A warm autumn day might cause cluster flies to "bug" you around the house. See how to get rid of cluster flies with these tips.
How To Get Rid of Cluster Flies
Slightly larger than the common house fly, cluster flies are dull gray in color with black markings. They have golden-yellow hairs on the thorax and find their way indoors during the fall as they seek a warm place to overwinter. Often found in wall voids and attics during the fall and winter, they will also cluster around windows for the warmth and light they offer.
Cluster flies may be a nuisance, but they won’t reproduce within your structure and do not carry any diseases. In fact, the only damage you’ll likely see are small dark-colored spots of excrement on windows and walls. Learn more about how to get rid of this benign yet unsightly pest with tips from Danielle Restuccia, Division Technical Services Manager for Orkin’s Northeast Division.
How To Prevent Cluster Flies from Entering Your Home
Many flies, like cluster flies, love the sunlight and warmth, which is often why they buzz against windows. So always make sure your open windows have screens to keep flies from entering. Likewise, don’t leave doors without screens open for long periods of time. To further prevent cluster flies from entering your home, Restuccia recommends you “seal points of entry by filling cracks and gaps around doors, windows and siding [and] and ensure screens in windows and doors fit securely.”
While you’ll find that cluster flies are slow enough to capture and swat, you might be hoping to avoid them altogether. Your best bet is to do a little investigation. Where are they coming from? If they’re on the exterior of your home, you can use exterior insecticides consisting of a synthetic pyrethroid or a neonicotinoid, which you’ll want to hire a licensed pest control professional to apply. It’s important to note, however, that because the application is occurring in a sunny area, which breaks down the insecticide, the effectiveness may decrease after a week.
How To Get Rid of Cluster Flies
“If there are just a few cluster flies buzzing around, you can shoo them out or vacuum them up with a vacuum hose attachment,” Restuccia says.
Other options include hanging sticky fly strips or using a glass jar with sweetened water inside and a perforated lid to trap them. Just be sure you make the holes large enough for the flies to enter and change out the water every day. Keeping food covered is also important. Cluster flies especially love decomposing food and sweets! A contact pyrethrum spray like CB-80, which is approved for indoor use, can help. Spray it lightly, as needed, for contact kill.
To prepare for the next season, you can spray areas where you suspect these pesky flies will cluster. In early summer, be sure all your suspect cracks are sealed up. You can also apply a residual pyrethroid-based insecticide such as Suspend SC or Demon WP on the exterior of the building in late August or early September, right before adult cluster flies show up.
“But if cluster flies become a serious problem, homeowners should call a pest control professional,” Restuccia says.
FAQ
Why are they called “cluster” flies?
Their name is due to their behavior of gathering in groups or ‘clustering’ together, particularly when seeking shelter during cold weather months.
Do cluster flies lay eggs in the house?
No, cluster flies lay their eggs outside in the soil and primarily live outside as well. They only venture inside for a warm environment during cold weather seasons.
About the Expert
- Danielle Restuccia is Division Technical Services Manager for Orkin’s Northeast Division.
