How to Kill House Flies

House flies can spread disease and multiply before you know it. Here's how to stop an infestation.

It happens to the best of us. You’re tired from a long day of hosting a summer party, and you forget to put a few leftovers away before going to bed. The next morning, you walk into the kitchen to find a buzzing cloud of house flies helping themselves to the food

Quick Guide

Understand the Attraction: Learn why house flies are drawn indoors—typically seeking food sources like leftovers and warm, moist places to lay eggs.
Effective Killing Methods: Discover a two-pronged approach using contact sprays for immediate control and baits or traps (like light or sticky traps) to catch lingering pests.
Prevent Future Infestations: Get actionable tips on sealing entry points like cracks and screens to stop flies before they get inside.
Create a Protective Barrier: Learn how to apply an indoor insect barrier around your home's perimeter to deter flies and other insects from entering.

While they are one of the most common pests, house flies are certainly not harmless. Because they can spread filth and disease, it is important to take control of the situation quickly. Here is what you need to know about killing flies indoors and keeping them from coming back.

Why House Flies Come Indoors

To solve the problem, it helps to understand what draws them in. House flies are constantly on the lookout for two things: food and a warm place to lay their eggs.

The life cycle of a house fly is short—ranging from 14 to 25 days—but they move fast. They look for moist, warm areas to lay eggs, which can hatch into larvae (maggots) in as little as 12 hours. These maggots feed on their surroundings for a few days before emerging as adult house flies.

Indoors, your home can offer a buffet of food sources, including uncovered trash, pet food, and kitchen leftovers. Since they fly, it’s easy for them to slip inside while you’re carrying in groceries or enjoying a breeze through an open door.

What Kills House Flies?

When you have an infestation, you want a solution that works fast. The best way to kill house flies involves a combination of direct control and strategic baits.

Spot-treat with a fly spray

For immediate results, the simplest method is to use a spray to kill flies on contact. Look for an insect control product specifically labeled for house flies and apply it directly when you see them. Always follow the label directions carefully.

Set out traps

Sprays are excellent for the flies you can see, but for the ones you can't, a trap is your best ally. A plug-in light trap uses blue light to draw flies away from main living areas, while more traditional sticky traps work well near potted plants. This helps ensure you catch any stragglers that could restart the cycle.

Use an indoor fogger

If you are facing a heavy infestation that sprays and traps can't handle alone, you might need to release a fogger. These fill the room with a fine mist to control flies on contact. Always be sure to follow the label directions carefully, specifically regarding vacating the area and ventilating the room afterwards.

How to Keep House Flies Out of Your Home

Once you have handled the immediate issue, the next step is prevention. Learning how to get rid of house flies indoors for good requires a few simple changes to your routine and home maintenance.

Clean up common attractants

The first step to preventing a house fly infestation is to remove their food source.

Put food items away and thoroughly clean floors and countertops, especially after cooking or entertaining.
Keep garbage cans clean and lids tightly closed.
Keep your landscape tidy and store yard waste or woodpiles away from your exterior walls.

Seal up entry points

House flies are small and can enter through tiny cracks. Inspect your home to make sure they can't get in:

Check that doors and windows are properly sealed with weather stripping.
Inspect door and window screens for tears and repair or replace them as needed.
Do a quick look around your property for other potential entry points, like gaps around pipes, and seal them up.

Create a bug barrier

You can stop flies before they even make it inside. Apply an insect barrier around your home’s perimeter (kitchens, bathrooms, doors, and windows) to create a shield that deters flies—and other listed insects—from entering.

Treat the source outdoors

To help stop them at the source, you can treat your lawn and landscape with an insect killer labeled for house flies. This controls insects in your yard before they have a chance to find their way indoors.

Keeping house flies out is easier than it might seem. By sealing up entry points, removing food sources, and using the right control products, you can get back to enjoying a fly-free home.