Bug FAQCommon Cluster Fly
Pollenia rudis · Order: Diptera · Family: Polleniidae
Also called: Cluster Fly, Awkward Clusterfly
Source: Wikipedia
The common cluster fly is a dark gray fly with a checkered black and silvery-black abdomen; newly emerged adults have golden hairs on the thorax that may fade with age. Adults are about 9.5 to 12.7 mm long, feed on organic matter and earthworms, and seek shelter in homes in large numbers in late summer or early autumn.
Source: Wikipedia
How to recognize it
Newly emerged flies have many golden hairs on the thorax, which may be lost as they age.
Source: Wikipedia
Size
They measure roughly 9.5 to 12.7 mm (about 3/8 to 1/2 inch) in length.
Source: Wikipedia
Is it a pest in the house?
They are most commonly known as a household nuisance. Although troublesome to owners, they do not cause true damage to structures, textiles, food, or humans.
Source: Wikipedia
How to get rid of it
Seal all exterior cracks and openings to keep them from entering the house. Professional extermination is the most reliable way to eliminate an infestation.
Source: Wikipedia
Where it lives
In summer they are found in fields and open areas. In autumn and winter they overwinter inside attics or lofts.
Source: Wikipedia
What it eats
Earthworms are a major food source for the larvae. Adult flies are mostly herbivorous, feeding on various organic matter.
Source: Wikipedia
When you see it
They enter homes in large numbers in late summer or early autumn to shelter for winter. During sunny summer days they are easy to spot outdoors.
Source: Wikipedia
Lookalikes
They resemble other Pollenia species such as P. pallida and P. dasylpoda.
Source: Wikipedia
Where it is found in the US
Recorded in 29 of 51 states and DC. Most records: California, Hawaii, Virginia, Montana, Washington, Illinois, Tennessee, Missouri.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Status: native in North America; native in Canada. Source: iNaturalist
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
How can I prevent cluster flies from entering my house?
Seal all exterior cracks and openings.
Source: Wikipedia
How do I get rid of a cluster fly infestation?
Professional extermination is the most reliable method.
Source: Wikipedia
When do cluster flies usually appear inside homes?
They typically enter homes in large numbers in late summer or early autumn.
Source: Wikipedia
What do cluster flies look like?
They are dark gray with a checkered black and silvery-black abdomen, and newly emerged adults have golden hairs on the thorax.
Source: Wikipedia
Same family (Polleniidae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Pollenia_rudis
Look it up elsewhere: GBIF · iNaturalist · BugGuide · ITIS · Wikipedia
Text written 2026-10-23 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-22.