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Flies

Two-winged insects that breed in rotting organic matter. House flies, blowflies, vinegar flies and drain flies each point to a different breeding source, and finding that source is the key to getting rid of them.

Written by PestMan Editorial TeamTechnical review pendingPublished Updated
Common types
House, blow, vinegar, drain and bush flies
Life cycle
About 1–2 weeks in warm weather
Key to control
Find the breeding source
Health relevance
Food contamination
Risk level
Low to moderate

Fly identification

How to recognise flies

  • One pair of wings (flies are "true flies", order Diptera), with short antennae.
  • House fly: 6–7 mm, grey, with four dark stripes on the thorax.
  • Blowfly: 8–12 mm, often metallic green, blue or bronze, and noisy in flight.
  • Vinegar ("fruit") fly: 2–3 mm, tan with red eyes, hovering around fruit and bins.
  • Drain (moth) fly: 2–4 mm, grey and fuzzy with leaf-shaped wings, resting on bathroom walls.

Common species in Australia

House Fly

Musca domestica

The common grey fly found indoors worldwide. It breeds in rubbish, compost, manure and pet waste, and can carry bacteria onto food.

Blowflies

Family Calliphoridae

Large, often metallic green, blue or bronze flies that breed in meat and dead animals. A sudden swarm indoors usually means something has died nearby.

Vinegar Fly ("Fruit Fly")

Drosophila spp.

Tiny tan flies with red eyes that hover around fruit bowls, bins and drains. Often called fruit flies, but different from the Queensland fruit fly, which attacks fruit on trees.

Drain Fly (Moth Fly)

Family Psychodidae

Small, fuzzy, moth-like flies that breed in the organic slime lining drains and appear on bathroom and laundry walls.

Fly overview

Flies are the most familiar insects in Australian homes. The adults you see are the last stage of a life cycle that starts as maggots in something moist and decaying: rubbish, compost, pet waste, a dead animal, overripe fruit or the slime inside a drain.

That makes flies unusually easy to diagnose. The type of fly tells you what to look for; see what kind of fly is this. Lots of large metallic blowflies suddenly appearing indoors usually means a dead animal nearby; see why there are suddenly lots of flies. Tiny flies around the fruit bowl are vinegar flies, and small fuzzy flies near the shower are drain flies.

Bush flies, the ones that crowd around your face outdoors in summer, breed in dung in paddocks and are a different problem from flies breeding in or around the house.

Behaviour

  • Adults are attracted by smell to food, rubbish, faeces and dead animals.
  • House flies and blowflies are most active in warm, sunny weather.
  • Many flies rest on ceilings, light fittings and window frames, where their spots accumulate.

Habitat

  • Bins, compost, pet waste and chicken runs (house flies).
  • Dead animals, meat scraps and rubbish (blowflies).
  • Overripe fruit, fruit-fly traps of forgotten food, drains and recycling (vinegar flies).
  • Organic film inside drains, sump pits and grease traps (drain flies).

Lifecycle

  • Egg → larva (maggot) → pupa → adult.
  • In warm weather, house flies and blowflies can complete their life cycle in about one to two weeks, so populations build quickly from a single breeding source.
  • Maggots often leave the breeding site to pupate, which is why they turn up crawling across floors.

Food sources

  • Liquids and soft foods: sugars, rotting fruit, meat, faeces and other decaying matter.

Entry points

  • Open doors and windows without screens.
  • Gaps around screens and doors.
  • Breeding inside the house: drains, bins, fruit bowls, or a dead animal in a wall or roof void.

Infestation signs

  • Adult flies indoors, often at windows.
  • Maggots on floors or near bins.
  • Small dark fly spots on ceilings and light fittings.
  • A bad smell in one area of the house (possible dead animal).

Health implications

  • House flies and blowflies move between waste and food and can carry bacteria such as Salmonella and E. coli on their bodies and in their vomit and droppings.
  • Keeping flies off food and food-preparation surfaces is part of basic food safety.

Prevention

  • Keep bins sealed and clean, and wrap meat and fish scraps before binning.
  • Pick up pet waste daily and manage compost properly.
  • Fit and repair fly screens, and use self-closing screen doors.
  • Don’t leave fruit to overripen on benches; empty and rinse recycling.
  • Clean drains regularly with a brush and hot water.

Treatment overview

  • Finding and removing the breeding source is the main treatment for every type of fly.
  • Fly screens, traps and baits can reduce adult numbers, and products must be used according to the label.
  • For flies from a dead animal in a wall or roof, the problem ends when the carcass is removed or dries out.
Product safety

If you use any pest product, read the label first and follow it exactly — it is a legal requirement in Australia. Keep products away from children, pets and food areas as the label directs.

Questions about flies

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Sources & further reading

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