Quick answer: Most adult flies live two weeks to two months. The average house fly lives 15 to 25 days, or about a month counting the egg, maggot and pupa stages before it can fly. Drain flies live about two weeks, and fruit flies often outlast both. On Oahu, warm weather all year means flies never stop breeding.
You swat one fly, and by lunchtime there are three more. It can seem like they never die, but they do. The catch is that a fly spends most of its short life making more flies. This guide covers how long flies live, the lifespan of each common fly, how long a fly lives without food or indoors, and why Hawaii's climate keeps them coming back.
How Long Do Flies Live?
Most adult flies live about two weeks to two months, depending on the species, the temperature and how much food they can find. A house fly usually lives 15 to 25 days and can reach two months. Drain flies live about two weeks. Fruit flies can live 45 to 60 days in ideal conditions.
According to the University of Florida house fly fact sheet, adult house flies "usually live 15 to 25 days but may live up to two months." That is the life span of a fly as an adult. Before it ever flies, it has already spent about a week as an egg, a maggot and a pupa, usually hidden somewhere you don't look.
So when people ask how many days a fly can live, the honest answer is anywhere from about 14 days to 60. The fly's lifetime is short, but it is long enough to lay hundreds of eggs.
Fly Lifespan by Species
The kind of fly tells you how long it will live and, more important, where it is breeding. Here is the average fly lifespan for the flies you are most likely to see around an Oahu home or business:
| Fly | Adult lifespan | Egg to adult | Where it breeds |
|---|---|---|---|
| House fly | Usually 15 to 25 days, up to about 2 months | As little as about a week in warm weather | Garbage, pet waste, manure, rotting food |
| Fruit fly | 45 to 60 days in ideal lab conditions; shorter at home | About a week | Overripe fruit, drains, drink dispensers, recycling |
| Drain fly | About 2 weeks | 1 to 3 weeks for the full cycle | Slime inside drains and overflow pipes |
| Blow fly | Varies by species | About 2½ weeks | Dead animals, meat scraps, garbage |
Sources: UF/IFAS (house fly), Harvard BioNumbers and University of Kentucky (fruit fly), Ohio State University (drain fly), NC State Extension (blow fly).
How Long Does a House Fly Live?
The average house fly lives 15 to 25 days as an adult and can live up to about two months. Counting the week it spends as an egg, maggot and pupa in warm weather, the whole lifetime of a house fly is often about a month.
The house fly is the gray, quarter-inch fly you see around kitchens, lanais and dumpsters. Housefly life expectancy is longest when it is warm, there is plenty to eat and nothing is hunting it. In that time, one female can lay up to 500 eggs in batches of 75 to 150, according to UF/IFAS. That is why a small fly problem can turn into a big one in a couple of weeks.
What Is the Lifespan of a Fruit Fly?
Lab studies put the mean lifespan of a fruit fly at 45 to 60 days at about 77°F in ideal conditions, and shorter in everyday settings, according to Harvard BioNumbers. A fruit fly can go from egg to adult in about a week, and a female can lay about 500 eggs.
Fruit flies are the tiny tan flies with red eyes that circle the fruit bowl, the recycling bin and the sink. The University of Kentucky notes the whole cycle from egg to adult can be finished in about a week. They breed in overripe or fermenting produce, like a forgotten mango or banana peel, and in the film around drains and drink dispensers. In restaurants and bars they show up around soda and beer lines.
Fruit fly lifespan without food: short. In one lab study, ordinary fruit flies kept with water but no food survived about two to four days (study).
Drain Fly Lifespan
Drain flies, also called moth flies, are small, fuzzy and gray. You'll usually find them resting on bathroom walls near the shower or sink. The Ohio State University fact sheet says adults live about two weeks, with old ones dying and new ones emerging, and the life cycle takes one to three weeks. Their eggs and larvae live in the slime inside drains and overflow pipes, so spraying adults does very little.
Blow Fly Lifespan
Blow flies are the big, shiny green or blue flies. Females lay hundreds of eggs on dead animals. According to NC State Extension, the eggs hatch in about 24 hours, the maggots feed for about a week, and adults come out about eight days after that. A sudden swarm of blow flies indoors often means a dead animal in a wall, crawlspace or attic. On Oahu that is usually a rat or mouse, so rodent control for Oahu homes and businesses is often the real fix.
