system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: how do gnats just "appear" in my house overnight?
gpt
Could be fruit flies. They lay their eggs on soft spots on fruit, which you may then take into your home, where they hatch. If you have a lot of fruit about, they may then subsequently lay more eggs on more of your fruit, and you wind up with a pest.