How Long Do Flies Live? The House Fly Life Cycle by Temperature
An adult house fly usually lives 15 to 25 days and can live up to two months, but only about two to three days without food. Temperature sets the pace: in a North Carolina State laboratory study, half of female house flies were dead after about 43 days at 68°F but after only 10 days at 95°F. The full cycle from egg to adult takes as little as 7 to 10 days in summer and up to two months in cool weather. Fruit flies and drain flies follow similar short cycles, which is why removing the breeding source works better than swatting adults.
Most people asking how long flies live want to know one of two things: whether the fly buzzing around the kitchen will die soon on its own, or why killing flies never seems to reduce their numbers. Both answers come from the same numbers, and they are set out below with the source for each.
How long common flies live
“Fly” covers several unrelated insects in a house. Their life spans differ, but every one of them breeds faster than a single adult dies.
| Fly | Egg to adult | Adult life span | Eggs per female |
|---|---|---|---|
| House fly | As little as 7 to 10 days in summer; up to 2 months in poor conditions | Usually 15 to 25 days, up to 2 months; 2 to 3 days without food | Up to 500 (field guidance); 184 to 729 in a laboratory study, depending on temperature |
| Fruit fly | About a week; 1 to 2 weeks depending on temperature | Laboratory median about 80 days on an ideal diet, maximum about 100 | About 500 (Kentucky) to as many as 2,000 (New Hampshire) |
| Drain fly (moth fly) | 8 to 24 days, depending on temperature and humidity | About 2 weeks with fluids; 3 to 4 days without | 30 to 100 |
| Green bottle fly (a blow fly) | About 11 days at 81°F, adding the published stage times | Not given in the extension sources we read | Clusters of up to 200 at a time |
| Mayfly (not a true fly) | Typically a year, almost all of it underwater | One or two nights | Not relevant indoors |
Sources: University of Florida (house fly, green bottle fly), Fletcher, Axtell and Stinner 1990 (laboratory house fly data), University of Kentucky and University of New Hampshire (fruit fly), Piper and Partridge 2016 (laboratory fruit fly life span), Alabama Cooperative Extension (drain fly), Texas A&M (mayfly).
Read the fruit fly life span with care. That 80 day median comes from flies kept in laboratory vials on a controlled sugar and yeast diet, a best case. It shows how long the species can live, not how long a fly in your kitchen will.
How long do house flies live?
University of Florida’s fact sheet puts it plainly: adults usually live 15 to 25 days but may live up to two months. Three things decide where a particular fly lands in that range.
- Food, especially sugar. Florida notes that longevity is enhanced by suitable food, especially sugar, and that access to manure does not lengthen adult life.
- Temperature. House flies live longer at cooler temperatures. A warm summer fly lives fast and dies young.
- Protein, for egg laying. Females need protein to produce eggs, and Florida says manure alone is not adequate, which is one reason kitchens, bins and pet food attract them.
House fly life span by temperature
The clearest data come from a North Carolina State University study that kept adult house flies at constant temperatures and recorded when they died. It reported mortality as a rate; we converted each rate into the number of days until half the flies had died.
| Temperature | Days until half the females died | Days until half the males died | Eggs laid per female |
|---|---|---|---|
| 68°F (20°C) | 43 | 34 | 184 |
| 77°F (25°C) | 24 | 21 | 729 |
| 86°F (30°C) | 17 | 15 | 709 |
| 95°F (35°C) | 10 | 12 | 506 |
Two things stand out. A fly at a cool 68°F lives about four times as long as one at 95°F. And egg output peaks in the mid 70s to mid 80s, at 709 to 729 eggs per female, higher than the commonly quoted figure of 500. Florida’s fact sheet agrees that maximum egg production occurs at intermediate temperatures, 77 to 86°F. A comfortable kitchen in summer is close to ideal for house flies.