The Life of a Fly: How Long Each Stage Lasts
Every fly goes through four stages: egg, larva (maggot), pupa and adult. Here is how long each one takes for the house fly, based on the UF/IFAS fact sheet:
| Stage | How long it lasts | What happens |
|---|---|---|
| Egg | 8 to 20 hours in warm weather | Laid in batches of 75 to 150 on garbage, waste or rotting food |
| Larva (maggot) | 4 to 13 days at warm temperatures | Feeds on the moist, decaying material it hatched in |
| Pupa | 2 to 6 days in heat; much longer when cool | Develops inside a hard brown case, often in drier soil nearby |
| Adult | Usually 15 to 25 days, up to about 2 months | Feeds, mates and lays eggs |
When it's warm, a house fly can go from egg to egg-laying adult in about a week and a half. When it's cool, the same cycle can stretch out for weeks longer.
How Long Can a Fly Live Without Food?
An adult house fly without food survives only about two to three days, according to UF/IFAS. Fruit flies are similar: in lab tests, ordinary fruit flies with water but no food lasted about two to four days. That is why cutting off food is the fastest way to shorten a fly's life.
- House fly, no food: about 2 to 3 days
- Fruit fly, water but no food: about 2 to 4 days in lab tests
Take away open trash, spills, pet food and ripe produce, and a fly's life drops from weeks to days.
How Long Does a Fly Live Indoors?
Indoors, a house fly with food and water can live its full 15 to 25 days, and sometimes up to two months. Inside, it's out of the rain and wind and away from birds, geckos and spiders. A fly trapped in a clean room with nothing to eat usually dies within two to three days.
So how long can flies live in your house? It comes down to what they can find to eat. A kitchen with crumbs, a pet bowl and an open trash can lets them live out their full lifespan. Outdoors, many flies die early, but that is also where most breeding happens: dumpsters, green waste, compost and pet waste. The flies inside are usually adults that found a way in, while the real source is outside, in a drain or in a can.
What Affects Fly Longevity?
Fly longevity isn't fixed. How long adult flies live comes down to a few things:
- Temperature: warmth speeds up every stage, so flies grow and breed faster. Cold slows them down.
- Moisture: eggs and maggots need damp material. Wet garbage, drain slime and moist soil keep them alive.
- Food: adults need a steady supply of food and liquid. Without it they last only a few days.
- Shelter: flies indoors avoid weather and predators, so they often live longer than flies outside.
- Species: a tiny drain fly and a big blow fly live very different lives in very different places.
Why Do Flies Live Such Short Lives?
Flies are built to breed fast, not to live long. They are cold-blooded, so outside temperature sets the pace of their lives. A female house fly can lay up to 500 eggs over three to four days, so even a short adult life is enough time to start the next generation.
Researchers note that outside temperature affects how long cold-blooded insects like fruit flies live (PubMed). And lab fruit flies, kept in ideal conditions, live longer than the ones in your kitchen (BioNumbers).
Do Flies Only Live 24 Hours?
No. The idea that flies live only 24 hours is a common myth. House flies live for weeks as adults, and fruit flies can live more than a month. The insect behind the myth is probably the mayfly. The University of Kentucky says adult mayflies "only live for a day or two, just long enough to mate and lay eggs." They aren't the flies buzzing around your trash.
When Do Flies Go Away?
On the mainland, flies drop off when winter comes. On Oahu, there's no cold season to do that job. Flies go away when two things happen: the adults already flying around reach the end of their lifespan, and no new flies are hatching to replace them.
Once you remove the breeding source, most house flies and drain flies will be gone within a few weeks. Fruit flies can take longer because the adults live longer. If flies are still showing up after that, something nearby is still breeding them.
Why Flies Thrive Year-Round on Oahu
House flies lay the most eggs at about 77°F to 86°F (UF/IFAS). Honolulu's average monthly temperature runs from about 74°F in January to 82°F in August, and stays at 78°F or warmer from May through November (State of Hawaii Data Book). Add island humidity, and flies breed in every season.
- No cold season: flies breed all year instead of dying off each winter.
- Humidity: moist garbage, green waste and drains keep eggs and maggots alive.
- Older homes and buildings: worn screens, gaps around doors and older plumbing let flies in and give them damp places to breed.
- Busy commercial areas: restaurant dumpsters, grease areas and loading docks can feed flies for a whole block.
The same warm, humid weather keeps roaches, ants and Formosan termites active here all year too.
Why Killing Adult Flies Isn't Enough
Swatters, sticky traps and bug spray only get the adults you can see. Meanwhile, eggs, maggots and pupae keep developing in the trash, the drain or the compost pile. A fly can go from egg to adult in about a week in warm weather, so new flies keep replacing the ones you kill.
This is where the average lifespan of a fly matters. Remove the breeding source and the adults already flying around will die off on their own within weeks. Leave the source and the flies keep coming.
How to Cut Flies Off at the Source
Get rid of breeding spots
- Take trash out often and keep lids tight on every can, inside and out.
- Rinse garbage and recycling bins so no film or residue builds up.
