The firefly was desgnated the official state insect of Tennessee in 1975. A small, unremarkable beetle by day, the firefly transforms midsummer nights into a fairyland of tiny, brilliant twinkling lights - a wonder of nature. Commonly called "lightning bug." The most familiar species of firefly in Tennessee is Photinus pyralls.

The firefly produces light through an efficient chemical reaction using special photic organs, with very little heat given off as wasted energy. One or both sexes use species-specific flash patterns to attract members of the opposite sex (though not all firefly species are bioluminescent as adults). These signals range from a continuous glow, to discrete single flashes, to "flash-trains" composed of multi-pulsed flashes.

Source:

State Symbols: TN Dept. of Education
The Firefly Files: Ohio State U

Links:

Illustrations of Larvae, Pupae, and Adults : U of Florida
Coleoptera: Lampyridae: Common Insects, U of Florida
State Insects - 50 States List