INSECT ENEMIES OF EASTERN FORESTS ole 
considerable damage, the trees are not directly killed, but may be so 
weakened as to make them susceptible to the brood attacks of this or 
other boring insects. 
The peach bark beetle (Pithorophloeus liminaris), also known 
as the peach-tree bark beetle, attacks not only peach and other 
cultivated fruit trees, such as plum and cherry, but also breeds in 
wild cherry, wild plum, and mountain-ash. The fall brood of young 
adults emerge and hibernate in the bark of living peach, cherry, or 
plum trees, often causing a flow of gum. It occurs from New York 
and Michigan southward to Maryland and Tennessee. P. mississipi- 
ensis Blkm. and P. scabricollis Hopk. are closely allied forms and 
have similar hosts and habits. P. frontalis is widely distributed 
in the East, comparable to the range of its favorite host trees, the 
several species of mulberry. It is also said to breed in hackberry, but 
these records should perhaps refer to P. dentifrons. It is com- 
mon throughout the Southern States, where the black knots caused on 
living mulberry trees by the hibernating adults, and also the beautiful 
regular engravings on the wood of dead trees, are often seen. P. den- 
tifrons is found principally in the dying and broken limbs of hack- 
berry. It is probably rather widely distributed, as it is common 
in both eastern Kansas and northern Mississippi. Many of the young 
adults of the fall generation of this species remain in their burrows 
over winter, but it is possible that others may bore into the bark of 
living trees to hibernate. P. piceae differs from most of the genus in 
that it breeds in coniferous trees. It is common in white spruce in 
eastern Canada, in both white and red spruce in Maine. and in red 
spruce in northern New York. It often breeds in the rather dry bark 
of branches, as well as in fresher material, and is not destructive. The 
beetles of this genus have been discussed by Gossard (189), Blackman 
(38), and Chamberlin.”® 
The genus Vendroctonus Erichson contains a number of species 
more destructive to coniferous trees than any other group of insects. 
‘The most destructive species occur in the West, but at least two eastern 
species would probably be capable of comparable devastation if ch- 
matic and silvicultural conditions were equally favorable. Members 
of the genus are rather stout beetles, the species ranging in color from 
reddish brown to black, and in size from 2 to 9 mm. The eyes are 
oval, without emargination, and the antenna has a five-jointed funicle 
and a stout compact club, thickened at the base. Hopkins (234) pub- 
lished results of a special study of this genus. 
The southern pine beetle (Vendroctonus frontalis) is a native in- 
sect occurring from Pennsylvania southward to Florida and westward 
to eastern Texas and Oklahoma. It is the most serious insect enemy of 
pine within its range, as it attacks and kills healthy pines of practi- 
cally all species and practically all sizes except the smallest. A con- 
servative estimate of its damages in the Southern States since 1891, 
when it was first studied carefully, exceeds $50,000,000. 
In most years the southern pine beetle is difficult to find, but peri- 
odically it increases very rapidly under favorable climatic conditions, 
and an epidemic outbreak is soon under way. A number of such 
outbreaks have occurred during the last 50 years, the most recent of 
** See footnote 22, p. 302. 