- Pick up pet waste and fallen fruit in the yard.
- Keep ripe fruit in the refrigerator, and don't leave produce out for days.
Deal with moisture and drains
- Scrub drains with a stiff brush to remove the slime where drain flies breed.
- Fix leaky pipes, dripping faucets and standing water.
- Clean under appliances and around floor drains in kitchens and bathrooms.
Keep them out
- Repair torn window and door screens.
- Seal gaps around doors, windows, vents and utility lines.
- Keep doors closed near dumpsters and loading areas.
Many of these steps also keep out roaches and rodents. Our homeowner pest prevention checklist covers the rest.
For Restaurants, Hotels and Other Businesses
In a restaurant, warehouse, hotel or school, flies are a sign that something is feeding pests. The dumpsters, drains, grease areas and loading docks that breed flies also attract roaches and rodents. Our guide to fly control in Hawaii kitchens explains why food businesses face extra pressure here, and these tips to keep your restaurant pest free and warehouse sanitation tips cover the day-to-day habits. Pests breed quickly in Oahu's heat, so commercial sites do best with regular service, not a one-time fix. Learn how ongoing prevention plans are set up for different properties.
When Flies Point to a Bigger Pest Problem
Flies are often a warning sign. The conditions that feed them also feed other pests:
- Garbage and food waste attract roaches as well as flies. If you're seeing both, look into professional roach treatment.
- A sudden swarm of large flies indoors can mean a dead rodent in a wall, attic or crawlspace.
- Moist, damaged wood and leaky plumbing that attract drain flies can also attract termites.
If you're seeing flies along with roaches, rodents or other pests, a trained technician can find the source you're missing. Xtermco has been solving pest problems on Oahu since 1961. See our complete lineup of residential and commercial pest services.
Frequently Asked Questions About Fly Lifespan
How long can a fly live?
Most adult flies live two weeks to two months. House flies usually live 15 to 25 days and can reach about two months. Drain flies live about two weeks, and fruit flies can live 45 to 60 days in ideal lab conditions, usually less in a home.
How long can a fly live without food?
An adult house fly without food survives only about two to three days. In lab studies, ordinary fruit flies kept with water but no food lasted about two to four days. Take away trash, spills and ripe fruit, and the flies in your home die off fast.
What is the lifespan of a fruit fly?
Lab studies put the mean adult lifespan of a fruit fly at 45 to 60 days at about 77°F in ideal conditions, and shorter in everyday settings. A fruit fly can go from egg to adult in about a week, and a female can lay about 500 eggs.
How long does a fly live indoors?
Indoors, a house fly with food and water can live its full 15 to 25 days, and sometimes up to two months, because it is safe from weather and predators. A fly trapped in a clean room with nothing to eat usually dies within two to three days.
How long does a house fly live on average?
The average house fly lives about 15 to 25 days as an adult, or roughly three weeks. Add the week or so it spends as an egg, maggot and pupa in warm weather, and one house fly's whole lifetime is often about a month.
Do flies only live for 24 hours?
No. That is a myth. House flies live for weeks, and fruit flies can live more than a month. The insect people may be thinking of is the mayfly, whose adults live only a day or two, just long enough to mate and lay eggs.
Why do flies have such short lives?
Flies are built to breed fast, not live long. They are cold-blooded, so outside temperature sets the pace of their lives. A female house fly can lay up to 500 eggs over three to four days, so a short life is still plenty of time to start a new generation.
When do flies go away?
Flies go away when the adults die off and nothing new is hatching. Once you remove the breeding source, most house flies and drain flies are gone within a few weeks. Fruit flies can take longer because adults live longer. If they keep coming, something nearby is still breeding them.
Do flies live longer in Hawaii?
A single fly does not live much longer here, but Oahu stays warm all year, so flies never get a winter break. Honolulu's average monthly temperature runs from about 74°F to 82°F, close to the range where house flies lay the most eggs. That means more generations every year.
How fast do flies multiply?
Very fast. One female house fly can lay up to 500 eggs in batches of 75 to 150. In warm weather the eggs hatch in 8 to 20 hours, and the young can reach adulthood in about a week. A few flies can become hundreds in a couple of weeks.
Need Help With Flies or Other Pests on Oahu? Call Xtermco
Flies, roaches, ants, rodents and termites all thrive in Hawaii's warm, humid weather. Xtermco is a locally owned Oahu company that has been handling pest problems for more than 60 years. We're licensed (Lic # PCO-201), and our employees go through pre-employment and quarterly drug testing. We offer same-day service and free estimates. Here's why Oahu families choose a local exterminator.
Call (808) 591-2922 or request your free estimate online, and we'll tell you exactly what happens next.