

Everyone is familiar with house flies. They aren't the cleanest of

insects--they visit dumps, sewers, and garbage heaps. They feed on

fecal matter, discharges from wounds and sores, sputum, and all

sorts of moist, decaying matter like 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, including typhoid fever, dysentery, cholera,

poliomyelitis, yaws, anthrax, tularemia, leprosy, and tuberculosis.



Biology



People often confuse house flies with a lot of closely related

flies. House flies are easy to identify. They have four dark

longitudinal stripes on top of the thorax, or middle body region.

They vary in length from 1/8 to 1/4 of an inch.



The mouth parts of the house fly are adapted for sponging up

liquids. They cannot bite, but a similar-appearing stable fly can

bite. Flies ingest only liquid food. They feed on solid food by

regurgitating saliva onto it. The saliva liquifies the solid

material, which is then sponged up with the proboscis. They require

water since they continually salivate and void liquids. Fly specks

seen on surfaces visited by house flies are the excreted wastes.



Female house flies deposit their eggs in decaying matter such as

grass clippings, garbage, and human and animal excrement. Horse

manure is the preferred breeding medium. Each female deposits about

100-150 eggs on appropriate food. Eggs can hatch in 7 1/2 hours

when temperatures are high (about 99 degrees F), or it can take up

to 2 days in lower temperature.



Eggs hatch 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 find themselves.



Following three larval molts, mature larvae stop feeding and burrow

HOUSE FLIES
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 happen
in as little as one week, but typically it takes three weeks.

House flies normally live about 2 1/2  weeks during the summer, but
they can, at lower temperatures, survive up to 3 months. Some
overwinter outdoors in protected locations, or in crevices in
buildings. Flies normally stay within 1/2 mile to 2 miles from
their point of origin, but some have been known to travel as far as
20 miles to find food and a place to lay eggs.

Control

The four basic principles of house fly control are sanitation,
exclusion, non-chemical measures, and chemical methods. These are
listed in order of lasting effectiveness. 

Sanitation - Flies can't breed in large numbers if food sources are
limited. Don't allow materials such as manure, garbage, weed piles,
grass clippings, or other decaying organic matter to accumulate.
Keep trash cans clean and tightly covered. Be careful not to wash
garbage cans where the rinse water might drain into the soil; flies
can breed in soil full of organic matter. Dry out maggoty garbage
or dispose of it in fly-proof containers or landfills.

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 certain there are no openings at
the top or bottom. And check for openings around water or gas pipes
or electrical conduits that feed into the building. Caulk or plug
any openings. Ventilation holes can also serve as a route for flies
to enter a building. Ventilation is necessary to keep adequate air
circulation in a building, but use screening to exclude flies.

Non-chemical Measures - The use of devices like ultraviolet-light
traps, sticky fly traps, fly swatters, and baited fly traps can
eliminate many flies inside a home, but the fly swatter is an
economical control method for the occasional fly.

Chemical Control - If you have lots of flies inside your home, use
a space spray (aerosol) labeled for flying insects. Most space
sprays contain pyrethrins for quick knockdown, but aerosols give
only temporary relief. Find out why flies are there. Then take
steps to get rid of them through sanitation and exclusion methods.

Dewey M. Caron
University of Delaware 
Cooperative Extension Entomologist
9/90

Commercial companies or products are mentioned in this publication
solely for the purpose of providing specific information. Mention
of a company or product does not constitute a guarantee or warranty
of products by the Agricultural Experiment Station or Delaware
Cooperative Extension or an endorsement over products of other
companies not mentioned.
.
