of Rhode Island GreenShare Factsheets
Musca domestica (Linn.)
Everyone is familiar with house flies. Common household
pests, they visit dumps, sewers and garbage heaps, feeding on
fecal matter, discharges from wounds and sores, sputum, and all
sorts of moist, decaying matter such as spoiled fish, eggs and
meat. Flies regurgitate and excrete wherever they come to rest
and thereby are ideally suited to mechanically transmit disease
organisms. House flies are suspected of transmitting at least
65 diseases to humans.
House flies are gray, approximately 6 mm (1/4 inch) long,
with four dark longitudinal stripes on top of the thorax, or
middle body region. The mouth parts of the house fly are adapted
for sponging up liquids. They cannot bite. Flies ingest only
liquid food; they feed on solid food by regurgitating saliva
onto it. The saliva liquefies the solid material, which is then
sponged up with the proboscis. They require water since they
continually salivate. Fly specks seen on surfaces visited by
house flies are the excreted wastes.
Female house flies deposit their eggs in decaying organic
matter such as garbage and human and animal excrement. Horse
manure is the preferred breeding medium. Each female deposits
about 100-150 eggs on appropriate food. Eggs hatch in a day or
two into worm-like creatures called maggots. Maggots lack definite
heads, eyes, antennae and legs. Their bodies are pointed at the
front end and gradually widen at the rear. Fly maggots feed on
the material in which they have hatched. Following three larval
molts, mature larvae stop feeding and burrow into drier surrounding
areas, where they pupate. The pupa is a chestnut-brown, oval
object within which the larva changes into an adult house fly.
Adults mate within one to two days after emerging from their
pupal cases. The life cycle from egg to adult can be completed
in as little as one week, but typically takes three weeks. House
fly adults normally live about two and a half weeks during the
summer, but they can survive up to three months at lower temperatures.
Some overwinter outdoors in protected locations, or in crevices
in buildings. Flies normally stay within one or two miles of
their point of origin, but some have been known to travel as
far as twenty miles.
The three basic principles of house fly control are sanitation,
exclusion and non-chemical measures. Sanitation will provide
the best long-term control, followed by exclusion and non-chemical
measures, which provide shorter-term management.
Sanitation: Flies can't breed in large numbers if
food sources are limited. Don't allow materials such as manure,
garbage or other decaying organic matter to accumulate. Keep
trash cans clean and tightly covered. If garbage becomes infested
with maggots, dispose of it immediately.
Exclusion: Flies can be kept outside of homes by
the use of window and door screens. Make sure screens are tight
fitting and without holes. Keep doors closed, making sure there
are no openings at the top or bottom. Check for openings around
water or gas pipes or electrical conduits that feed into the
building. Caulk or plug any openings. Ventilation holes should
be screened, as they can serve as entryways for flies as well.
Non-chemical Measures: The use of devices such as
ultraviolet-light traps, sticky fly traps, fly swatters, and
baited fly traps can eliminate many flies inside a home, but
the fly swatter is the most economical control method for the
Adapted from Dewey
M. Caron, University of Delaware, 1999
are poisonous! Read and follow all safety precautions on labels.
Handle carefully and store in original containers out of reach
of children, pets or livestock. Dispose of empty containers
immediately, in a safe manner and place. Pesticides should never
be stored with foods or in areas where people eat.
When trade names are used for identification, no product endorsement
is implied, nor is discrimination intended against similar materials.
Be sure that the pesticide you intend to use is registered for
the state of use.
The user of this information assumes all risk for personal injury
or property damage.
information, call the URI CE Gardening and Food Safety Hotline
at 1-800-448-1011 or (401)874-2929 from outside Rhode Island;
Monday-Thursday between 9 am and 2 pm.
of Rhode Island Cooperative Extension provides equal program