June 4, 1999

    Fireflies

In daylight, fireflies, also known as lightning bugs, are drab little creatures which are seldom noticed.  But when they perform their amazing act of lighting up, they give a special magic to warm summer nights and seem anything but drab.  Sometimes an entire field, lawn, or forest edge will be twinkling with hundreds of these little "lanterns."  The darkness comes alive with the mellow light from these soft-bodied beetles.  Far into the night the moving specks are seen.  We ordinarily see these tiny lights in the dark from late May into July.

So why does a firefly light up?  Simply because the flashing is a recognition signal enabling the sexes to find each other.  Each firefly species has a characteristic flashing rhythm, and an expert observer can identify various species by the length of the flashes and interval between flashes.

Fireflies have segments near the ends of their abdomens which enable them to produce light.  A special organ in the firefly's body produces a protein called luciferin.  An enzyme called luciferinase is also present.  When the insect draws air into its body the luciferin and oxygen are mixed in the presence of the luciferinase.  As the luciferin molecules burn up, they produce the cold and silent light flash.  There are no infrared or ultraviolet rays in the firefly's light.  The light from a fluorescent lamp most closely resembles the firefly light.