Fireflies and

Fireflies and Glow-worms: An Introduction


FIREFLIES & GLOW-WORMS have dazzled mankind for thousands of years. These small animals were discussed not merely by the scientist but frequently appeared in literature, prose and poetry, and also played a prominent part in folklore and medicinal remedies. They were probably the first luminescent animal to have been recorded in literature. As far back as 1500-1000 B.C. fireflies and glow-worms make an appearance in the Chinese Book of Odes (Shih Ching).

Fireflies and glow-worms are neither flies nor worms but are in fact beetles. Unlike the majority of other beetles they have the remarkable ability to emit light known as bioluminescence from specialised regions of their body known referred to as light organs or lanterns. Fireflies and glow-worms mostly light up after the sun goes down and these displays can range from a continuous steady glow to strong flashes or pulses lasting less than a second.

For a long time it was speculated that this light emission in adults was the basis for sexual attraction. For fireflies that produce pulses or flashes minute differences in the pattern can be observed between different species so not only does the light display provide a way of attracting a mate from a long distance but it also attracts the correct mate. In some cases this process of attraction is amplified a hundred fold and resulting in a marvellous phenomenon known as synchronised flashing. In certain parts of the world fireflies congregate in trees and begin to flash in time to each other producing a Christmas tree effect. Such displays are hard to miss for both the firefly and the entomologist.

There is considerable confusion surrounding vernacular terms for bioluminescent beetles. This confusion primarily relates to the continental differences in the use of the term 'glow-worm'. In the North America all members of the beetle family Lampyridae are referred to as fireflies or lightningbugs; 'glow-worm' refers to members of the bioluminescent beetle family Phengodidae, also commonly known as railroad worms. However in the States 'glow-worm' is additionally used in connection with certain species of fungoidal gnats (Diptera, i.e flies) famous in New Zealand and Australia for illuminating subterranean caverns.

In Europe 'glow-worm' refers to the lampyrid species which have flightless larviform females. In addition it is used to describe the larvae of Lampyridae. In this website I will use glow-worm and firefly to distinguish between flightless and flighted species of the Lampyridae and when referring to all species I will use the diminutive term lampyrid.