The standard house fly (Musca domestica) annoys people but also serves as a transmission vector for bacterial infections, sometimes in ways that aren’t immediately obvious.
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Types of Flies
The house fly measures about a quarter-inch long and shows four distinctive stripes on its thorax, behind its head. But the house fly is just one of dozens of different kinds of flies that enter homes and food-preparation areas. These flying insects, sometimes called “filth flies,” are divided into two groups.
Fly Biology
House flies are only able to eat liquid foods. To eat solid foods, the fly must regurgitate saliva on the food and suck up what’s liquefied using the proboscis. Because house flies need to make a lot of saliva, they need water.
The little flecks that house flies leave behind are actually excrement. House flies can also deposit eggs on a variety of objects including yard waste, animal excrement, and garbage. The female fly lays about 150 eggs on a decaying food source.
The life cycle of a housefly usually lasts about three weeks. House flies live about 2.5 weeks in warm conditions but can live up to three months in the cold.
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How Flies Transmit Disease
Flies are born into a food source. House flies, for example, lay eggs in the garbage or animal droppings. The eggs hatch into maggots, eating the food around them. The maggots eventually turn into pupae, within which they affect their final transition into a winged adult fly.
After they’ve fully pupated, the mature flies continue their search for food. Their preferred food sources—generally, moist and decaying organic matter—naturally containbacteria, many of which are harmful to humans. When the fly eats, it regurgitates part of its stomach onto its new meal; the stomach acids digest the food, and then the fly drinks it up.
Because flies eat garbage, manure, and other bacteria-laden materials, and because they spit up their stomach contents on surfaces for which humans may make frequent contact, these winged devils are capable of transmitting more than 60 different serious illnesses, including:
Even if the fly didn’t eat on a surface that humans contact, the fly may have left droppings that contain these bacteria.
Controlling Fly Populations
Experts at Penn State’s Department of Entomology recommend four complementary approaches formanaging fly populations:
2 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Illinois Department of Public Health.House flies and other filth flies.Pennsylvania State University Extension.House flies.
2 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Illinois Department of Public Health.House flies and other filth flies.Pennsylvania State University Extension.House flies.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Illinois Department of Public Health.House flies and other filth flies.Pennsylvania State University Extension.House flies.
Illinois Department of Public Health.House flies and other filth flies.
Pennsylvania State University Extension.House flies.
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