Kurt Jones, Chaffee County Extension Director
County
Fair has come and gone, and one of the left-over benefits from County Fair is a
surge of house flies which descend upon our office. One of the contests that we “enjoy” is to see
who is better with the fly-swatter in our office. I typically suck at it, but I blame the
bifocals…
Several
species of flies commonly enter Colorado
homes. Most are merely nuisance pests.
Others are important because they can transmit diseases. House flies,
face flies and blow flies develop in manure and garbage and are commonly
contaminated with disease-causing bacteria, including those associated with
food poisoning.
The
most commonly observed stage of a fly is the winged, adult stage. The immature
stage is a pale, legless maggot. When full grown, maggots wander from the
breeding site in search of a place to pupate. Many flies complete development
(egg, larva, pupa, and adult) in a short period, seven to 14 days, and produce
many generations during a typical season.
Although
flies most often are a nuisance during the warm season, indoor overwintering is
common with cluster flies and face flies.
Blow
flies are fairly large, metallic green, gray, blue or black flies found
throughout the state. These flies tend to be more common than the house fly and
sometimes are called the "house flies of the West." The adults spend
the winter in homes or other protected sites but do not reproduce during this
time.
Blow
fly maggots feed on garbage. They occasionally can be found in homes that are
near a carcass of a dead squirrel, rodent or bird they have wandered from. Blow
flies breed most commonly on decayed carcasses and droppings of dogs or other
pets. The adult blow fly is also attracted to gas leaks.
House
flies are the best known of the house-infesting flies but are found
infrequently in Colorado. House flies generally are gray, with the thorax
marked with broad dark stripes. Most often there is some yellow coloring along
the sides, which differentiates them from face flies.
House
flies usually are found where humans are present. Larvae commonly develop in or
near man-made sources of food and can be found in garbage, animal waste, culled
fruits and vegetables, and spilled animal feed. The adult flies feed on a wide
range of liquid waste but can eat solid foods, such as sugar. To digest solid
foods, house flies liquefy food by regurgitating it. Because of this habit,
house flies can pose serious health threats by mechanically transmitting
disease organisms. During mild winters, house flies may fly and breed
continuously, as temperatures permit.
Sanitation
practices that remove breeding areas are fundamental to the control of
filth-breeding flies, such as house flies and blow flies. Remove or cover
garbage and clean spilled animal feed and manure. Face flies, which typically
develop in pasture lands, and cluster flies (earthworm parasites) often are
difficult to control by breeding area management.
Screening
and other exclusion techniques can be an important management tool for several
types of indoor fly problems. Caulk or cover all openings into a home to
prevent flies from entering. Do so
before flies enter buildings. Use
insecticides only as a supplement to other controls. Serious problems exist
with insecticide-resistant flies and many fly populations are now difficult to
control with insecticides.
If
I can get this fly to hold still, and figure out which lenses to look through,
I may have won today’s fly-swatting contest.
I think he’s laughing at me as he buzzes by…