INSECT ENEMIES OF EASTERN FORESTS 331 
Smaller trees are, however, sometimes more or less severely injured. 
Pruning and burning of the wilting twigs will aid in reducing the 
numbers of the beetle. 
Myeloborus ramiperda Sw. is about 2 mm. long. It breeds in the 
twigs of white pine. Itis rather widely distributed in eastern Canada, 
and in the United States from Maine to Michigan. J. fivazi Blkm. 
is larger (2.65 mm.) and is known only from two localities, one at 
Cranberry Lake in northern New York and a single specimen taken 
in Wisconsin. They breed in the leaf-bearing twigs of red pine. 
The genus Pityophthorus Eichh. contains more species than any 
other North American genus of bark beetles. There are numerous 
eastern species ranging from 1.3 to 2.75 mm. in length and in propor- 
tions from 2.6 to over 3 times as long as wide. Their color ranges from 
hght brown to black. The pronotum is asperate in front and margined 
behind, the elytral dechivity is more or less sulcate, and the front of the 
head in the female is often ornamented with longer or more abundant 
hairs than in the male. This genus and the preceding were discussed 
by Blackman (36, 38, 40) and by Swaine (407). 
Most of the species breed in twigs or small branches, but a few may 
also be found in larger material. All but a few live in the inner bark, 
but several species of the genus, such as Pityophthorus pulicarius, are 
pith borers and may also riddle the wood of the twigs, as does P. 
puberulus. The typical bark burrow is of the radiate type with from 
two to nine egg galleries, but a few species lay their eggs in a cave 
burrow. Most of the species are entirely secondary in that they attack 
limbs that are broken, cut, decadent, or dying from other causes. A 
few, however, are more aggressive and may attack and kill apparently 
healthy twigs. 
Most of the species of Pityophthorus breed in conifers, but a few 
are found only in deciduous trees. P. rhois breeds in several species 
of Rhus, including not only the ordinary sumac but also poison 
ivy. It occurs from Maine to Michigan and southward to South Caro- 
lina and Mississippi. A variety is found in witch-hazel and maple. 
P. natalis Blkm. has been taken from redbud in Mississippi and West 
Virginia. P. liguidambarus also occurs in Mississippi and West 
Virginia and breeds in red gum. P. erinalis occurs in various 
species of Rhus from Maryland to Florida. P. scriptor is common 
in sumac in Mississippi and ranges from Texas to Georgia and North 
Carolina. 
All the other eastern species live in coniferous trees. The various 
species of pine most frequently serve as hosts, but spruce, fir, and 
larch also are attacked by several kinds. A few species may be found 
in any one of these eastern conifers growing in the area in which they 
occur. Pityophthorus puberulus Lec. is common in eastern Canada 
and from Maine westward to Wisconsin and Kansas and southward 
to North Carolina. It has been taken from white, red, jack, and 
Virginia pines, red spruce, and balsam fir. In pine it is most com- 
monly found in the twigs of broken or cut limbs, but it occasionally 
attacks and kills living twigs, riddling the pith and wood as do the 
species of Myeloborus. P. opaculus Lec. occurs from Maine to South 
Dakota and south to West Virginia. It breeds in the twigs of all 
species of spruce in its range and is also found in white pine, larch, 
and balsam fir. P. pulicarius Zimm. is a widely distributed and ag- 
