INSECT ENEMIES OF EASTERN FORESTS 621 
usually recognized in our fauna. Some of the species are of consid- 
erable economic importance because they are valuable parasites, some 
are hyperparasites, and a small number are inquilines. Compara- 
tively few species, however, are known to parasitize forest insects, 
and therefore only the two largest families and one small family are 
treated in the following discussion. 
Famity SCELIONIDAE 
This is a very large and widely distributed family. Its species are 
egg parasites, infesting the eggs of all orders of insects, those of forest 
insects being commonly attacked. — 
Many species of 7'elenomus have been reared from the eggs of forest 
insects, but comparatively little information exists regarding their 
life history. Eggs of Lambdina fiscellaria luqubrosa, the western 
hemlock looper, collected in the spring of 1930 in British Columbia 
by Hopping (237) and referred to as Hllopia somniaria, proved to be 
25 percent parasitized by a 7elenomus sp. Second-generation egg 
masses of the catalpa sphinx (Ceratomia catalpae), reared by 
Baerg (72) in Arkansas during 1928 and 1930, were heavily para- 
sitized by 7’elenomus catalpae Mues. 7’. clistocampae Ashm. is a para- 
site of the eggs of the eastern tent caterpillar (J/alacosoma amer- 
tcana) and the forest tent caterpillar (J/. disstria). The adults are 
tiny insects a little less than 1 mm. long, and dull black, except their 
legs, which are brownish. A small percentage of the eggs of the forest 
tent caterpillar in New England and the Great Lakes States are at- 
tacked by this species. The winter is spent as a larva within the host 
ego, and adult emergence is delayed until several weeks after hatching 
of the unparasitized eggs takes place. Adults, therefore, appear 
shortly before fresh egg masses are available. There is probably time 
for the development of two annual generations on this one host, but 
it is possible that there is only one generation. 
Famity PLATYGASTERIDAE 
This is the largest family of Serphoidea. Its species are principally 
parasites of Cecidomyiidae. Their eggs are usually laid within those 
of the host, but the development of the latter is not affected, because 
the parasites do not develop until the cecidomyiid larvae have hatched. 
A number of species have been reared from cecidomyiid galls found on 
various forest trees in this country, but apparently none of these species 
have been studied in any detail. 
Famity PELECINIDAE 
The Pelecinidae is an exceptional family in many ways. It is dis- 
tinct from the other families of the Serphoidea, and is represented in 
our fauna by only a single species, Pelecinus polyturator Drury and its 
subspecies P. brunneipes Patton. The female is a common North 
American insect, parasitic on May beetles of the genus Phyllophaga, 
but the male is extremely rare. The female is a large black insect 
often 2 or 21% inches long, with a long slender abdomen, which is 
about five times as long as the head and thorax. 
