Full-grown larvae are grayish green and from 18 to 25 mm long. The head, 
thoracic legs, and upper part of the anal plate are black and there is a longitudinal 
light stripe down the back. There are also two light-green stripes and one intense 
green or black stripe on each side. 
Winter is spent in the egg stage and hatching occurs from early April to mid- 
May. The larvae feed gregariously on the previous year’s foliage and devour all of 
these needles on one branch before moving to another one. New needles are never 
eaten. Larvae may also feed on the bark of new shoots. This may result in shoot 
deformation or death (/324). When the previous year’s foliage on a tree is com- 
pletely eaten before the larvae reach maturity, the tree is vacated and the larvae 
crawl to other trees to feed. Full-grown larvae either drop to the ground and spin 
tough, light to dark golden-brown cocoons in the duff, or they spin them in 
protected locations on the tree. Pupation occurs during late August or early 
September and the adults appear from early September to late fall. Eggs are laid in 
slits cut in the edges of current year’s needles in needle clusters near the end of a 
branch. From 6 to 8 eggs are usually laid in a single needle, and about 10 to 12 
needles in a single cluster are usually infested. There is one generation per year. 
Trees defoliated by the European pine sawfly are seldom killed, since the new 
foliage is never eaten and the tree is never entirely stripped of its foliage. Bark 
feeding may cause some twig mortality but it 1s not serious. Losses in height and 
diameter growth may be severe, especially following repeated defoliations. Damage 
is most severe to Scotch pines grown in Christmas tree plantations. 
During the late 1930's and early 1940's, colonies of the two European parasites, 
Dahlbominus fuscipennis (Zetterstedt) and another believed to be Exenterus abrup- 
torius (Thunberg), were received from Canada for release in eastern infestations of 
this sawfly. D. fuscipennis became established in New Jersey and within a few years 
became rather abundant locally (487). E. abruptorius also became established in 
New Jersey. So far, neither species has given adequate control. The European 
ichneumon, Lophyroplectus oblongopunctatus (= luteator) (Hartig) was released 
in Canada in 1962 and transferred to Wisconsin in 1979. It is established in both 
locations. A supply of a European polyhedrosis virus of the sawfly was also 
received from Canada for use in its control (//2, //3). It has proved to be very 
effective when applied as a spray either by aircraft or by knapsack or hydraulic 
sprayers (fig. 183). The literature on the biology, ecology, and control of the 
European pine sawfly has been reviewed (687, 76/). 
as 
F-519945 
Figure 183.—Colony of larvae of the European pine 
sawfly, Neodiprion sertifer. Larvae hanging head 
downward were killed by a polyhedrosis virus. 
392 
