LIBRARY

DIPTERA 781
breed in various kinds of fungi and especially in toadstools and mushrooms, and
some species are pests of the latter. The adults often appear in swarms in the
air and run rapidly over the foliage of plants and on the hosts.
The family is a very small one of some 100 described species which are most
numerous in the Holarctic region with representatives in oiher parts of the
world. According to Curran (1934) there are less than 30 described species in
North America. One of the most interesting species is the European smoke fly,
Microsania stigmaticalis Zetterstedt, which appears to be attracted in swarms
to smoke. It has been introduced into New Zealand and Tasmania.
The commonest genus is Platypeza Meigen. P. agarici Willard and P. polypori
Willard are common in toadstools and mushrooms in western North
America. The banner fly, P. insignis (Aldrich), is a common North American
species with long banner-like or foliate appendages on the hind tarsi of the male.
Family SYRPHIDlE (Leach 1815, 1819) (Syr'phi-dre, from the Greek au pcp os or
al:pcpos, a small winged insect, a kind of gnat or winged ant). German.
Schwebfliegen. Syrphid Flies, Flower Flies, Sweat Flies, Hover Flies,
Drone Flies.
Small, medium to large, smooth or pilose, common flies which are very active
on the wing, hovering and darting in the air with great agility. They are broad
or slender; somber and of one color or more often marked with bright-yellow,
orange. or creamy-white bars and spots; some are metallic blue, green, and
brassy. Head large, some with frontal projections. Antennre three-segmented
and may arise from small or large tubercles; with style or arista. Arista usually
dorsal, rarely dorsa-apical; simple or three-segmented; longer or shorter than the
apical segment; bare or plumose. Eyes usually dichoptic in females and haloptic
in males; naked or pilose. Proboscis normally short. rarely as long as the body
(in Lycastris cornutus Enderlein of Japan). Ocelli present. Thorax large, rarely
bristly. Legs normal. Wings large; apical cell closed; anal cell large, closed before
the margin; spurious vein (vena spuria), thought to be the vestigial M A.
lying between Rand M and free at both ends, is normally present and is one of
the most distinctive characteristics of the members of the family; it is only
rarely absent. Abdomen with fOUf or five visible segments. Male hypopygium
often large but not conspicuous. Eggs variable; some of the common ones
occurring among aphids are white, elongated and reticulated. Larvre variable.
II-segmented; amphipneustic and metapneustic, head reduced. The larvre
usually fall into one of the following four types:
1. Limpet or M icrodon - oval. convex; sculptured surface; hard or leathery;
with fused tubular anal spiracles and without anterior spiracles (metapneustic).
Represented by the genus Microdon Meigen living in ants' nests and feeding on
the dry pellets ejected by the ants.
2. Short-tailed or Syritta, cylindrical and robust; posterior respiratory tubes
short; with or without three pairs of fleshy protuberances on the last segment;
plumose hairs encircling the posterior spiracles. Represented by Syritta
St. Fargeau and Serville and Tropidia Meigen.