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766 COLLEGE ENTOMOLOGY
lough, hard, and plate-like, 12-segmented, exclusive of head; antennre distinct;
apodous; metapneustic or amphipneustic, some with one to three thoracic
spiracles and one to seven abdominal spiracles; aquatic or terrestrial; saprophagous
or predacious. Aquatic 1arvre feed on algre, decaying vegetation, or upon
aquatic animal life. Certain species have the terminal segment elongated into
a breathing tube furnished with a circular fringe of long hairs that spread out
on the surface of the water and support the suspended larvre. Some have also
been taken in hot and mineral springs. Terrestrial forms are saprophagous and
occur in mud, vegetable debris, dung, and rotting wood and fruit, and it is
thought that certain species are carnivorous upon other insect larvre feeding on
these substances. Eggs are laid in wet mud, water, refuse, dung, and in the soil.
The species are not known to be of economic importance to agriculture, but the
common Hermetia illucens (Linn.) has been associated with occasional cases of
intestinal myiasis.
The family comprises some 1,200 species which are widely distributed
throughout the world. The most important genera are Cyphomyia Wiedemann,
Hermetia Latr., Nemotelus Geoffroy, Odontomyia Meigen, Sargus Fab., and
Stratiomys Geoffroy. The species most often seen in collections belong to the
last named genus. Stratiomys maculosa Loew, a black and yellow species 14 mm.
long, is a common western species, and S. badia Walker is found in New England
and Canada.
Family TABANIDlE Leach 1819 (Ta-ban'i-dre, from the Latin tabanus, a
gadfly, horsefly). German, Bremsen. French, Taons. Horseflies, Green.
heads, Gadflies, Deerflies, Clegs, Breezes.
Medium-sized to large, robust, pubescent flies, usually somber colored and
with clear or clouded wings. Head large, hemispherical or somewhat triangular.
31' ' 2ndJl.+CUI'l
FIG, 276. Wing of the black horsefly, Tabanus alTalus Fab. Veins and cells named according
to the Comstock-Needham system. (After Bromley, 1926.)
Eyes large, contiguous or holoptic in some males or dioptic; naked or hairy,
often banded and with iridescent green, red, and other metallic colors. Ocelli
present or absent. Antennre long or short, porrect, with two well-defined basal