How to get rid of and prevent cluster flies

Cluster flies, or attic flies, are typically brown to greyish brown flies and similar in size, shape and behavior to the blowfly. Larger and slower than house flies, cluster flies can be a nuisance around homes, often getting inside and laying eggs. This  causes cluster flies  to keep coming back just when you think you may have gotten rid of them.

Western Exterminator is the expert in fly control. We know that flies in homes and anywhere in a business can give the appearance of the property being unclean. We can help you get rid of cluster flies and offer services to ensure they do not come back. Contact your local Western Exterminator office today.

How long do cluster flies stay?

Cluster flies can stay inside walls, attics, and other quiet areas for weeks or even months. Most show up in early fall and stay hidden through the winter. They often come out again in late summer or on warm days, especially if your heating turns on. Since they can hibernate in large groups, it might seem like a cluster fly infestation appears suddenly.

They tend to return to the same spots every year. If they’ve gotten inside once, they’ll likely do it again unless you seal up the entry points. This isn’t just a problem for homes; businesses can also experience cluster flies gathering in false ceilings, wall voids, or storage areas.

Are cluster flies dangerous?

Houseflies and blowflies are risky to cooking surfaces because of the nature of what they like to land on, and you might think cluster flies pose the same risk. When you see so many of these large, slow-moving flies, you might think there is something rotten, or they are contaminating the same places.

The good news is, this is not the case. Yes, cluster flies are annoying when they start slowly buzzing around your head, but they are not considered dirty or a risk. Cluster flies are parasitic, laying eggs directly on earthworms. Once the eggs hatch, the larvae feed on the worms. They do not lay eggs in human food and tend not to frequent rotting food or dead animals.

How to remove cluster flies indoors and outdoors

So let’s move on to the key topic: how to get rid of cluster flies. 

The first step is to find out where they’re coming in. They often hide in wall voids, false ceilings, and attics. Outdoors, you might see them gathering in large numbers on sunny walls, especially near vents, soffits, and door frames.

Next, use a vacuum or swatter to remove visible flies, but keep in mind this doesn’t address the root cause. You can use light traps or place sticky traps near windows where the flies tend to gather.

If you're seeing flies in several rooms, or they keep coming back, there may be more going on behind walls or in hidden spaces. In that case, it’s best to reach out to us; our pest control technicians can help treat both the visible flies and the places where they hide.

What’s the most effective cluster fly treatment?

One of the most effective ways to get rid of cluster flies is to use a residual insecticide inside cracks and crevices where flies rest or enter the property. These include areas around baseboards, light fixtures, and inside crevices and gaps in attics or crawl spaces. For outside treatments, it's important to spray around known entry points.

DIY sprays may help in the short term, but they rarely reach all the places flies hide. Since these flies often invade hard-to-reach areas, professional pest control is often needed to treat the full cluster fly infestation. 

At Western Exterminator, we provide both residential and commercial pest control services to deal with flies and a wide range of other pests.

Natural ways to get rid of cluster flies

Once cluster flies get into your home or property, there is not much you can do but try to trap them or kill them. It's the eggs you need to worry about and then you need to work to prevent cluster flies from returning.

Some of the things you can do to help get rid of cluster flies and stop them from coming back include:

• Vacuuming - home and property owners who make sure to keep their carpets and floors clean can vacuum up the flies themselves, but also any larvae or eggs present.
• Getting rid of debris around the yard - cluster flies in winter are often found on the sides of buildings or within wooden structures around the yard. If you have any old or abandoned buildings on your property, or debris and junk in your yard, you may have a place where cluster flies will breed.
• Sealing up the house - cluster flies like to lay eggs in attics and between the walls. Make sure the roof shingles are in good order and replace any that are broken. Seal up holes around your home and make sure windows have screens and that the screens are free of holes.
• Seal up food - particularly sweets. Cluster flies will land on food and they love sweet things. If you seal these things up you can keep flies away.
• Get rid of standing water - because cluster flies love to land in still water in order to survive. Doing this also keeps away mosquitoes, by the way, so any standing water around your property is good to get rid of.

Contact Western Exterminator for cluster fly control

Western Exterminator technicians know the difference between blowflies, house flies, and cluster flies. We know where they get in and where these flies like to hide. Our trained technicians can track down the places the cluster flies are hiding and where they may have laid eggs. We offer treatment programs to get rid of cluster flies inside your home and property. We also can provide you with solutions you can consider to help prevent flies from coming back.

If you are dealing with too many cluster flies around your home, contact your local Western Exterminator office. We will do a property inspection and offer you the cluster fly removal solutions to help get rid of the pests during all life stages and prevent their return.

Frequently asked questions