Black flies usually lay their eggs on grass and other materials 
just below the surface of water in swiftly flowing streams. The 
larval stage is spent in the water, usually attached to sticks, 
stones, or living vegetation. Adults are not strong fliers and are 
usually encountered in large numbers not too far from streams. 
Sometimes, however, the wind blows them a considerable distance. 
pone (694) published a list of species occurring in America north 
of Mexico. 
FAMILY BIBIONIDAE 
MARCH FLIES 
March flies are slender-bodied, stout-legged, rather hairy, and 
have short, many jointed antennae. They are usually dark colored, 
but may be marked with red or yellow. Full-grown larvae are 
distinguished by a fully developed false segment armed with 
spines behind the head. The common name, March flies, has been 
applied to the group because of the frequent appearance of the 
species, Bibio albipennis albipennis Say, in large numbers in 
March. The larvae usually feed on decaying vegetable matter, but 
a few feed on the roots of grass and other plants. 
FAMILY MYCETOPHILIDAE 
FUNGUS GNATS 
Fungus gnats are moderately small, slender, delicate, mosquito- 
like insects. The antennae have 12 to 17 segments, the wings are 
large, the coxae are prominent and elongated, and the tibiae are 
armed with spurs. The adults are often common in dark, humid 
habitats in wooded areas. Many species breed on mushrooms or 
on fungi growing on trees and logs. A number of others are pre- 
dacious and are found under bark or in the galleries of wood 
boring insects. 
FAMILY CECIDOMYIIDAE 
GALL MIDGES 
There are about 1200 species of Nearctic cecidomyids, of which 
several hundred are known to attack various trees and shrubs 
(256). The oaks are especially favored as hosts but several other 
species of trees are also infested, such as willow, elm, maple, wal- 
nut, and the pines. The larvae of about two-thirds of the Nearctic 
species cause the formation of galls or pronounced swellings by 
their feeding (241). Others feed in such places as patches of pitch 
exuding from injured limbs, in the excrement of insects, birds, 
and mammals, and in galls produced by other insects. A few are 
predators on small insects such as asphids, mites, psyllids, and 
scales. 
Gall midges are small, mosquitolike flies with relatively long 
antennae and legs. Young larvae are slender, somewhat flattened, 
and taper toward each end. Full-grown larvae are distinguished 
A417 
