroctonus Erichson contains many 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-seg- 
mented; and the short antennal club is sutured toward the tip. 
Hopkins (368) and Wood (793) published important papers on 
the biology and taxonomy of the genus. 
The southern pine beetle, Dendroctonus frontalis (Zimm.), the 
most destructive of the eastern species of bark beetles, occurs 
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