A fly which enters buildings in large numbers while looking for a place to overwinter.
- Pollenia rudis (family Calliphoridae), and the smaller Thaumatomyia notata (family Chloropidae)
More example sentences
- Bluebottles and cluster flies are disgusting little creatures, feeding off rotting food and excrement.
- Face flies and two or three species of cluster flies are often found in large clusters in the same overwintering site.
- Of course, spring is a good time to find earthworms, so the cluster fly is active during this season.
Definition of cluster fly in:
- The US English dictionary