Canada. Its favored hosts are red and Scotch pines, but it may 
also attack various other hard pines. Full-grown larvae are light 
green with reddish brown heads and are about 20 mm. long. The 
body is marked with six longitudinal dark green stripes, two on 
the dorsum and two on each side (fig. 183). 
Winter is spent as a full-grown, cocooned larva and pupation 
occurs in the spring. Adults appear from late May to late July. 
Eggs are laid in slits cut in the needles. The larvae feed singly, 
preferably on the older needles. Because of their greenish color 
they blend into the background and are difficult to see. Usually, 
the first sign of infestation is the presence of frass and green 
needle fragments on the ground beneath the tree. Heavy infesta- 
tions occur occasionally in pine plantations (637). 
The European spruce sawfly, Diprion hercyniae Hartig, was first 
recorded in North America near Ottawa, Canada, in 1922. In 
1929 it was found in the United States on Mount Washington, 
New Hampshire. By the late thirties it had spread throughout 
the eastern spruce forests. White spruce appears to be the 
favored host; however, red, black, and Norway spruces also are 
attacked. Young larvae are yellowish-green; older larvae are 
darker green, marked with five longitudinal white lines, and 
about 20 mm. long (fig. 184). During the last instar, the white 
lines are absent and the body is somewhat shortened. 
In the Northeastern States there may be 1 or 2 or a partial 
third generations per year, depending on location. Farther north 
there is only one. In the Northeastern States, adults of the first 
generation appear from early May to early June. 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 
F-519578 
FIGURE 183.—Larvae of 
Diprion frutetorum. 
F-519573 
FIGURE 184.—Larva of European 
spruce sawfly, Diprion hercyniae. 
452 
