On spring evenings you may notice small bright lights flashing and flying erratically through the air, these are fireflies. What makes this little insect so spectacular is bioluminescence – the ability to glow. Tamborine Mountain is home to two famous nocturnal, bioluminescent creatures – fireflies and glow-worms.
The common name of firefly is misleading. Fireflies are actually carnivorous beetles of the family Lampyridae. Although there are some 1700 species worldwide, only 16 have been described from Australia.
This species usually favours damp areas with undergrowth and leaf litter. Eggs, larvae and adults all have luminous qualities, but the adults, particularly the males, emit the strongest light. Larvae use light to deter predators and adults use light to find a mate.
The firefly creates its bioluminescence through a chemical reaction between luciferin (a waste product), luciferase (an enzyme), and a reactant, in fireflies this is adenosine triphosphate (ATP) and oxygen. This chemical reaction produces energy in the form of light. The fireflies are able to regulate the emission of light by controlling the amount of air supplied to their cells through opening an aperture in their body. It is thought that the insects use this light pulsing to communicate. The ability to regulate light emission is dramatically demonstrated by some tropical firefly species, which gather together in large numbers in trees and bushes, and synchronise their flashes in a spectacular light show
The life cycle of the firefly is egg, larvae, and adult. The larvae are terrestrial and live in leaf litter, where they prey upon snails, slugs and earthworms. They can inject toxic digestive enzymes into their prey, which liquefies the flesh, allowing it to be easily consumed. The larvae’s lifespan is not yet known, for our local species it may be approximately one year.
In spring the adult male beetles take flight and flash their light signals as a mating display to the females, who remain on the ground. The females flash back a weaker signal to attract the flying males. Their activity decreases in bright moonlight since the light seems to interfere with their ability to produce and see light signals. The adults only live for a few days; research suggests they survive for about four nights. They do not have mouthparts and so cannot feed. Their short lives mean that it is urgent that they find a mate quickly. Males have large eyes and a visor like structure so they can focus on locating light signals from receptive females.
Unfortunately global firefly populations are dwindling, in some places dramatically. In such a light dependent creature it is not surprising that light pollution is one factor implicated in this decline. On Tamborine Mountain the amount of light pollution from street lights, houses, commercial lighting and bright exterior lights has increased, so turning off a few garden lights in spring may help to keep these enchanting little insects flying.