How to Get Rid of Blow Flies

Confirm you have blow flies

Start by confirming the bug. Blow Flies have a few features that set them apart. Adults measure 8–12 mm (up to about 0.47 in) and are usually green, blue and metallic. Look for these features:

• Metallic green, blue or bronze body
• Larger and louder than a house fly
• Often appears suddenly in large numbers indoors

They are most often confused with house fly and horse fly. See the full blow fly profile for side-by-side details.

Why you have blow flies

Blow Flies come indoors looking for food, water, warmth or shelter. Gaps around doors, windows, pipes and utility lines give them easy ways in. Clutter, leaks and food left out let a small problem grow into an infestation. They are most active in spring, summer and fall, so expect to see more of them then.

When you'll see blow flies

Blow Flies are most active in spring, summer and fall. In spring, overwintering adults become active and many species lay their first eggs. Summer heat speeds up development, so populations can grow quickly. In fall, many bugs look for shelter, and some move toward or into buildings.

Typical places to check: kitchen and indoors, anywhere.

Step-by-step: getting rid of blow flies

Step 1: Search for

Search for and remove any dead animal, then clean the area. Keep notes on where you still see activity so you can focus your effort.

Step 2: Double-bag meat scraps

Double-bag meat scraps and take trash out often. This is the step most people skip, and it is the one that makes the biggest difference.

Step 3: Seal openings to attics

Seal openings to attics and chimneys. Keep notes on where you still see activity so you can focus your effort.

Natural and low-toxicity options

These methods work well alongside the steps above and keep chemical use to a minimum:

• Vacuum insects and egg cases, then empty the canister outdoors right away.
• Wipe surfaces with soapy water to remove scent trails and residue.
• Place sticky traps to find out where activity is highest.
• Run a dehumidifier where damp areas attract them.

If you do use a pesticide, choose one labeled for this pest and the place you're treating, and follow the label exactly. The label is the law.

When to call a professional

Call a licensed pest control company if you still see blow flies after three to four weeks of steady effort, if they are spreading to several rooms, or if you share walls with neighbors who have the same problem.

How to keep blow flies from coming back

• Seal cracks and gaps with caulk and install door sweeps.
• Store food in sealed containers and take out trash often.
• Fix leaky pipes and faucets and keep basements dry.
• Trim shrubs and branches so they don't touch the house.
• Keep firewood, mulch and debris away from the foundation.

Safety notes

Blow flies don't bite but can carry bacteria from rotting material.

Keep children and pets away from any traps, baits or treated areas.

About flies & mosquitoes

The blow fly is one of the flies & mosquitoes. Flies have only one pair of working wings; the second pair is reduced to small balancing knobs called halteres. They go through complete metamorphosis, and the larvae, called maggots, need moist organic material such as garbage, soil, drain film or standing water.

Fly problems are almost always breeding-site problems. Finding and removing the moist material where larvae develop works far better than swatting adults.

Frequently asked questions