larvae eat only the outer, tender parts of needles; older ones con- 
sume the entire needle and nibble the bark. First generation 
cocoons are usually spun among the needles, at the bases of small 
branches, or in bark crevices on the trunk, and pupation occurs 
in late July. Second generation larvae feed until September and 
then spin cocoons on the tree or in the duff. Under favorable con- 
ditions some pupate and emerge in late fall to produce a partial 
third generation. The remainder do not pupate until the following 
spring. Because of some overlap between the first and second 
generations, all stages of the sawfly may be found during the 
summer (778, 520). 
Heavily infested trees may be completely defoliated in one 
season. When this happens late in the season after the buds are 
formed, many branches and occasionally trees may be killed. The 
introduced parasite, Monodontomerus dentipes (Dalm.), is occa- 
sionally very effective in control. Up to 75 percent parasitization 
has been recorded in New Jersey. Second generation larvae 
and cocoons located above the snow line on trees are particularly 
susceptible to low winter temperatures. 
Diprion frutetorum (Fab.) was discovered in North America 
in Massachusetts and Rhode Island in 1932, and now occurs 
throughout many of the Northeastern States and in southeastern 
| Whe 
COURTESY CONN. AGR. EXPT. STA. 
FIGURE 182.—Larvae of the ss. 
introduced pine sawfly, B\ Saw 
Diprion similis. , 
— 
451 
