INSECT ENEMIES OF EASTERN FORESTS 561 
cocoons in the litter. Usually some larvae can be found until late in 
the fall, when cold weather stops their activity. The cocoons range 
in color from golden to dark brown and are about 24 inch in length. 
The winter is passed as prepupal larvae in the cocoons, and trans- 
formations to pupae and adults take place in the spring. 
In studying the natural enemies of this species, it was found that 
shrews, ground-feeding rodents, and predaceous beetles sometimes 
EUROPEAN SPRUCE SAWFLY 
DISTRIBUTION ---- 1938 
HEAVY 
MEDIUM 
LIGHT 
FicurRE 153.—Distribution in America of the European spruce sawfly in 1988. 
“Heavy” indicates severe defoliation, with most of the old and some of the 
new foliage eaten; ‘“medium,’’ noticeable feeding on old foliage; “light,” larvae 
present, but no noticeable defoliation. 
destroyed as high as 50 percent of the cocoons. Tremendous numbers 
of larvae may be killed by disease during the summer, particularly in 
the heavy infestations. In 1940 a larval disease was widespread and 
was responsible for reducing to a very low point the heavy infestations 
of southern New Hampshire and southern Vermont. The presence 
of the disease was noted in a number of localities in Maine in Septem- 
ber 1940, and very few living larvae were found at those points. On 
the other hand, a considerable number of the insects were in diapause 
in those areas, and whether the disease would carry over to larvae of 
subsequent generations was problematical. The exact nature of this 
sawfly disease is not known, nor has it yet been named. It has about 
the same effect as wilt diseases of other insect larvae. An infected 
larva rapidly loses its normal green color, changing first to yellowish 
green and then to black, and soon disintegrates. As the body content 
