forests from Newfoundland to Pennsylvania and west to Minnesota and Manitoba. 
White spruce appears to be the favored host; however, red, black, and Norway 
spruces also are attacked. Young larvae are yellowish green; older feeding larvae are 
darker green, marked with five longitudinal white lines, and about 20 mm long 
(fig. 188). The white lines are absent and the body is somewhat shortened in 
cocooned larvae. 
ee 
— 
nett. 
Courtesy Can. For. Serv., Gt. Lakes For. Res. Cent. 
Figure 188.—Larva of European spruce sawfly, Gilpinia 
hercyniae. 
In the Northeastern States there may be one or two generations per year or a 
partial third, depending on location. Farther north there is only one. In the 
Northeastern States, adults of the first generation appear from early May to June. 
Males are rare and reproduction is parthenogenetic. Eggs are laid in slits cut in old 
needles and hatching occurs within a few days. Larvae of all ages feed singly. 
Young larvae feed by chewing out small pieces of the needle or by eating all but the 
vascular bundle. Older ones consume the entire needle. Old needles are usually 
preferred, but full-grown new needles may be eaten also. Second-generation adults 
appear in early July or later and lay their eggs in needles. Hatching occurs shortly 
thereafter, and the larvae feed for 3 or 4 weeks. At maturity, they drop to the ground 
and spin cocoons in the litter in which they spend the winter. In the northern portion 
of the species’ range, some remain in diapause for several years before pupating 
(999). 
The European spruce sawfly found conditions favorable for a rapid increase in 
numbers once it gained a foothold in the spruce forests of North America. In 1932, 
serious infestations were found over an area of about 5,200 square kilometers of the 
Gaspé. Two years later evidence of defoliation was also apparent in Quebec, New 
Brunswick, and adjacent areas in the United States. By 1935, the Gaspé outbreak 
covered about 15,500 square kilometers, and tree mortality in some areas had 
reached serious proportions. Collapse of the outbreak by 1942 was caused by an 
accidentally introduced nuclear polyhedrosis virus disease (49). Since then popula- 
tions have fluctuated at very low levels, and the spruce sawfly is no longer 
considered to be an economic pest (9/3). 
During the 1930’s and 1940’s, the Canadian government imported and liberated 
approximately 20 species of parasites in infested areas (788). Substantial numbers 
of these parasites were also released in the United States. Two species of cocoon 
parasites and five species of larval parasites became established (328). 
397 
