DIY Guides How To Get Rid Of Cluster Flies – Quick & Easy Tips

How To Get Rid Of Cluster Flies – Quick & Easy Tips

Learn how to get rid of cluster flies with our short but helpful guide that discusses the use a fly swatter, caulking outside of your house, and a cluster buster fly trap.

This article seeks to solve the tricky little riddle of how to get rid of cluster flies.  

More importantly, we’d like to equip you with the knowledge to keep these nasty little colonizers out of your home. Just like drain flies, they are noisy, dirty, can contaminate your food and even cause sickness.

So check out our guide to getting rid of cluster flies, to end the nuisance of this pest once and for all.

Let’s begin.

Use the Fly Swatter – Cluster Flies are Slow. 

Macro shot of a cluster fly

Sometimes the best solutions are simple ones, and this happens to be one of those times.  Once in your home, the best method for removing cluster flies is to use a fly swatter.  


Because they are ridiculously slow, at least as far as flies are concerned.  These lazy house flies also tend to cluster (ergo “cluster fly”) around and upon windows, especially windows that are receiving sunlight or warmth from the sun.  For this reason, swatting them shouldn’t be much of an issue.  

Swat, and clean the glass or sill with a wet paper towel and/or Windex.  Done.  Now, if you happen to have a cluster of cluster flies clustering on your window curtains, you might want to consider NOT squishing them into the fabric of the curtain as this will leave their guts on it. Wait for them to move, or use a wet/dry vac and suck them suckers up.

Let’s move on.  

Try the Cluster Buster

If you are willing to spend some money on fly traps there are an array of fly traps out there. However, like a turd on the wall, they tend to be conspicuously ugly when it comes to home decor.   

One more discreet and relatively cheap fly trap that we would recommend is the “Cluster Buster” produced by the people at The Bug Clinic.

This particular trap fits on the corner of your window, is non-toxic and is relatively inconspicuous.  You can purchase the Cluster Buster from a variety of retailers, including Gardener’s Supply Company for about 25 dollars.  

With all this said, the best way of how to get rid of cluster flies is to prevent them from entering your home in the first place.  This in turn begs the question:

Why are They in My Home?

Here’s how and why cluster flies get into your house:  

Although homeowners usually find them in their house in the kitchen and loft areas during the summer months, those cluster flies make their debut in the cool of the previous fall.  They “overwinter” in your home and come out in the summer in a confused attempt to go back outside.  

Wide angle shot of a cluster fly on a bright green leaf

If you’re wondering how this applies to how to get rid of cluster flies, here’s how:  Knowing when they come to your home better prepares you for future defense.  

Prevention is by far the best answer for how to get rid of cluster flies.  The United States Department of Agriculture’s Cooperative Extension is a good source to check with to find out when cluster flies typically come to your immediate region in search of shelter.  

Will they Infest My Home? 

Here’s some good news:  The college of agricultural sciences at Penn State confirms that cluster flies, although a nuisance, do NOT reproduce inside your home.  They “overwinter” in your home and then become active in the early summer, crawling out of wall voids, attics, and other crevices around your home in a confused attempt to go back outside.  

This is good news for you.  Why? Because it means that the threat of infestation is dramatically reduced.  

Every year, they basically have to rely on a new group to enter your home from the outside.  For this reason, as we said earlier, the BEST way that we know how to get rid of cluster flies is to prevent them from entering your home.  Here’s how: 

Keep Them Out with Caulk. 

Consider re-caulking the seams around your exterior windows, doors, siding, utility pipes, behind chimneys, and underneath the fascia.  Good quality silicone or silicone-latex caulk will do the trick.  

Cracks around windows, doors, siding, utility pipes, behind chimneys, and underneath the fascia and other openings should be sealed with good quality silicone or silicone-latex caulk.  

It’s cheap and relatively easy to apply (click here for a brief video tutorial from the good people at Ace Hardware).  Damaged screens on doors and windows should also be repaired or replaced.

Sprays…Not recommended, Especially Inside the House.

Spraying has several drawbacks, especially if it’s not made of natural ingredients.  One drawback is that you have to spray every single year, which is annoying.  Furthermore, timing for the spray is crucial.  Because insecticides are broken down by sunlight, the residual effect of the material will be greatly decreased and may not kill the flies much beyond several days or a week.

Therefore, you have to apply the stuff just before the cluster flies show up.  Too early and the insecticide doesn’t work, too late and the cluster flies have already made their way in.  After flies have gained access to attics and wall voids, then just forget about it. Natural repellents like Lemon Spray will work on other bugs, but not on cluster flies. This means you’ll likely have to use hard pesticides only, which aren’t good for people or household pets.

 It is not advisable to use an insecticide within structures after the flies have gained access to the wall voids or attic areas. Although insecticidal dust treatments to these voids may kill thousands of flies, there is the possibility that carpet beetles will feed on the dead insects and subsequently attack woolens, stored dry goods or other natural products in the home.

Although aerosol-type pyrethrum foggers will kill cluster flies that have amassed in attic areas, it will not prevent flies from emerging from wall voids. For this reason use of these materials is not considered a good solution to long-term management of the problem. Spray insecticides, directed into cracks and crevices, will not prevent the flies from emerging and is not a viable or recommended treatment.

Wrapping Up

To sum things up, the most effective treatment is to prevent them from entering your house by sealing all of your exterior cracks and crevices.  

If they’re inside your house, keep it simple and use a fly swatter.  The use of insecticides is neither necessary nor recommended.  Good Luck!

Managing Editor & CEO Jack has been writing as a contractor and for businesses for over 10 years. He owns his own home, and has been doing his own pest control since he bought his first house.

Leave a Comment