A source for information on flies
has ever been to a picnic, BBQ or other outdoor gathering in Florida knows that they are inevitably going to
have to deal with that annoying guest (besides the drunk in-law) the fly. They are the first to show up and the
last to leave, and they always bring many, many friends. These winged party crashers are synonymous with
everything foul and disgusting, and the thought of one on your food is enough to turn your stomach. A fly
swatter only works for so long….
The house fly, Musca domestica Linnaeus, order Diptera, is one of the most common of all insects. The adult fly has
a distinct pair of frontal wings, with a hind pair that assists in balance. Although there are over 16,000 species
of flies in North America, the house fly is a ubiquitous Florida bug and can be found in almost any area humans
inhabit. It is worldwide in distribution and is a pest in
homes, barns, poultry houses, food processing plants, dairies, and recreation areas. It has a tremendous breeding
potential and during the warmer months can produce a generation in less than two weeks. In many areas of Florida
the house fly breeds continually throughout the year. There are quite a few species of blow flies and bottle flies
which are found in and around residences. The greenbottle, bluebottle, and bronzebottle flies are particularly
abundant in Florida. In urban areas these flies may be more abundant than house flies. Filter/moth flies (drain
flies), belong to the family of flies called moth flies. They are 1/16 to 1/18 in in length; light gray to tan in
color. Their life cycle is 7 to 20 days. Adult flies have the body and wings covered with dense, long hairs.
Moth/filter flies breed in decomposing organic material, such as moist plant litter, garbage, sewage, around
kitchen or bathroom sinks and water traps in plumbing fixtures.
The house fly is an extremely prolific breeder, and
during the warmer months it can produce a generation in
less than two weeks. In many areas of Florida the house fly breeds continually throughout the year. It has a
complete metamorphosis with distinct egg, larva or maggot, pupae and adult stages. House fly eggs are laid
in almost any type of warm organic matter, which makes animal manure, among other materials, a very common breeding
The eggs, which are laid in clusters of 75-100, hatch within 24 hours into tiny larvae or maggots. In 4-6 days the
larvae migrate to drier portions of the breeding ground and pupate. The pupae stage may vary in length, but in warm
weather it can take about three days. Warm summer conditions are optimal for its development, and it can complete
its life cycle in as little as seven to ten days. As many as 10 to 12 generations may occur annually in temperate
regions, while in tropical or subtropical regions more than 20 generations may occur!
Along with being a major nuisance, flies also pose a major health concern. Although this particular species doesn’t
bite, they can transmit pathogens such as viruses, bacteria, fungi, protozoa and nematodes. Pathogenic organisms
are picked up from garbage, sewage and other sources of filth, and then transferred on their mouthparts through
their regurgitation, feces and contaminated body parts to human and animal food.
The movement of flies from animal or human feces to food that will be eaten uncooked by humans is a particular
concern. Also, when consumed by flies, some pathogens can be harbored in the mouthparts or alimentary canal for
several days, and then be transmitted when flies defecate or regurgitate.
Several kinds of non-biting flies can be found in and around farms, residences, and food-handling
establishments. These flies can be harmful to health, causing annoyance and discomfort. All filth flies have an
egg, larva (maggot), pupa, and adult stage in their life cycle. The adult fly has 2 wings (the hind pair is reduced
to a knobbed balancing organ).
Filth flies are usually scavengers in nature and many are capable of transmitting diseases to
man. Filth flies can usually be grouped according to their habits and appearance as: houseflies and their
relatives; flesh flies, blow flies and bottle flies, filter flies, soldier flies, and vinegar (fruit)
In conditions where plumbing is poor or
lacking, such as outhouses or portable bathrooms, serious health problems can develop, especially if there are
outdoor food markets, hospitals, or slaughterhouses nearby. Among the pathogens commonly transmitted by house flies
are Salmonella, Shigella, Campylobacter, Escherichia, Enterococcus, Chlamydia, and many other species that can
cause serious illness. These flies are most commonly linked to outbreaks of diarrhea and shigellosis, but also are
implicated in transmission of food poisoning, typhoid fever, dysentery, tuberculosis, anthrax, ophthalmia, and
More than 100 pathogens are associated
with the house fly including: Salmonella, Staphylococcus, E. coli and Shigella.
These pathogens can cause disease in humans and animals, including: typhoid fever, cholera, bacillary dysentery,
hepatitis, ophthalmia, polio, tuberculosis and infantile diarrhea. Sanitation is critical to controlling these
pests, but accurate identification is essential for successful fly control. Here are some other things you should
know about flies and fly control:
- Depending on the species, the life expectancy of a fly is eight days to two months, or in some cases, up to
- Flies belong to the Order Diptera, meaning two wings. There are 16,000 species of flies in North
- Flies plague every part of the world except the polar ice caps.
- One pair of flies can produce more than 1 million offspring in as little as six to eight weeks.
- As many as 33 million microorganisms may flourish in a single fly’s gut, while a half-billion more swarm
over its body and legs.
- Flies spread diseases readily because they move quickly from rotting, disease-laden garbage to exposed
human foods and utensils.
- Because they only have two wings, flies land often and therefore can deposit thousands of bacteria each
time they land.
- U.S. Department of Agriculture sources reveal that flies contaminate or destroy $10 billion worth of
- For every fly seen, there are an estimated 19 more hidden from view. This means humans don’t even see most
of the flies present at an infestation.
Images and information derived in part
or in whole from Trueman's Scientific Guide to PMO 6th ED