The house fly life cycle, stage by stage
A house fly passes through egg, maggot, pupa and adult. UC IPM gives as little as 7 days from egg to adult under ideal summer conditions, and the University of Florida 7 to 10 days.
| Stage | Warm weather | Cool weather |
|---|---|---|
| Egg (about 1.2 mm) | Hatches in 8 to 20 hours | Not given; eggs must stay moist to hatch |
| Maggot (grows to 7 to 12 mm) | 4 to 13 days at optimal temperatures | 14 to 30 days at 54 to 63°F |
| Pupa (about 8 mm) | 2 to 6 days at 90 to 99°F | 17 to 27 days near 57°F |
| Adult | Usually 15 to 25 days | Lives longer; up to 2 months |
Florida’s figures put the whole cycle at 7 to 10 days in summer and up to two months under poor conditions, with 10 to 12 generations a year in temperate regions and more than 20 in the subtropics and tropics. In cold climates house flies spend the winter as larvae or pupae in protected places, not as long-lived adults.
The maggot stage is where flies are most vulnerable to you. Our guide to maggots in the trash can shows how one weekly collection cycle lines up with one summer generation.
How long do flies live indoors?
Indoors, a house fly with access to food and sugar can live its full span of several weeks; one with nothing to eat lasts about two to three days, by Florida’s figure. Some websites say flies live only a day or so indoors. That is true only of a fly with no food at all, and kitchens rarely qualify: crumbs, spills, fruit, pet food and the bin are all fly food.
If you keep seeing flies day after day, you are almost certainly not watching the same flies. UC IPM notes that flies found inside a building have entered from outside in almost all cases, so a steady supply points to a breeding site close by, a gap in screens, or both. If dozens appear at once, a dead animal or cluster flies in the walls are common explanations, covered in flies in the house all of a sudden.
How long do flies live without food, or when trapped?
A house fly without food survives about two to three days. Drain flies, by Alabama Extension’s account, last three to four days without fluids and about two weeks with them. A fly trapped in a jar or between a window and a screen therefore usually dies within a few days. A fly trapped in a room with a fruit bowl and a bin is not trapped in any useful sense.
How long do fruit flies and drain flies live?
Fruit flies develop quickly: Kentucky Extension says the cycle from egg to adult can be completed in about a week, and New Hampshire Extension gives one to two weeks depending on temperature, with eggs hatching in about a day and larvae feeding for five or six days. Adults under ideal laboratory conditions can live for weeks to months. The practical point is the speed of the cycle, not the adult’s life span.
Drain flies take longer to develop, 8 to 24 days according to Alabama Extension, with larvae living in the slime inside drains for 8 to 15 days. Adults live about two weeks if they can sip fluids.
Both breed in specific places, a fermenting food film for fruit flies and drain slime for drain flies, and telling them apart decides what to clean. Our guide to fruit flies, drain flies and gnats covers that, and small flying bugs in the house helps when you are not sure what you are looking at.
What do flies eat?
Adult house flies feed on liquids. UC IPM explains that they have sponging mouthparts and eat solid food by first liquefying it with saliva, sometimes regurgitating onto it. Sugar matters most for their survival, and females also need protein before they can lay eggs. Maggots feed on the bacteria in the moist, decaying material where they hatch.
Fruit fly larvae feed on the yeast growing in overripe and fermenting produce, which is why one forgotten potato or onion can, in Kentucky Extension’s words, breed thousands of fruit flies. Drain flies live by sipping fluids. Adult mayflies do not eat at all: Texas A&M notes they have non-functional mouthparts.
Why life span matters for control
The numbers explain why swatting and spraying adults rarely solves a fly problem. Each female lays hundreds of eggs, and a new generation can arrive every 7 to 10 days in summer. University of Florida cites a calculation that a single pair of flies starting in April could, if every offspring survived, give rise to 191,010,000,000,000,000,000 flies by August. They never do survive, but the arithmetic shows why the adults you kill are quickly replaced.
UC IPM’s guidance follows from this: the larval stage is the best target, and removing the material where maggots develop breaks the life cycle. It adds that house flies are now resistant to many registered insecticides and that in most homes pesticides are not needed or recommended. Sanitation and screens are the answer:
- Bag kitchen waste, keep bins lidded, and remove waste at least weekly; UC IPM’s outdoor guidance is weekly removal of organic waste, including dog faeces and rotting fruit.
- Seal gaps around windows and doors and keep screens in good repair.
