Cluster Flies: Tackling this Wintertime Problem Early

By Allison Clayton

This winter, you may spot flies gathering in your attic or upstairs windows. While harmless to humans, cluster flies can become a nuisance during colder months as they flock indoors for shelter. 

If you’re curious about keeping these pests out of your home, we have you covered. Here are some tips and tricks to keep cluster flies from invading your residence.

Why are Cluster Flies in my Home?

During the winter months, cluster flies will head into warm areas to escape the cold. These pests may enter through small cracks, openings in windows and doors, or baseboards. 

They will hibernate in your home during the winter, typically within attics or walls. You’ll notice the flies emerge as the temperature outside gets warmer.

At times, if the winter temperature increases, you may see these pests before the beginning of spring. As they sense their environment heating up, they will head toward sources of light and warmth like windows and doors. 

As explained by their name, these insects will cluster together, trying to find their way outside. 

Are Cluster Flies Dangerous?

Unlike other fly species, cluster flies are harmless. They will not usually interfere with anything in your home and will hibernate in unseen areas until the end of winter. 

While some insects prolifically reproduce when inside your home, you won’t have to worry about cluster flies. They will not create any young while in your home as they typically breed outside during the spring and summer months. 

Cluster flies do not bite, so you shouldn’t be too concerned if you spot them in your home. They don’t spread diseases or swarm around your food and trash like other fly species. 

Besides being a visual nuisance, they won’t cause you any harm. However, you may feel uneasy about the presence of these flies in your home. Spotting these pests covering your windows and doors is an unnerving sight.

Is this a Cluster Fly or a Housefly? 

Most flies look the same, and these two insects are no different. It can be difficult to distinguish between the two, especially if you’re unsure of what to expect. 

House flies are usually smaller than cluster flies. If you see anything larger than ¼ of an inch, you could be looking at a cluster fly. 

If you have flies in your home, consider the time of year you see these pests. If you’re seeing flies at the beginning of spring, you probably have cluster flies in your home. 

Cluster flies are also much darker than house flies. While you may not want to get too close to these little pests, take a good look at the insect to see what fly is invading your home. 

Cluster Flies Pest Control Tips

If you’re looking to pest-proof your home before the winter or want some tips to get cluster flies out of your home now, we can help. Here is some advice to make your home pest-free. 

Don’t Give Cluster Flies Access to Your Home

Preventing an infestation starts by stopping these little pests in their tracks. You need to cut off any entry point before they have a chance to enter your home. 

Repair any broken screens on your doors or windows. If you keep these open during warm fall days, cluster flies could come inside in anticipation of the winter chill. 

Look around for any holes in your roof as well. Cluster flies will hide in attics or crawl spaces, and hard-to-reach gaps will make it easier for the pests to get inside. 

Cover up any small cracks or crevices in your home with plaster, mortar, spackle, or another material of your choice. If you believe cluster flies are entering through vents or other places you can’t easily cover, try focusing on other prevention methods to keep them out. 

Use Chemical Pesticides 

Besides closing off areas of your home, you can also use sprays and powders to keep your home free of cluster flies. 

Choose a pesticide designed to repel cluster flies. Many indoor fly products will do the trick. If you pick out an all-purpose insect repellent, avoid dispersing the product in areas that could potentially impact other insects. 

Select a residual pesticide that will last through the winter months, and be sure to reapply based on the product’s instructions. If you place this product in areas where the cluster flies may come inside, you could prevent them from entering your home. 

Be careful when spraying a store-bought pesticide in your home, and avoid using chemicals in poorly ventilated rooms. 

If you’re worried about the pesticide damaging the fixtures inside or outside your home, check the product’s instructions before dispersing. 

Controlling Cluster Flies in Your Home

If cluster flies already inhabit your house, you can easily spray them with a pesticide. Keep all children and pets away from these areas until you fully eliminate the cluster flies. 

Be sure to clean up the dead flies to avoid attracting other pests. You can sweep them up or use a vacuum. 

If you’re not interested in spraying pesticides in your home, try using an indoor fly trap to catch the pests flying around. Hang a sticky fly trap from the ceiling, or make your own trap. 

Here’s how you can make a DIY trap:

  • Cut a large soda bottle into two pieces 
  • Add water and sugar to the bottom of the bottle
  • Include honey or syrup if you’re struggling to bait the flies
  • Place the opening of your bottle inside the mixture

The flies should then crawl down the hole and fall into the sugary mixture below. Slowly but surely, you may begin to see your bottle fill up. Frequently clean your bottle to encourage the rest of the flies to enter your trap. 

If you’re interested in learning more about DIY fly traps, check out this article for more great tips.

Contact proof. For Help!

Don’t forget: you can always call a pest control agency to wipe out cluster flies. If you’ve exhausted all of your options but still struggle with the pests, proof. can help!

Contact us today for a quote on our services. Of the over thirty pests we help treat, we can eliminate the pesky flies inside your home.

Call proof. pest control at , or send us a message online.

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