(09-16-2023, 04:40 PM)RobertH Wrote:
I think they're called Cluster Flies.
I've seen them gain access to my home by slipping past window weather stripping, my windows are relatively new and seal well, but the tiniest of gaps they sneak through.
A few years ago I found them under the sill of some older windows, they were nestled together for warmth.
I sealed up as many openings as possible, very few this year.
Cluster Flies
https://extension.colostate.edu/topic-ar...ies-5-618/