INSECT ENEMIES OF EASTERN FORESTS 631 
Where wasps nests are built in inaccessible places, as in walls, the various 
entrances of the wasps should be noted. At night the openings are plugged, with 
the exception of the main one. Through this opening benzol or carbon tetra- 
chloride is sprayed, and it is then tightly plugged. 
Yellow-jacket nests in the ground may be destroyed by pouring about a tea- 
cupful of carbon tetrachloride or carbon disulfide in the hole and covering it 
with earth or wet sacks. This should be done at night when the wasps are all 
in the nest. 
Open lights, lighted cigarettes, etc., should not be brought around if carbon 
disulfide is used, because the vapor of this chemical is explosive. 
Fly sprays, if applied with a compressed-air or bucket sprayer sometimes can 
be used to advantage in cleaning out wasp nests. If the nest is kept well enveloped 
in a droplet spray, the wasps have little chance to escape or to sting the operator. 
Downes (140) reported that excellent control could be obtained with 
derris powder (4 percent rotenone). In treating wasp nests built in 
the wall of a building, throw a handful of derris in the crack through 
which the wasps emerge, and if it can be made to lodge where the wasps 
will get it on their bodies, as they pass through, the insects will usually 
be exterminated in 24 hours. It may sometimes be necesssary to block 
all entrances except one. Hornets and yellow jackets may also be 
killed within the nest by throwing in derris powder. <A valuable aid 
in obtaining good distribution of the dust is the use of an applicator 
consisting of a bulb (8-ounce) having a cone-shaped metal nozzle. The 
dust is effective as long as it is dry. 
Famity PSAMMOCHARIDAE 
The family Psammocharidae is mentioned because it is an extensive 
group, many species of which are commonly encountered. These in- 
sects are remarkable for their extreme activity and ability to run. 
Most all are predatory, and their prey consists almost exclusively of 
spiders. 
SuperramMity SPHECOIDEA 
The superfamily Sphecoidea includes the Ampulicidae, which prey 
on cockroaches, the Dryinidae, which parasitize nymphs of Homoptera, 
and the Sphecidae, which include all of our common nest-building 
sphecoid wasps. The pronotum does not extend back to the tegulae, 
except in some Dryinidae and Ampulicidae, the trochanters are single- 
jointed, the hind tarsi are not dilated, and the pubescence of the head 
and thorax is simple, not plumose. The Sphecoidea are relatively 
unimportant as forest insects, and therefore they are treated very 
briefly. 
FamMity DRYINIDAE 
The members of the Dryinidae are all parasitic on nymphs of 
Homoptera, and especially on those of the families Membracidae, 
Jassidae, Fulgoridae, and Cercopidae. Their biology is exceptionally 
interesting. During the larval stages they are internal parasites in 
the abdomen of the host, and usually one or several external gall-like 
cysts develop on the integument of the attacked insect. These cysts 
contain the parasite larvae. Many of the cysts are as large as the 
abdomen of the host. Pupation takes place either on the food plant 
of the homopteron or in the soil. Aphelopus theliae Gahan is a para- 
site of the membracid Z’helia bimaculata F., which feeds on young 
