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Where Do Flies Go in the Winter?

Flies are typically very active during the warmer months of the year, and they take a break in the colder months, so wondering where do flies go in the winter is a common question.

There are over 110,000 species of flies found worldwide, most of which are found in hot climates. This article will explain how these insects survive the harsh weather of the cold season.

Key Takeaways:

  • During the winter, flies hibernate or overwinter.
  • When the temperature falls below 45°F, their body functions begin to slow.
  • Throughout their lives, flies go through four stages: egg, maggot, pupa, and adult.

Where do flies go in the winter?

Flies are cold-blooded, so they rely on their environment to regulate their body temperature. When it gets too cold outside, flies must spend more time resting in order to keep warm enough to survive. This is why flies hibernate during the winter.

Some will gather in groups in the trees, while others are found buried underground. These are the places where they can usually survive without using much energy from their bodies.

Do flies die in the winter?

Flies on metal rod
Flies on metal rod

Flies don’t die in the winter. These creatures may not be seen flying as much during the hot weather season, but they survive the winter by reducing their activities by hibernating or overwintering.


Hibernation is a period of inactivity and decreased metabolism that allows flies to survive the winter when food and water are scarce. They store energy in their bodies during the warm months in order to survive the cold months without eating or drinking anything.

The exact process varies by species, but flies will generally find a warm place to spend the winter months. They do this by clustering together inside houses or barns, for example. Flies remain in their hibernating state until spring returns.


Overwintering is when a fly remains in this resting phase for longer than usual—usually until spring. Most flies undergo complete metamorphosis, which means they go through four stages of development: egg, larva (or maggot), pupa, and adult.

During the winter, flies in the pupa stage can be found buried in soil or in leaf piles, where they can enter a hibernation-like state known as overwintering. This enables them to conserve energy, survive the harsh winter, and emerge as fully developed adults in the spring.

How cold is too cold for flies?

Fly on white concrete
Fly on white concrete

Most flies are hardy enough to survive temperatures as low as 45°F without dying; however, they become sluggish and less active when temperatures fall below this level. A fly requires warmth from its environment in order to survive in cold weather conditions, which is why you’ll see them inside houses, buildings, or under the ground where temperatures may be less harsh.

How do flies get in the house in winter?

Dead flies in the window
Dead flies in the window

Flies may begin to enter your home for shelter and food before winter arrives. Flies can enter your home through small gaps around windows, doors, and vents, as well as other openings as small as a quarter-inch in diameter. They can also enter through cracks in the ceiling or walls, particularly if they’re close to an outdoor light fixture.

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The main reason flies are in your home during the winter is that it’s cold outside, and these insects need to stay warm. They can’t go outside to look for food because it’s too cold (plus they’d freeze to death), so flies must look for food inside.

Life Cycle of a Fly

Flies, like other insects, have four life stages: egg, larvae (also known as “maggots”), pupa, and adult. These insects typically begin to breed once they become active again in the spring and reach their peak during the warm summer months. Breeding will begin to decline in October as the air begins to cool, and most of these insects prepare to hibernate or overwinter.


House fly eggs on meat
House fly eggs on meat

The egg stage is the first stage in the life cycle of a fly. A female fly lays a swarm of eggs, but she abandons them to hatch on their own.

Female flies can lay between 75 and 150 eggs at a time, depending on the species. The eggs are hidden in unusual places, such as rotting food or animal dung.

This location provides a food source for the larvae once they hatch, and the heat from these locations keeps the eggs healthy. The time it takes for the eggs to hatch varies depending on the species, but it can take anywhere from 24 to 48 hours.


When the egg hatches, it transforms into a maggot. Maggots eat anything from animal carcasses to rotten fruit and live on dead or decaying matter. Their primary function is to eat in order to prepare for pupation.

They’re typically creamy white or pale brown in color and very small, measuring between 4 and 12 mm in length. These creatures remain as maggots for 8 to 10 days before pupating.


Flies pupae isolated on white
Flies pupae isolated on white

During the pupa stage, flies are immobile and eat nothing. They spend most of their time in an enclosed chamber resembling a small hard shell and protecting the developing fly within. It’s usually found under piles of dirt in the summer and under the ground in the winter until it can emerge as an adult fly.


As adults, flies have fully developed wings and can fly. They eat, lay eggs, and go about their normal lives.

These adult insects are tiny and extremely active. Adult flies can live almost anywhere—in soil or on food, and they may also eat dead animals or feces. Because this is the final stage of the fly’s life cycle, they only live for 20-30 days before dying naturally.

Final Thoughts

Understanding what flies do during the winter will allow us to comprehend better how they live. A fly’s winter routine is very different from its normal routine.

To conserve energy, it slows down all of its physical functions, including its heartbeat and breathing rate. This is significant because flies must be able to remain as adults once spring arrives, where they can reproduce again.