562 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
dries out the remains often adhere to the needle on which the larva 
was feeding when stricken. 
Thus far, native insect parasites have been unimportant as control 
factors in the United States and Canada, but in Europe a number of 
parasites are known to attack this species. Extensive programs have 
been carried on by the Canadian and the United States Governments 
in studying this insect and in importing, rearing, and colonizing its 
natural insect enemies. MMicroplectron fuscipennis (Zett.), a tiny 
wasplike insect which parasitizes this sawfly in the cocoon, was first 
introduced onto this continent by the Canadian Government. It is 
readily bred in the laboratory, and an average of about 25 individuals 
will develop i in a single sawfly cocoon. Many hundred millions of this 
species have been propagated by the Canadian Entomological Branch, 
the Bureau of Entomology and Plant Quarantine of the United States 
Department of Agriculture, and the States of Maine, New Hampshire, 
Vermont, and New York, and have been colonized throughout the 
infested areas. ‘The parasite has already become established in many 
localities, and appreciable percentages of parasitization have been 
found in some of the infested areas. 
One other species, Hxenterus marginatorius (¥.), a larval parasite, 
was also definitely established in Canada in 1939 and shows consid- 
erable promise in some localities. 
For control of Diprion hercyniae by spraying see pages 53 and 544. 
Famity CIMBICIDAE 
This small family, comprising three genera, includes only a few 
species. The adults of most species are large, the antennae are clavate 
or capitate, the abdomen is stout with the lateral margins sharply 
angulate, the mesosterno-pleural sutures are barely indicated by a 
slight ridge, the mesoscutellum is without a post-tergite but has the 
anterior mar gin V-shaped, the tibiae are without pre eapical spurs, and 
the apical spurs of the front tibiae are simple (Ross, 367). In the 
larva the head is large. The body is cylindrical, tapering toward 
the anal end, and in life it is covered with a waxy bloom. The larva 
is capable of ejecting a fluid from spiracular g elands when disturbed. 
Three species often attract attention in the Eastern States. 
The elm sawfly (Cimbex americana Leach), also called the giant 
American sawfly (fig. 154), is the largest of our American sawflies, 
the adults being robust and about 3/4, to Linch in length. The knobbed 
antennae and the tarsi are tinged with orange, and the w ings are 
smoky brown. The head and ‘thorax are black. The abdomen of 
the female is oval, usually steel-blue, and is marked with three or 
four yellowish spots on each side, but the abdomen of the male is 
longer, without spots on the sides (some specimens shaded to brown), 
and there is an oval whitish spot behind the thorax, which is hardly 
perceptible in the female. The larvae are yellowish white or greenish 
white, the spiracles are black, and each larva has a black stripe down 
the middle of the back. The skin is pebbled in texture, and each 
segment has many transverse wrinkles. When at rest the larvae are 
usually coiled, with one side of the body adhering to the underside 
of a leaf. Full-grown larvae are about 134 inches long. 
Cimbex americana is distributed throughout the northern part of 
the United States, westward into Colorado, and from southern Canada 
