BLINDED BY THE LIGHT

On balmy evenings, amorous beetles put on a spellbinding show in North American forests

- Mike Dilger's

Described by poet David McCord as “little lanterns sailing by, like stars across a mimic sky”, the sight of fireflies lighting up the night as they search for mates is a shining example of a wildlife spectacle.

Fireflies are also known as ‘lightning bugs’ and ‘glow worms’, but these alternative names are as taxonomically illiterate as ‘fireflies’, since these illuminating insects are in fact beetles from the family Lampyridae. More than 2,000 species are currently described and many of them are capable of emitting light, with aerial displays recorded from Mexico to Malaysia and Japan to the Phillippines. However, fireflies are perhaps best known and have been most comprehensively studied in the USA.

The magic trick of bioluminescence is, of course, not confined to beetles, with certain fungi, jellyfish, shrimps and plankton also capable of manufacturing light, at least in some capacity. The beetles’ bioluminescence is created by a highly efficient chemical reaction that results in the release of light with little or no emission of heat. Referred to as a ‘cold light’, this contrasts with incandescent light bulbs, where 90 per cent of the energy used to create the light is in fact wasted as heat.

Did you know? 

Adult fireflies are 5mm to 25mm in length. Unlike most beetles, which have hardened forewings (called elytra), their forewings are soft and flexible.