Description:
House flies are 1/8- to ¼-inch long. They
are dull gray with four dark stripes on the back
of the thorax (segments right behind the head with
legs and wings attached). They have two wings; the
fourth longitudinal wing vein has a sharp upward
turn. The head is dominated by large red-brown compound
eyes which are surrounded by a light gold stripe.
Short antennae emerge from between the eyes. They
have sponging mouthparts. Mature housefly larvae
or maggots are spindle shaped and creamy white.
They have dark mouth hooks at the head end and breathing
slits that look like a “wavy W” at the
larger round tail end. House fly larvae are ¼-
to 3/8-inch long when they change to the brown seed-like
pupil stage.
Biology:
Female house flies lay their eggs singly but in
clusters of 75 to 150 eggs in a variety of moist,
rotting, fermenting, organic matter including
animal manure, accumulated grass clippings, garbage,
spilled animal feeds, and soil contaminated with
any of the above items. A female may lay more
than 500 eggs in a lifetime. The eggs hatch within
a day and the young larvae burrow into the breading
medium and complete development in three days
to several weeks depending on the temperature
and quality of food materials. Larvae migrate
to drier portions of the breeding medium to pupate
for three days to four weeks before emerging as
adults. Under optimum conditions, house flies
can complete their entire lifecycle in less than
seven days.
Habits:
The adult flies may migrate to uninfested areas
up to 20 miles away, but most stay within one
or two miles of the breeding site. Adult house
flies have a general appetite, feeding on foods
ranging from excrement to human food. They feed
on liquids but can eat some solid foods by liquefying
it with regurgitated digestive track fluids. During
the day, house flies rest less than five feet
above the ground and at the night they rest above
this height. House flies have been associated
with many filth-related diseases, and, thus, are
a significant health concern.
Control:
The initial inspection should focus on identification
of the fly(adult and/or larva) causing the problem
and location of all resting and larval development
sites. Because the adults after rest in breeding
areas, it is helpful to inspect at night. Sanitation,
or source reduction, is the most important step
in house fly control because it eliminates larval
breeding sites. When successful, it significantly
reduces the need for pesticide applications. If
trash cans are the problem, property owners should
be instructed to empty and clean them at least
weekly.
Mechanical control measures include insect-proof
garbage containers, self-closing doors, screening,
caulking and air curtains. Operating insect light
traps indoors and at night is effective in controlling
adult flies inside the structure. Sticky traps
and other devices are also available to reduce
adult fly populations indoors and out.
Any insecticide applications should be directed
at adults because sanitation and removal are the
best control measures for larva breeding sites.
Products used for fly control include baits, aerosols
and residual insecticides. The most widely used
pesticides are emulsifiable concentrates, wettable
powders and microencapsulated formulations. Most
residual applications are made to the daytime
and evening resting sites. Ultra-low volume and
aerosol applications should be made when the adults
are most active and there is the least risk of
drift, surface contamination, and human or animal
exposure.
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