How long do fruit flies live?
By The Pest GuyLast updated
Weeks, as adults, and longer in a cool room than a warm one. In a 2026 lab study, about half the fruit flies kept at 28°C were dead by 35 days old, while the ones at 18°C and 24°C were still going at 45 days. The number that decides how long you have them is a different one: egg to adult takes 9 days at 25°C and 19 days at 18°C, according to the Bloomington Drosophila Stock Center at Indiana University.
Those lab flies had food on tap the whole time. In a kitchen with a fruit bowl, so do yours. So the adult you swat today could have weeks left in it, and the ones replacing it may already be in the bin or the drain, a week or two from flying.
That is why the lifespan of one fly hardly matters. A swarm in your kitchen lasts as long as it keeps breeding, and that can be indefinitely.
How long a fruit fly takes to grow, by room temperature
Bloomington gives the time from egg to adult as about 7 days at 29°C, 9 days at 25°C, 11 days at 22°C and 19 days at 18°C. So a cool room more than doubles the wait compared with a warm one. Pick the line closest to your kitchen and that is your generation time.
The University of Kentucky puts the whole thing at about a week. That is the warm end of the same scale.
A new adult does not hang about either. Bloomington says fruit flies do not mate for about 10 hours after they come out of the pupa at 25°C. So a female that hatches this morning can be mated by tonight.
Why a week of trapping is not enough
Say you bin the rotten fruit today and put a trap out. Any egg laid yesterday somewhere you have not found, in the food bin, the drain or a damp dishcloth, becomes a flying adult in about 11 days at 22°C, and nearer three weeks at 18°C. Take the trap away after a week and you have caught the parents and missed the children.
So run it through one full generation after the last fly you catch, at your room's temperature. In a warm kitchen that is about two weeks. In a cool one, three. If it is still catching new flies at the end, something is still breeding, and the trap is telling you so.
The order matters. Kentucky says that unless the breeding sites are removed or cleaned, the problem will continue no matter how often insecticides are applied to the adults, and only after that does it reach for a cider vinegar trap to catch the ones left over. Finding where fruit flies are breeding in the house comes first, and the trap mops up after it.
How long do fruit flies live without food
About four days, on average. That is how long ordinary fruit flies lasted with no food in the control group of a 2015 PLOS ONE study, against up to 18 days for flies bred over generations to survive starvation.
The catch is that a kitchen is rarely empty. Kentucky says all they need to breed is a moist film of fermenting material, and lists drains, bins, empty bottles and cans, mops and cleaning rags. Starving them out means finding every one of those, which is the same job as finding the source.
Do fruit flies ever go away on their own?
Not while they have somewhere to breed. The Scottish Government's nuisance guidance says fruit flies can be a problem year-round in domestic kitchens, and that a bin which is not emptied or cleaned can breed thousands of them. Kentucky says they are especially common in late summer and autumn, and why late summer is the peak has the rest of that story.
Cooler weather slows them down, going by Bloomington's figures, but that guidance is the reminder that a kitchen can keep them going all year. So waiting for winter is not a plan. Every female you miss is a few hundred more eggs, and where fruit flies lay their eggs is where to look for them. Bin that first, then trap the fruit flies that are left.
A trap you can leave out for the whole generation
Bin the source first. Then fill this with about 25 ml of cider vinegar and a drop of washing-up liquid, stand it where they gather and leave it there through the flies still to hatch. A 500 ml bottle of cider vinegar fills it 20 times, so keeping it going for the whole stretch is cheap. It catches adult fruit flies, not the eggs or larvae, which is why the source still has to go.
What I’d use
Reusable cider vinegar trap
Escape-proof fruit fly trap
A two-part cup and lid you fill with about 25 ml of cider vinegar and stand by the fruit bowl.
Eight slots in the lid feed a funnel that drops flies through one 4 mm hole into the dark middle of the cup. The brightest points a trapped fly can see are pinholes too small to get through, set away from the real exit, so the way out is the place they are least likely to look.
- Ways in
- Eight slots in the lid, into one funnel
- Way out
- One 4 mm hole, under the solid centre of the lid
- Holds
- About 25 ml of vinegar, to the moulded fill line
- Size
- 6.7 cm across, 5.4 cm tall
- Refills
- None to buy. It runs on cider vinegar from the cupboard
Watch out for
- Vinegar and washing-up liquid not included.
- Made for fruit flies. Flies from a plant pot or drain need the source found.
- Tip, rinse by hand and refill once it fills up.
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