system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do gnats swarm in seemingly random spots in mid air?

I see little gnats in small swarms just flying around in just random spots in the air. Not necessarily over trash or standing water, just in a ball of gnats in the air. What's the reason?
gpt
When they are swarming they are mating. You are basically watching an orgy. When they are done they will go lay their eggs (often on decaying plant matter) and then typically die. Some species are attracted to street lights and the like others are not.