92 MISC. PUBLICATION 273, U. 8S. DEPT. OF AGRICULTURE 
SAWFLIES ON BROADLEAVED TREES 
There are a large number of sawflies that feed on the leaves of 
broadleaved trees. Some of these produce galls, and many others 
feed externally on the leaves and cause a varying amount of damage. | 
Only a few will be mentioned here. 
The elm sawfly (Cimbex americana Leach) is commonly found in 
the Middle West as well as in the Eastern States, but ranges west 
into Colorado and British Columbia. These sawflies are active feeders 
on the leaves of willow and elm, and also attack poplar, alder, maple, 
and other trees. The adults are large, steel blue to black, broad- 
waisted sawflies about three-fourths of an inch in length with three 
or four yellow, oval spots on each side of the body, short knobbed 
antennae, and smoky wings. They girdle the bark on twigs and kill 
many of them, especially in the tops of trees. The larvae are naked, 
wrinkled, and pale yellowish with a median black stripe down the 
back, and have eight pairs of prolegs. They usually he coiled and are 
from 1 to 2 inches long when full grown. The adults fiy in May 
and insert their oval eggs in the leaves. The larvae reach full 
growth in July or August, and overwinter 1n cocoons in the debris on 
the ground or just below the surface. Pupation occurs in the spring, 
only a few days before emergence and flight. 
At least three other sawflies attack willow in the West. Cimbex 
pacifica Cress., which has similar habits to the preceding, is found 
in Oregon and Washington, where the larvae feed on willow leaves. 
The adults are large, about 1 inch in length, and are brownish red. 
It is known as the Pacific sawfly. Cimbea rubida Cress. is found 
in the sierras of California and Nevada and along the coast, feed- | 
ing on various species of willow. The adults are about three-fourths | 
of an inch in length, reddish brown, with black stripes on the abdo- 
men and wings of metallic blue or smoky brown. Another species, 
Lrichiosoma lanuginosa Norton, also feeds on willow in the Cali- 
fornia and Nevada sierras. The adults, which are velvety or shiny 
bluish black, with dense pale-yellow hairs on head, thorax, and base 
of abdomen, look very much lke large bumblebees. They are about 
three-eighths of an inch in length and have short knobbed antennae 
and smoky brown wings. 
The cottonwood sawfly (Pteronidea sp.) although common, has 
not been identified specifically as yet. The larvae, which are slender, 
about one-half inch in length, green, with brown head and black 
eyes, and six pairs of prolegs on the abdomen, feed on the leaves 
of black cottonwood in northern Idaho. During the early feeding 
period the larvae skeletonize the leaves, eating only the fleshy part, 
but in the later stages of larval development the entire leaf is con- 
sumed. When mature the larvae construct small, parchmentlike 
cocoons that are attached to the leaves. The complete seasonal his- 
tory of this insect has not been determined, but it appears to have 
one generation a year. 
LEAF BEETLES 
There are a number of beetles that are leaf eaters in the larval 
or adult stage or in both. None of these have been responsible for 
any noticeable injury to western coniferous forest trees, but the 
skeletonizing and defoliation of broadleaved trees by beetles is a 
