JUNE
1988

 

 

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

 

 

 

 

6-30-88

INSECT FLASHERS

West Lafayette, Ind.
No warm July evening would be complete without the flickering lights of fireflies.  Sometimes called lightning bugs, these insects are neither flies nor bugs.  They are beetles that have long amazed scientists and amused children with their ability to produce light.

Although scientists have studied the lighting mechanism of fireflies, it is not completely understood.  However, the idea has been incorporated in the development of chemical light sticks, such as emergency flares.  The light produced by the firefly is a cold light with efficiency in excess of 90 percent.  By comparison an incandescent lamp is about 10 percent efficient, which means about 90 percent of its energy is used for heat.  Sunlight is about 25 percent light and 75 percent heat.

Fireflies produce light from a substance called luciferin.  When luciferin is mixed with oxygen in the presence of an enzyme called luciferase, light is produced.  Both luciferin and luciferase are based on the Latin word Lucifer, meaning “to bring light.”  The same name was given to the angel of light, who fell from grace and became Satan.

Scientific names of fireflies also show an association with light.  For example, one genus is called Lampyris.  Photo is found in the common genus name Photouris and Photinus.  A species within the genus Photinusis named pryalis, which is drawn from the Greek root, pyr, meaning “fire.”

Fireflies flash their lights in various patterns – sort of the Morse Code of the insect world.  The flashing has one purpose:  to attract a mate.  The males fly overhead, advertising with their mobile neon lights for a mate.  Females commonly remain on the vegetation but respond to an attractive male with similar flashing.  When both sexes agree that they are the light of each other's lives, the male lands near the female.  Then they “turn out lights” and proceed with the firefly mating game.

Most of the flashing activity of fireflies occurs in the early evening hours, beginning at dusk.  By midnight, most of the outbursts of miniature lightning have subsided for another day.    

Fireflies are predators, both in the immature and the adult stages.  They consume slugs, snails and other insects.  This food-procuring activity takes a strange twist in one firefly species.  The female mimics the flashing pattern of males of other species of fireflies.  When the lovestruck male lands by the “femme fatale” of the insect world.

Could it be that even among the beautiful and graceful fireflies there is a need for truth in advertising?

 

Writer: Tom Turpin
Editor: Olivia Maddox