Often in fiction, fairy creatures, fireflies or other magical insects get depicted as simple little points of light rather than going for a full design for something so tiny we'll never get a good look at it. The obvious inspiration is fireflies. It's funny how fireflies often end up behaving in usual and rather magical ways. In a way, it's an example of the connection between light and magic. Do not confuse with By the Lights of Their Eyes; this trope is about Energy Beings or Faceless Masses that may or may not sparkle. See also Ghost Lights.