fly is very similar to the housefly, especially the female, but her
eyes are closer together and her body is more rounded than in M.domestica.
The male has more orange on his abdomen. This is the fly that you see
swarming around cattle driving them mad, see above: This is also a fly
which likes to sunbathe on walls and fences. These flies also enter
houses and other buildings in autumn, just as the housefly population
is declining, and hibernate for the winter.
Face flies are most likely to invade farm homes or homes located near
pastures or where cattle are kept since the eggs are laid in cow pats
and the larvae develop there also. During the summer, the adults feed
on the mucous secretions from the eyes and noses of cattle and horses,
see biology below:
similar to the closely related house fly, ca. 1/4 to 5/16 inch long
and with a slightly darker body; sponging mouth-parts with microscopic
rasping "teeth"; face between eyes and mouth is silvery.
Domestic animals affected:
horses and cattle.
nuisance effect on animals, but research shows no direct reduction in
performance; they mechanically vector Moraxella bovis (pinkeye) bacteria
and are biological vectors of nematode eyeworms that affect cattle and
complete metamorphosis: egg, three larval instars (maggots), pupa, adult;
puparium is white, calcified.
Generational time: usually 12 to 20 days depending on
Oviposition site: fresh cow manure within hours after
Larval habitat, feeding:
larvae live in cow dung pats, feeding on the microbial flora and fauna
in it and on decomposition products resulting from microbial activity.
Adult habitat, feeding:
Off the host, they rest on vegetation or structures at night and most
of daylight hours or feed on plant sugars and juices on the surface
of manure deposits. On host animals, they obtain protein from nasal
mucus, saliva, and tears; microscopic "teeth" on their tongues
are used to abrade eye tissue to stimulate the flow of tears (see Note
below). Opportunistically, they are attracted to, and feed on, blood
made available by horse fly bites or other wounds. Face flies do not
enter dimly-lighted building interiors.
Method of dispersal or infestation:
Strong fliers capable of traveling several miles, but most stay within
the hosts vicinity; they do not come into buildings except for
the autumn (diapausing) brood which seeks an overwintering site.
Adults emerge from winter hibernacula in March and early April and may
be temporarily abundant on faces of cattle and horses at that time;
then they decline in number until June or July when the population rebounds;
present to numerous into mid-October.
Notes or comments: 70 to 95% of face flies on an animal
are females, as they need more protein than do the males.
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