Be creative. Don't rely on the lightning bug theme. This was just an idea. Perhaps a dragon that breathes light instead of fire, or an owl with LED light eyes (since owls are the animal kingdom's best night vision creature). Or go non-animal with a sun that creates light with an LED instead of from nuclear fusion.
For these versions, the green color is good. He looks happy and jovial, that's good. The tail, which would be the LED, should look a little more like an LED, but a cartoon version. You can get an idea of what LEDs look like from our website at www.acriche.com. This guy looks a little too "wormy". And without the legs looks best.
Could you demonstrate the light from the tail with some "rays"? But not to overpower the design, only to emphasize that it is light.