INSECT ENEMIES OF EASTERN FORESTS 601 
Superramity JOHVNEUMONOIDEA 
Ichneumon Flies 
The superfamily Ichneumonoidea is the largest in the order Hy- 
menoptera, with the possible exception of the Chalcidoidea. About 
16,000 species have been described, but undoubtedly there are many 
times this number. All are parasites, preying on other insects or 
occasionally on other Arthropods. The group is of great economic 
importance, since most of the species are beneficial to man. The 
species exhibit great variety in shape and size and consequently are 
difficult to classify. The antennae are not elbowed, the pronotum 
extends back to the tegulae, the trochanters are two-jointed, the fore- 
wings possess a stigma, and the ovipositor issues in front of the apex 
of the abdomen. Ashmead (5) grouped them into 6 families and 
numerous subfamilies. A few representatives of the more important 
groups are briefly described in the following pages and, where prac- 
tical, parasites of forest insects are used as examples. It should be 
borne in mind, however, that the groups are too large and show too 
great a diversity of habit to be satisfactorily represented by the few 
examples which space permits in this publication; and, furthermore, 
the species chosen are rather outstanding examples and generally far 
more efficient than most of the parasites in the group. 
Famitry AULACIDAE 
The Aulacidae is a small family. Many of the species belonging 
to it are parasites of wood-boring coleopterous larvae, the Ceramby- 
cidae being particularly subject to attack. 
Famity ICHNEUMONIDAE 
The Ichneumonidae is a very large family and most of the species 
are medium-sized to large insects. Most of them are parasitic on 
Lepidoptera. Next in importance as hosts are the Hymenoptera, more 
especially the Tenthredinidae, but Coleoptera are frequently attacked, 
and all groups are preyed upon to some extent. 
The genus Amblyteles is one of the large genera, and many of the 
large, varicolored species emerge from pupae of forest insects. Ambly- 
teles sublatus (Cress.) is a common parasite of the saddled prominent 
(Heterocampa guttivitta) in the northeast, and A. velox (Cress.) is a 
parasite of the hemlock looper (Lambdina fiscellaria fiscellaria) in 
Ontario and Michigan. No comprehensive study has been made of a 
species of this genus which attacks forest insects in this country, but 
Kidmann (743) gave a good account of A. nigritarius (Grav.), an 
important parasite of the pine geometrid, Bupalus piniarius L., in 
Bavaria. The female of the parasite attacks the host larva. The 
parasite remains in an early larval instar until the host has pupated. 
It then develops to the last instar, overwintering in this stage and 
pupating the following spring. Transformation to an adult takes 
place within the host pupal shell through which the adult cuts a small 
opening in the anterior end, in order to emerge. Eidmann believes that 
the parasite probably completes a summer generation on some alternate 
host. 