- Use a swatter or sticky ribbons for the few flies that get in. UC IPM advises against bug zappers near food preparation areas because insect fragments can be propelled several feet.
Commercial kitchens face the same biology under stricter rules; our analysis of restaurant fly violations shows when inspectors cite flies most often. At home, a professional is rarely needed for house flies unless the breeding source cannot be found or reached.
When flies are about: what iNaturalist records show
We looked at when people in the US record house flies, drain flies and cluster flies on iNaturalist, adjusting each month for how many observations of anything people logged. A value of 100 is the fly’s average share of records; 200 is double.
House fly records are lowest in winter, 41 in February, and climb to 200 in October and 225 in November. Drain flies follow a similar but gentler curve, from 60 in April to 156 in October. Cluster flies show two peaks, 184 in March and 183 in November, consistent with cluster flies gathering in buildings in autumn and becoming active again in spring. The autumn rise for house flies most likely reflects people noticing flies around and inside homes as other insects disappear, so treat it as a sightings pattern rather than a breeding count.
Frequently asked questions
Which fly lives 24 hours?
None of the common house pests. The insect famous for a one-day adult life is the mayfly, which belongs to a different insect order from true flies. Texas A&M describes adult mayflies as surviving only one or two nights, without functional mouthparts, after a life cycle that typically lasts a year underwater. House flies, by contrast, usually live 15 to 25 days as adults, according to University of Florida.
What smell do flies hate?
No smell has been shown to keep house flies out of a home. In a USDA laboratory study, catnip essential oil repelled about 79 per cent of house flies in laboratory bioassays, but a lab result is not the same as protection across a kitchen. Extension guidance, such as UC IPM’s, relies on screens, sealed gaps, lidded bins and removing breeding material rather than scents.
How long do flies survive in your house?
It depends on food. A house fly that can find sugar and other food indoors can live its normal adult span, usually 15 to 25 days and occasionally up to two months, and lives longer when it is cool. Without food it survives only about two to three days, according to University of Florida. A steady stream of flies means new ones are arriving or breeding nearby.
How do flies die naturally?
Most die of age within weeks, or quickly from starvation, cold or predators and parasitic wasps. A common sight in spring and autumn is a fly stuck to a window with its wings raised and a white halo on the glass. University of Wisconsin Extension explains this is usually the fungus Entomophthora muscae, which infects only certain flies and makes them climb upwards before they die.
How many eggs does a house fly lay?
University of Florida gives up to 500 eggs per female, laid in batches of 75 to 150 over three to four days. Laboratory work at North Carolina State found the total depends strongly on temperature: 184 eggs per female at 68°F, 709 to 729 at 77 to 86°F, and 506 at 95°F. Eggs hatch in 8 to 20 hours in warm weather.
Sources
- University of Florida, Featured Creatures EENY-48: House fly, Musca domestica (Sanchez-Arroyo and Capinera), revised 2017.
- Fletcher, M. G., Axtell, R. C. and Stinner, R. E., Longevity and fecundity of Musca domestica as a function of temperature, Journal of Medical Entomology 27(5), 1990.
- University of California Statewide IPM Program, Pest Notes: Flies, UC ANR Publication 7457 (A. C. Gerry).
- University of Florida IFAS Extension, EENY-502: Common green bottle fly, Lucilia sericata (Anderson and Kaufman), 2011.
- University of Kentucky Entomology, ENTFACT-621: Fruit Flies (M. F. Potter).
- University of New Hampshire Extension, Family, Home and Garden Education Center: Fruit Flies.
- Piper, M. D. and Partridge, L., Protocols to Study Aging in Drosophila, Methods in Molecular Biology 1478, 2016.
- Alabama Cooperative Extension System, Drain Flies in the Home: Identification and Management, 2026.
- Texas A&M AgriLife, Field Guide to Common Texas Insects: Mayfly.
- Zhu, J. J. and others (USDA Agricultural Research Service), Efficacy and safety of catnip as a novel filth fly repellent, Medical and Veterinary Entomology 23(3), 2009.
- University of Wisconsin Extension, Entomophthora muscae (S. Mahr), reviewed 2025.
- The Pest Control Brief analysis of iNaturalist research-grade records, pulled October 2026.
