What are these tiny little flying bugs attracted to light from a lightbulb?

These little bugs are so small they fit through window screens. They aren't mosquito since mosquito cant fit through window screens. They are really small and are usually found flying around in a huge group outside grass areas. They all gather around and near my light and just die there. I see a pile of these bugs all dead inside my lamp. Some are flying around on the ceiling like they are hopping around. I'm sure they're harmless but they are annoying.