If you're in Towns 1, the reason is the time of day. If you go to towns during sunrise/sunset you'll find mostly red bugs, at night time mostly blue ones and fireflies. Green, black, brown bugs, and yellow butterflies etc are usually around in the day time.
If you're in Towns 2, I don't think they've implemented all the bugs yet. I've never seen any red bugs there for example.
If you're in Towns 1, the reason is the time of day. If you go to towns during sunrise/sunset you'll find mostly red bugs, at night time mostly blue ones and fireflies. Green, black, brown bugs, and yellow butterflies etc are usually around in the day time.
If you're in Towns 2, I don't think they've implemented all the bugs yet. I've never seen any red bugs there for example.