INSECT ENEMIES OF EASTERN FORESTS 533 
phaeorrhoea Don.) 3; and Sturmia scutellata (R. D.), parasite of the 
gypsy moth (Porthetria dispar L.). Chaetevorista was liberated in 
Massachusetts in 1929-30 and during the years that followed up to 
1936 it showed ever-increasing effectiveness. In 1936 many of the 
parasites were winter killed and parasitization dropped considerably. 
Recent observations, however, indicate that it is again on an upward 
trend. Both species of Sturmia are well established in New England 
and are effective enemies of their host species. 
= Famity BOMBYLIIDAE 
Bee Flies 
The Bombylhidae, or bee flies, are delicately haired flies, rarely with 
conspicuous bristles, and often with pictured wings. The bombylids 
are among the first flies to appear in the spring. Their flight is swift 
but broken by abrupt pauses. The habits of the larvae, w hich resemble 
the asilids, are diverse. Some of the species live in the nests of vari- 
ous Hymenoptera, others are parasites of Lepidoptera and of white 
grubs or hyperparasites in Hymenoptera and certain tachinids, and 
others are predatory on locust eggs. 
PREDACEOUS DIPTERA 
A considerable number of species of Diptera have been reported as 
predaceous on forest insects. The larvae of such species may be found 
under the bark in the burrows of wood-boring insects, in tree pockets, 
or in dying or decayed wood. Many others are soil inhabiting. Since 
some scavenging or fungivorous Diptera occupy the same habitat as 
the predaceous species, ‘confusion of identity will result unless the 
observer is assured of the habits of the species under study. 
KEY TO FAMILIES 
LARVAE 
18: Niandiblesscickie=sivaje diye ses =e = co a ee ee eee ee 2 
Mandibles;shertiandshooklike. === 2222222 025s Syrphidae, p. 539, 
Lonchaeidae, p. 536 
2: Posterior spiracles approximated; body wholly or in a part longi- 
ts nol titaveal lily ams (oTeded Ge Cline ert ee ree eR eccrine cna re a Ses eee 3 
Posterior spiracjes separated; body not shagreened, reticulated, or 
SEEDED A es es le ea eM es ee LP Se Sea 4 
3. Head retractile; body usually longitudinally striated; posterior 
spiracles in a vertical depression; pupa free 
Tabanidae, p. 529. 
Head not retractile; body finely reticulated; pupa enclosed in 
Varaallaskermmes see ewe ee. See ee Stratiomy lidae, p. 539. 
4. Head more or less retractile, not cone-shaped_________________-- 5 
Head heavily chitinized, cone-shaped, not retractile__Xylophaginae, 
p. 536. 
5. Posterior spiracles situated upon the apical segment_____________ 6 
Posterior spiracles situated upon the penultimate or antepenulti- 
TOMER GOES TINE TN by Uy gee me pt lg pa eg Se el a Poneto ee ea a 8 
6. Apical segment ending in 2 long processes which are fringed with 
IR TNS emeemra pam aertilee eh aE We, PVE S yey Bis ey Rhagionidae, p. 536: 
MpicalesecimentmnOotsas abOVves sacs aU ee ee ee se ee ad 7 
ts Apical abdominal segment ending in 4 short pointed processes or 
lips; internal portion of head with a large arched chitinized 
ONE RSs ges tae eed i Spee mee a Se a Rhagionidae, p. 536 
Apical abdominal segment not as above or the internal portion of 
head is without arched upper plate; apical abdominal segment 
frequently with projecting processes; spiracles large 
Dolichopodidae, p. 535, Empididae, p. 535. 
