LIBRARY

DIPTERA 786
Syrphus arcuatus (Fallen) and S. ribesii (Linn.) (European and North American).
Volucella bombylans (Linn.) (European); V. esuricns (Fab.) (North
American).
The family comprises some 3,000 species.
Family PIPUNCULIDJE (Zetterstedt 18(2) Curtis, Walker 1851 (Pi/pun-cul/idre,
origin uncertain). Big-headed Flies.
Small, slender, somber flies with large, almost spherical heads and with
enormous contiguous eyes. The antennre may have the apical segment elon-
FIG. 290. The large syrphid fly. (From Insects of Western North America.)
gated and with a sharp apical style; long dorsal arista usually present. Ocelli
present. Proboscis small. Legs without spines; pulvilli present. Wings large
and with distinct veins. Females with exserted, chitinized ovipositor. The
larvre are small, pointed anteriorly, 10- to ll-segmented. Pupre in larval skin
with anterior spiracular horns and a pair of posterior spiracles. Pupation occurs
in the soil or litter. The adults visit flowers, grasses, and small shrubbery, and
may be seen hovering in the air. They are strong fliers and sufficiently skilled
to oviposit on the active nymphs chiefly of the homopterous families FUL­
GORID.t'E and CICADELLID.tE. The Iarvre are parasitic in the bodies of the
hosts and orient themselves so that the head is in the same direction as that of
the host. When mature they rupture either the dorsal or ventral integument
joining the thorax and abdomen, leaving a large hole in the carcass.
The family is a small but important beneficial one and includes some 300
described species which are chiefly Palrearctic. Considerable numbers of
representatives are found elsewhere, but extremely few are known from tropical
Africa and South America. The six common genera are Cephalasphrera Enderlein,
Chalarus Walker, Jassidaphaga End!., Nepheracerus Zett., Pipunculus
Latr. and Verrallia Mik. All except the first and third occur in North America.
The genus Pipunculus is the most widely distributed and contains most of the
known species, including many in Europe, about 35 in North America, t]3.ree
in Hawaii, four in New Zealand, and 26 in Australia. P. campestris Latr. is a