INSECT ENEMIES OF EASTERN FORESTS 559 
the larva molts into the last instar it loses the darker markings, except 
for the eye spots. The larvae prefer red pine and Scotch pine. There 
is one and at least a partial second generation each year in New Eng- 
land. The winter is passed in the cocoon stage, and the adults from 
this generation may emerge from the latter half of May to the last 
of July. Those of the next generation may emerge from the latter 
part of July to the first part of September, or may remain as prepupae 
in the cocoons until the next spring or later. 
Eges are deposited singly in slits in the foliage. The larvae of 
the first generation may ‘be found from about June 1 to early in 
August, and those of the second generation from late in July until 
late in the fall. They are solitary in habits and their color blends 
with that of the pine foliage. Some of the cocoons are spun on the 
C 
FIGurRE 151.—Diprion hercyniae: Fifth-instar larva, cocoons, and adult female. 
pine twigs, but by far the larger number are formed in the duff near 
the base of the host tree. 
This species is an introduction from Europe and, although not 
abundant enough to attract much attention, it apparently has been 
established in North America for many years, because it is now known 
to occur in Connecticut, Massachusetts, New Hampshire, New Jersey, 
New York, Pennsylvania, Rhode Island, and in a few localities in 
Ontario, Canada. The population, however, has been increasing in 
a number of forest plantations in some of the Northeastern States 
during the last few years, and in some localities in Connecticut the 
feeding has been heavy. The presence of excrement and green-needle 
fragments in the litter on the ground may be the first evidence of a 
heavy infestation. 
The young larva of the European spruce sawfly (Diprion her- 
cyniae (Htg.)) is yellowish green, but when nearly full grown (about 
4- inch in length) it is darker oreen, with five narrow longitudinal 
white lines. When the larva becomes full-fed and molts into the last 
instar the white lines disappear and the body shortens somewhat. 
The larvae drop to the ground to spin their cocoons (fig. 152) 
Diprion hercyniae is a native of Europe and was first found in 
Canada in 1922 near Ottawa, and in the United States in 1929 on 
Mount Washington, N.H. It did not attract attention, however, until 
1930, when it caused serious defoliation of spruce on the Gaspe Penin- 
sula, Canada. It is now apparently well distributed through the 
Provinces of Quebec, New Brunswick, and Ontario, Canada, and in 
the United States throughout New England, New York, and New 
Jersey. This wade range » indicates that it had been on this continent 
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