A couple of weeks ago I started noticing a large number of flies in my campus office. They are a mild nuisance as they get trapped between my blinds and windows and the buzzing noise is distracting. The large number of fly corpses is also gross, but I’m a biologist, so I’m taking it in stride.
Due to the fact that I’m a nerd, I’ve been attempting to solve the mystery of where these flies are coming from and what type of fly is in my office. I was quickly able to rule out the blowfly, which means that my fear of a rotting animal in my ceiling is likely unfounded. So it’s a toss up between the common house fly and the cluster fly. Based on the fact that the flies are pretty sluggish and have golden hairs on the thorax my best guest is that they are cluster flies.
Cluster flies feed on earthworms as maggots and move into buildings when it comes time to hibernate. I’m guessing that because September was so warm, it’s only recently that the flies have started to move into my building and invade my office. I’m guessing I’ll see a second wave when they all wake up in the spring.