Cluster Flies vs. Household Pests: How to Identify and Differentiate

A fly isn’t just a fly—there are over 18,000 different types of flies in the U.S, each with its own habits and potential threats. But they do have some things in common: they all tend to have short lifespans and they are all experts at being nuisances to homeowners while they’re alive. Let’s dig into cluster flies and learn how to tell them apart from other common flies and what to do if you find them in your home.

What are Cluster Flies?

Cluster flies, scientifically known as Pollenia rudis, are a common species belonging to the family Calliphoridae. They are often mistaken for common house flies but have distinct characteristics and behaviors.

As temperatures drop, cluster flies seek warm, sheltered areas to overwinter, like your home. Cluster flies, named for their tendency to gather in large numbers, often invade attics and wall voids, making them a common yet elusive household pest.

Adult cluster flies feed on flower nectar and other organic materials. They are not attracted to human food or waste like other flies, but they’ll still cause damage in your home and keep you on edge with a continuous buzz.

Cluster Flies vs. House Flies and Other Flies

Cluster flies look most similar to house flies, but there are 4 main differences:

1. Cluster flies are larger in size than house flies
2. Cluster flies are darker in color than house flies
3. They are more sluggish in movement than house flies
4. They don’t have black stripes on their thorax like house flies

Here is a helpful chart noting the most common flies homeowners in New England deal with and how to identify them.

How to Prevent Cluster Flies

Now that you know what cluster flies are, let’s explore how to ensure you never see them in your home. 

• Seal Cracks Around Windows and Doors: Use caulk to seal cracks around windows and doors and make sure your window and door screens are intact and free of holes.  
• Install Attic Vents: Placing fine mesh screens over attic and roof vents can help prevent cluster flies from entering.   
• Do Exterior Maintenance: Fix any damage to your home that could allow entry by cluster flies and trim back vegetation.  
• Get Exterior Prevention Treatments: Professional pest control companies, like Ford’s Hometown Services, can apply an exterior treatment on your home to create a barrier and stop cluster flies from gaining entry. It’s part of our Fall Invaders Program. 

Cluster Fly Control Tips 

If cluster flies have made it into your home, it’s important to take action. Here are some tips: 

• Use a vacuum or shop vac to suck up the flies. They're naturally slow moving, so it’s easy to catch them.  
• In attics, consider using an insect light trap to catch the cluster flies as they emerge from hibernation.  
• Call the professionals at Ford’s Hometown Services to apply targeted treatments.