Flymageddon: How to Get Rid of Blow Flies in Sydney Homes

Why are there suddenly so many flies in my Sydney home?

What exactly are blow flies and bottle flies?

Blow flies (also called bottle flies) are slightly larger than common houseflies, with distinctive shiny metallic bodies in green, blue, bronze or black shades. You’ll often spot them gathering on windows or making a loud, low buzzing sound when flying indoors.

They play an important role in nature by breaking down dead organic material, but they carry bacteria and can spread pathogens onto food and surfaces inside homes.

Research from the University of Sydney shows blow flies can carry over 100 different bacteria species, including salmonella and E. coli, picked up from breeding sites (Source: University of Sydney, 2022).

Why do blow flies suddenly appear in my Sydney home?

Blow flies only move indoors when there is a suitable breeding or food source nearby. They enter through gaps around doors, windows, vents, or roof spaces, especially during Sydney’s warm humid months from October to April.

Unlike houseflies that breed in general waste, blow flies almost always target decomposing protein-rich material. A single female can lay up to 200 eggs at one time, which hatch into maggots in as little as 8 hours in warm weather (Source: NSW Environment Protection Authority).

For a full inspection, Contact Sydney’s Best Pest Control.

Where should I look for the blow fly breeding source?

Always find and remove the breeding site first — killing adult flies alone will not stop new ones emerging. Check these common locations in order:

• Dead animals: Mice, rats, birds or possums trapped in wall cavities, roofs or under floorboards. Even one small mouse can produce hundreds of flies over 2–3 weeks.
• Waste and bins: Unemptied kitchen scraps, uncovered meat waste, or overflowing compost bins that have not been turned regularly.
• Sewer or drainage issues: Broken pipes or leaking drains that expose sewage or organic matter under floors or sub-floors.
• Hidden rotting material: Fallen fruit, dead vegetation, or pet waste left under decks or verandahs.

We regularly assist Eastern Suburbs and Northern Beaches homeowners who find flies rising from skirting boards after a rat bait program — this is a very common scenario in Sydney (Source: NSW Health).

How do blow flies compare to common houseflies?

Feature	Blow / Bottle Fly	Common Housefly
Colour	Shiny metallic blue, green or black	Dull grey with dark stripes
Main breeding site	Dead animals, rotting meat	General rubbish, manure, food scraps
Time to hatch	8–24 hours	12–24 hours
Typical indoor sign	Sudden large numbers in one area	Gradual numbers around kitchens/bins

How do I get rid of blow flies myself?

Follow these steps once you have removed or accessed the breeding source:

1. Seal bins tightly and remove food waste daily in hot weather; wash bin interiors monthly.
2. Use fly paper or sticky traps near windows — they work well as blow flies naturally fly toward light.
3. Apply surface sprays to resting spots such as window frames and ceilings; this reduces adult numbers but will not stop new flies hatching.
4. Check and seal gaps around pipes, vents and eaves with sealant or mesh.

Note: Aerosol sprays only kill flies you can see. Without removing the source, new flies will keep emerging for up to three weeks (Source: Department of Primary Industries and Regional Development).

When should I call a professional pest controller?

Call us if you smell rotting odour but cannot find the source, or if flies keep appearing after you have cleaned all visible waste. Removing animals from wall cavities or repairing access points requires specialised tools and odour control.

We also use odour-neutralising treatments and follow NSW Public Health regulations to ensure safe, compliant removal. Call us now on 1800 819 189 for urgent help with inaccessible breeding sites.

Frequently Asked Questions

Do blow flies bite people or pets?

No, blow flies do not bite. However they can contaminate food and surfaces with bacteria picked up from breeding sites.

How long will blow flies stay once the source is removed?

Most will die or leave within 2–7 days, but some may emerge from remaining larvae for up to 3 weeks in warm Sydney weather.

Are blow flies a sign my home is dirty?

Not always. Even very clean homes get blow flies if a small animal dies inside a wall or roof space, or if sewer lines are damaged.

Can I use pest bombs to get rid of them?

Pest bombs will kill exposed adults but will not reach hidden breeding sites or larvae. They also do not fix the root cause.

Why do flies gather around windows?

Many flies are attracted to natural light and will often gather around windows after entering a home. This behaviour can make fly traps or light-based capture methods useful for reducing visible numbers while the source is addressed.

Can a dead animal cause a fly infestation?

Yes. A dead mouse, bird, possum or other animal hidden in a roof, wall cavity or ceiling space can attract blow flies. A sudden fly outbreak combined with a bad smell may indicate a hidden carcass.

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A sudden blow fly infestation in Sydney homes is usually linked to a nearby breeding source such as decomposing organic matter, rubbish, compost or a hidden dead animal. Effective fly control requires identifying and removing the source, followed by targeted treatment to reduce adult fly activity.