Cluster Fly
Easy DIY
Identification
Slow-moving, dark gray flies that seek shelter indoors in large numbers in fall, clustering in attics and wall voids to overwinter.
Can I DIY this?
Easy DIYYou can handle this one yourself.
With the right product and a little patience, most homeowners take care of this pest on their own. Follow the treatment guide, read the product label, and you're set.
Recommended products
Syngenta Demand CS Insecticide, 8ozFall exterior barrier on sunny wallsControl Solutions D-Fense Dust Insecticide, 1lbDust attic & void entry pointsStryker 54 Contact Insect Aerosol, 15 ozKnockdown for indoor emergersSome links may be affiliate links. Buggsy may earn a commission at no extra cost to you. Always follow the product label.
- Find and eliminate the breeding source — garbage, drains, manure, or rotting produce. This matters more than any spray.
- Set out fly bait away from food prep areas.
- Apply a residual spray to the surfaces flies rest on, like walls, ceilings near light fixtures, and eaves.
- Add fly lights or traps near doors and other entry points to catch stragglers.
- Repair screens and seal gaps to keep new flies from getting in.
- Reapply per the label — once the breeding source is gone, most infestations don't come back.
Wear long pants, a long-sleeved shirt, closed-toe shoes with socks, chemical-resistant gloves, and goggles. Add a respirator if the label calls for it or ventilation is poor.