This is reply of another postFirefly flashes are part of complex system of insect seduction:
Male firefly flash
Male fireflies in the air use distinctive patterns of flashing and flying to signal to females of their species on the ground.
Female firefly flash
Females then respond with a flash, after a set interval that signals they are of the same species.
Firefly flash light energy source
Nearly 100 percent of the flash's energy given off as light; in standard light bulb, 10 percent of the energy is light and the other 90 percent is given off as heat.
How Firefly flash works
The firefly's light is produced during a chemical reaction. The light emitting organ consists of three layers: Reflector, light cells and Transparent exoskeleton.
Replied Article in Science