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Identify Your Pest Flying insects Fruit fly

Flying insects

Fruit fly

Drosophila spp. · Also called: Vinegar fly

Fruit flies are tiny tan flies with red eyes that hover around ripe fruit, recycling and drains. They breed in anything moist and fermenting, so a small problem can grow fast in a warm kitchen.

Tiny tan fruit fly with bright red eyes resting on the skin of a ripe banana
Quick facts

Size About 3 mm long

Colour Tan to light brown with darker bands on the abdomen

Key feature Tiny tan fly with bright red eyes, often hovering over fruit

Season Year round indoors; often worst in late summer and fall

Where Fruit bowls, compost pails, recycling, drains, bars and garbage areas

How to identify it

What it looks like

Fruit flies are only about 3 mm long. The body is tan to light brown, and the back half has darker bands. Most have bright red eyes, which are easy to see when a fly lands on a light surface. They fly slowly and tend to hover in small groups.

You usually find them over ripe fruit, open wine or beer, compost pails and recycling bins. The larvae are tiny, pale and hard to spot. They live in the wet surface layer of fermenting food, or in the film that builds up in drains, mops and garbage containers.

Often confused with

Drain fly

Drain flies are grey and fuzzy, with broad, rounded wings that make them look like tiny moths. They rest on bathroom walls and do not have red eyes.

Fungus gnat

Fungus gnats are dark, slender and long-legged, like tiny mosquitoes. They gather around houseplants and damp potting soil rather than fruit.

Phorid fly

Phorid flies have a humped back and often run in quick, jerky bursts across surfaces instead of flying. They can point to a drain or sewer problem.
Know the signs

Signs to look for

Small flies over fruit

Tiny flies hovering over a fruit bowl, potatoes, onions or tomatoes, especially ones that are soft or bruised.

Flies near the sink

Flies resting around the kitchen sink or rising from a drain or garbage disposal.

Flies around recycling

Groups gathering around empty bottles, cans, compost pails or sticky juice spills.

Flies near mops and wet areas

Activity near damp mops, rags, dish racks or floor drains, a common pattern in restaurants and bars.
Why it matters

Risks and damage

Fruit flies do not bite or sting and are mainly a nuisance. However, they move between garbage, drains and fresh food, so they can carry bacteria and yeasts onto food and drinks. In restaurants, bars and grocery stores, they can spoil product and cause problems during health inspections. In homes, the main concerns are contaminated fruit and the annoyance of large numbers.

In Alberta

Fruit flies show up in Alberta homes and food businesses all year because heated buildings keep them active. Many people notice them most in late summer and fall, when garden produce and market fruit come indoors. They can also arrive as eggs on store-bought fruit.

Did you know?

Fruit flies have been used in genetics research for more than a century. Work on these tiny flies has helped earn several Nobel Prizes, starting with Thomas Hunt Morgan in 1933.

Prevention

How to keep them out

Refrigerate ripe produce

Keep ripe fruit and vegetables in the fridge. Throw out or compost anything soft, bruised or leaking.

Rinse recycling

Rinse bottles, cans and jars before they go in the bin. Keep recycling in a lidded container or outside.

Empty compost pails often

Take kitchen compost out every day or two and wash the pail each time.

Scrub sink drains

Clean sink drains and garbage disposals with a stiff brush and hot water to remove the film where larvae live.

Wash and dry mops and rags

Launder mops, sponges and cloths, then let them dry fully. Damp, dirty rags can become breeding spots.
When to call

When it is time to bring in a professional

Call a professional if fruit flies keep returning after you remove fruit and clean drains, or if you run a restaurant, bar, grocery or food plant. Hidden breeding sites, such as under equipment or in floor drains, can be hard to find. Technica’s licensed technicians can help track down the source.

Common questions

Frequently asked questions

Where do fruit flies come from?

Some arrive as eggs or larvae on fruit brought home from the store or garden. Others fly in through gaps and torn screens. Once inside, they find ripe produce, spills or drains and start breeding.

How fast do fruit flies multiply?

Very fast. In warm conditions they can go from egg to adult in about 8 to 10 days. One female can lay hundreds of eggs, so a few flies can turn into many within a couple of weeks.

Why do I still see fruit flies after I threw out the fruit?

There is likely another breeding spot. Check drains, compost pails, recycling, the bottom of garbage cans, mops and the floor under appliances. Any spot with moist, fermenting residue can keep them going.

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