INSECT ENEMIES OF EASTERN FORESTS Levi 
The injury caused by this aphid on spruce may be serious if the 
galls are numerous. Young trees may be killed, or growth may be so 
retarded as to invite attack by other destructive insects. On Douglas- 
fir, feeding by the aphid may cause an abnormal drop of foliage. 
Chermes lariciatus Patch attacks larch, also white and Norway 
spruces. It is closely related to the woolly larch aphid (C. strobilobius 
Kalt.) and the galls it produces on spruce closely resemble those caused 
by the eastern spruce gall aphid (C@. abietis). However, galls formed 
by this species have very short needles and are even more pineapple- 
shaped than those produced by C. abietis. This aphid causes little 
injury. 
Chermes strobilobius Kalt., the woolly larch aphid, an intro- 
duced European species, attacks larch as well as various species of 
spruce, principally red and black. On spruce it produces small galls at 
the end of the current growth. On larch it appears as white woolly 
masses on the needles, as dark individuals on the underside of twigs, 
and as clusters of dark individuals at the base of the leaves. It may be 
encountered from New England west to Wisconsin and south to Wash- 
ington , D. C. 
The fir bark louse, or balsam woolly aphid (Chermes piceae Ratz.), 
an introduced European insect, attacks various species of fir, princi- 
pally balsam fir, and is found in Nova Scotia, southern New Brunswick, 
New England, New York, and New Jersey. Infestations are charac- 
terized by white flocculence on the trunk and branches of balsam fir, 
a gouty, swollen condition of the tips of twigs, or as an abnormal 
growth of brittle, brown sapwood on the main trunks of trees. 
The fir bark louse overwinters in the nymphal stage in bark crevices, 
generally at the base of buds, on branches, or on the main stem. These 
nymphs resume growth in the spring when tree growth begins, and 
they rapidly develop into females, which deposit egg masses beneath 
the flocculent wax covering them, then die. Nymphs developing from 
these eges crawl about for a time before beginning to feed. Eventually 
they develop into another generation of females, which lay eggs and 
give rise to the nymphs that hibernate. 
The fir bark louse spreads chiefly in the crawler or nymphal stage, 
when the wind and air currents may aid in dissemination. Generally 
a single tree, or a small group of trees in a stand, is first infested. As 
the intensity of infestation increases there is a gradual spread to sur- 
rounding trees. All sizes of trees on any site may be attacked. A 
heavy infestation on the main stem may kill a tree in a single season, 
such trees being conspicuous because of red foliage. Large trees with 
gouty, swollen branches and twigs die slowly, but young stock bearing 
these swellings may die quickly. Injury has been particularly severe 
in localities in New Brunswick and eastern Maine. 
After a severe winter, only those nymphs that were protected below 
the snow line survived. According to Balch (76), a temperature of 
—30° F. is fatal to unprotected nymphs; however, it is probable that 
many die at even higher temperatures. Artificial-control measures 
consist of cutting and burning infested trees in isolated infestations 
and applying contact insecticides to infested ornamentals (pp. 52-54). 
Balch (76) and MacAloney (280) have published on this insect, 
