The light shows created by myriads of flashing fireflies against a black night sky of summer have been fascinating mankind for ages. The nearly 2,000 species of fireflies worldwide inhabit every continent except Antarctica.
The firefly, or lightning bug, isn’t a fly at all, but a beetle from the family Lampyridae, which in Latin means “shining fire.” Photocytes, or light cells, in the insect’s abdomen are where the glow is produced. The light is the result of a chemical reaction known as bioluminescence that occurs when two substances, luciferin and luciferase, react with one another when exposed to oxygen. The firefly regulates the flow of oxygen into its abdomen to turn its taillight on or off. This cold, living light is almost 100 percent efficient, losing only a fraction of its energy to heat. By comparison, a standard incandescent light bulb is less than 10 percent efficient.
The main idea of a firefly’s light show is to attract a mate. The males fly around while turning their lights on and off, hoping to get the attention of a flightless female waiting in low vegetation. If a female is impressed by a male’s flickering, she will flash back a response to the twilight glow. Each species of firefly has its own unique flash that is characteristic of its sex and species. Carnivorous females of the genus Photuris are known to entomologists as femmes fatales. These fireflies mimic the flashes of females of other firefly genera; the unsuspecting courting male flies in expecting romance and is promptly eaten.
These creatures of the night are truly a gardener’s friend. Firefly larvae eat countless numbers of snails, slugs, and cutworms, and devour the larvae of many other insect pests.
Over the past several years, the number of firefly sightings has declined. Some think that this could be due to increased pesticide use or loss of habitat from urban sprawl. Excess lighting from shopping centers and streetlights may also be interfering with firefly mating flashes. To help these bright little insect friends, limit pesticide use, especially on lawns; keep outdoor lighting to a minimum; and plant a few shrubs and low trees to provide daytime shelter. You could be rewarded with many delightful, and enlightening, summer guests.