At What Temperature Do Fruit Flies Die?

By the Fruit-Flies.com editorial team · Updated October 2026

Adult fruit flies die within a couple of hours below about −5 °C (23 °F), and they collapse from heat at around 40 °C (104 °F). Everything in between is survivable — temperature mostly decides how fast they breed. At a warm 25–29 °C (77–84 °F) a new generation is ready in a week or so; at 18 °C (64 °F) it takes nearly three weeks, and in the low single digits they stop moving altogether.

How cold kills a fruit fly

Fruit flies are tropical insects that never evolved real frost protection. As the temperature drops they simply run slower: they feed less, lay fewer eggs, and each stage of the life cycle takes longer. A few degrees above freezing an adult can no longer fly or even stand, and drops into a reversible "chill coma" — warm it up and it walks away. That is why the sluggish flies you find in a cold garage or a fridge often come back to life on the counter.

Real damage starts at and below freezing. In laboratory studies, adult fruit flies and pupae die when chilled below about −5 °C (23 °F) for as little as two hours, and larvae are more fragile still: young larvae that have not been gradually cooled first can die within minutes at 0 °C (32 °F). Ice is the end of the line, because their bodies cannot survive being frozen.

There is one in-between state worth knowing. In cool weather with short days — around 10–14 °C (50–57 °F) — females of temperate populations can pause egg-laying in a light, reversible dormancy called reproductive diapause. It is how a few adults ride out winter in a shed or a crack in a wall, and it explains a lot about what happens to fruit flies in winter.

How hot is too hot?

Fruit flies like it warm, but only up to a point. Their development is fastest at around 28–29 °C (82–84 °F), where the whole cycle from egg to adult can take as little as a week. Push much past 30 °C (86 °F) and heat stress sets in: development slows again, and the flies struggle to breed well.

The hard limit sits around 40 °C (104 °F). In laboratory tests where the temperature is raised slowly, fruit flies lose motor control and fall at an average of about 41 °C (106 °F), with individual strains ranging from roughly 40 to 41.5 °C. A sun-baked car, a greenhouse in summer or a dishwasher cycle will kill them; an ordinary heatwave indoors will not.

Temperature and breeding speed

For most homes the useful question is not what kills fruit flies but how quickly they multiply. That is set almost entirely by temperature:

Because generations overlap and each female lays hundreds of eggs, those few days make an enormous difference — see how fast fruit flies multiply. It is also why the annual peak lands in late summer and early autumn, covered in fruit fly season.

Does the fridge kill fruit flies?

Not reliably. At about 4 °C (39 °F) adults are immobilised and nothing develops, so the fridge is an excellent place to store ripe fruit: it stops the overripening that attracts flies and halts any eggs on the skin. But it is a pause button, not an off switch. Eggs and larvae can survive days of chilling and carry on once the fruit warms up again, so wash produce as well as chilling it. The details are in can fruit flies get in the fridge.

Does freezing kill fruit flies and their eggs?

Yes. A domestic freezer runs at about −18 °C (0 °F), far below the roughly −5 °C that kills adults and pupae within hours, so freezing reliably finishes off every stage. Bagging infested fruit or scraps and leaving them in the freezer for a full day before you throw them out means nothing can hatch in your bin. The same trick works for a vacuum bag full of flies.

Can you use heat or cold to get rid of them?

Only in small, targeted ways. You cannot chill a house cold enough to matter — it would have to sit near freezing for hours — and heating rooms to a lethal 40 °C is neither safe nor sensible. Temperature works on the things flies breed in, not on the house:

1. Refrigerate ripe fruit so it stops fermenting and can't host new eggs.
2. Freeze infested scraps for a day before binning them.
3. Use hot water on drains — boiling water down a sink drain (not into a garbage disposal or onto plastic fittings) loosens the film larvae live in, ahead of scrubbing.
4. Keep the kitchen cooler in hot spells if you can; it slows breeding while you find and remove the source.
5. Trap the adults with a simple apple cider vinegar trap while the source is cleared.

Frequently asked questions

What temperature kills fruit flies instantly?

Nothing household-friendly is truly instant. Heat around 40 °C (104 °F) knocks them down within minutes, and below −5 °C (23 °F) they die within about two hours. A freezer at −18 °C is the most practical reliable option.

At what temperature do fruit flies stop breeding?

Breeding slows steadily as it cools and effectively stops in the low teens Celsius (the 50s Fahrenheit) and below, especially when days are short. Indoors at normal room temperature they breed all year.

Do fruit flies die in a cold garage or on a cold night?

A cold night slows them and may knock them into a chill coma, but they recover when it warms. Only sustained frost — below about −5 °C — reliably kills them.

Can fruit flies survive in a hot car?

No. A car parked in the sun easily passes 40 °C (104 °F) inside, which is above their heat limit. Fruit flies in a car usually come from forgotten food and can be dealt with as in fruit flies in the car.