How to Identify Cluster Flies

What Do Cluster Flies Look Like?

Cluster flies, also known as attic flies, are 8 to 10 mm in length. They are dark gray with light and dark markings on their abdomen. The thorax is covered in short, golden-yellow hairs. Cluster flies tend to fly much slower than house flies, making them somewhat easy to swat with a fly swatter. They have six legs, large red compound eyes, and one pair of translucent wings. The cluster fly’s wormlike larvae (maggots) are cream-colored and elongated in shape.

What are the Signs of a Cluster Fly Infestation?

Cluster flies enter houses in the fall to hibernate during the winter. These flies will cluster in large groups in dark, secluded places, such as wall cavities, attics, and false ceilings. In spring, cluster flies become active and often end up inside the living spaces of homes, becoming a nuisance when attempting to leave their hibernation site. In winter, they are mostly dormant. However, on warm sunny days, cluster flies will congregate around windows.
Dead Flies on Window Sill

Cluster Fly Control in Milwaukee, WI

Advanced Wildlife and Pest Control offers professional fly control services in Milwaukee and southeastern Wisconsin. Our certified pest exterminators provide reliable, long-lasting solutions to eliminate nuisance cluster flies for homeowners and businesses. Our targeted pest treatments and recurring maintenance services will ensure your property remains pest-free throughout the year.
Dead Flies on Window Sill

Are Cluster Flies Harmful?

Cluster flies are generally considered a nuisance pest. They do not carry diseases and will not cause extensive damage to your home. However, these pets may leave small dark spots on windows or walls with droppings. Large numbers of cluster flies often congregate around windows and inside ceiling light fixtures, making them a nuisance for homeowners. These flies will leave a stain on fabrics and walls when squished.

How Can I Prevent Cluster Flies?

The following prevention tips will help deter cluster flies from your property.
  • Inspect and repair door and window screens.
  • Seal up cracks around windows, doors, utility pipes, and fascia.

Cluster Fly FAQs

Frequently Asked Questions

Do cluster flies bite?

No, cluster flies do not bite or sting humans. They have sponge-like mouthparts used for sucking. Unlike most fly species, cluster flies do not carry harmful diseases or pathogens.

What is the life cycle of a cluster fly?

Cluster flies undergo a complete metamorphosis from egg to adult. Female cluster flies lay their eggs in the soil in late spring or summer. These eggs hatch within a few days, and the larvae seek out earthworms to feed on. The cluster fly life cycle can take 25 to 40 days from egg to adult. On average, adult cluster flies live for one to three months. However, these flies are overwintering pests and lay dormant for several months before emerging in the spring. Cluster flies do not breed or lay eggs indoors.