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Photo
Credit: Tom Myers
AT A GLANCE:
Size: 1/8-inch
Color: Tan
Top of Prothorax: No markings
Other Identifying Characters:
Red eyes
ID Tips.
Fruit flies are small, tan-colored flies about 1/8-inch in
length including the wings. A key identifying character is its
bright red eyes.
Basic Biology. The fruit flies comprise several different
species belonging to the genus Drosophila and may also be
known as pomace flies or vinegar flies. The latter nickname
stems from the fact that this fly is common in facilities which
produce vinegar.
The fruit fly breeds in and feeds on
ripened fruit and vegetables and moist, decaying organic matter.
Because it frequents such unsanitary areas, it could potentially
carry disease-causing bacteria onto food products. Fruit fly
larvae living in fruit which is eaten can cause intestinal
discomfort and diarrhea. For this reason, health professionals
and sanitarians are concerned when these flies are found
infesting facilities where food is prepared, processed, or
served.
Like all flies, fruit flies
develop by complete metamorphosis. The tiny eggs are deposited
near the surface of fermenting fruit or organic matter. The
larvae emerge from the eggs and feed near the surface of the
fermenting material for 5-6 days. The larvae then crawl to drier
areas of the food source or even out of the food source to
pupate. Under ideal conditions, the life cycle from egg to adult
can be completed in as little as eight days.
Key Inspection Tips. When fruit flies have been
identified as the infesting pest fly in a building, the key to
control is to find all the breeding sources and remove them.
This is many times easier said than done. When searching for the
breeding sources of fruit flies, keep in mind that the larvae
can survive only in decaying or fermenting organic matter which
is moist. An obvious source to check would be fruits or
vegetables which are stored outside of a refrigerator or cooler.
One piece of rotting produce in a box of oranges, bananas, or
potatoes could breed hundreds of flies. A piece of fruit or a
vegetable can also be dropped onto the floor and be kicked under
a table or stove and serve as the source for hundreds of flies.
A second common fruit fly source
is trash containers which are not cleaned regularly. Inspect
trash containers by lifting the bag, if one is present, and look
for moist debris which could serve as a breeding source. Look
for fly larvae in the debris and adult flies inside the
container. It is sometimes necessary to poke through decaying
organic debris to uncover fly larvae.
Fruit flies may also breed in any
moist, decaying organic matter trapped in cracks of kitchen
equipment or under the bottom of such equipment where it meets
the floor. To determine if flies are breeding below the bottom
of equipment, use a knife or small spatula to scrape any debris
from inside the crack. If live fly larvae are found in this
debris, the crack is serving as a breeding site. It may be
necessary to check all cracks at floor level in this manner.
Fruit flies will also breed in
discarded fruit juice and soft drink cans, inside unsecured
bottles of wine or other beverages, in dirty mop heads and broom
bristles which stay wet or moist inside closets. Fruit flies are
less commonly found in drains than other flies, such as the
phorid fly or moth fly. Fly larvae live in the moist film that
develops on the sides of a drain and in debris which may become
trapped at the top of the drain.
Don't stop looking when one breeding
source has been found. In most cases, several breeding sources
will be present.
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