about 43 mm long. While feeding, the larva usually coils its rear end around a stem 
or twig; at rest, it usually lies coiled like a snail (fig. 178). 
Courtesy Conn. Agric. Exp. Stn. 
Figure 178.—-Larva of elm sawlfly, 
Cimbex americana. 
Adults appear from about mid-May to mid-August, and the eggs are deposited in 
pockets cut into leaf tissues. Larvae occur from June until October, depending on 
location. When they become full grown, they crawl to the ground and spin tough, 
papery cocoons in the litter or just below the surface of the soil. Winter is spent in 
the prepupal stage, and pupation occurs in the spring. There is one generation per 
year. 
The elm sawfly is of minor importance as a defoliator of forest trees, but 
occasionally seriously defoliates shade tree elms. Willow also has been heavily 
attacked in th. Northern Great Plains area. The larvae partially or entirely defoliate 
the trees, while the adults chew the thin, tender bark of twigs, girdling and killing 
them (//52). 
Trichiosoma triangulum Kirby occurs quite commonly in the Eastern United 
States. The larvae are solitary feeders on the foliage of ash, birch, poplar, willow, 
and wild cherry. At maturity, they are 37 mm long. The head is creamy white, the 
body greenish white, and the eye spots and spiracles blackish. The life cycle is 
similar to that of the elm sawfly. 
Family Diprionidae 
Conifer Sawflies 
The family Diprionidae includes many of the most serious defoliators of coni- 
fers. The majority of species are native to the continent but several of foreign origin 
are well established. The family is divided into two subfamilies, Monocteninae and 
Diprioninae, and six genera (/099). Adults are described as follows: Antennae 
composed of 13 or more segments, serrate in the female, and pectinate or bipecti- 
nate in the male. Mesosterno-pleural sutures atrophied, mesoscutellum with ante- 
rior margin V-shaped, posterior margin with an extremely narrow and cordlike 
postergite (1/041). The larvae usually range in length from about 18 to 25 mm. The 
body is usually whitish, yellowish, or grayish with brown or black stripes or rows of 
more or less distinctly separated spots (1369). 
Many species of diprionids are serious pests in both forest stands and plantations. 
Outbreaks occur periodically, sometimes over extensive areas, resulting in loss of 
growth and sometimes tree mortality (29, 3/7, 238). 
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