What are Fireflies and Glow-worms ?

Glow-worms and fireflies both belong to a special group of luminous beetles (Coleoptera: Lampyridae).

 

  • Their light is produced in specialized cells of their light organs, where a special biochemical reaction takes place.

  • Light produced by organisms is called bioluminescence.

  • Worldwide, there are over 2000 firefly and glow-worm species

  • New species are still being discovered, even today.

  • The difference between fireflies and glow-worms ?

    • fireflies are the winged forms capable of flight

    • glow-worms represent the wingless and thus flightless members of the Family.

  • Many species suffer from habitat loss, pesticides and light pollution. That is why we started Survey projects worldwide​.

A bit confusing is that depending on the location in the world the term glow-worm also refers to other insect groups, : in Europe glow-worms are lampyrids, but in the Americas this name refers to another luminescent beetle group (Phengodidae) and in Australia and New-Zealand it refers to the glowing larvae of fungus gnats, Arachnocampa spp. (Diptera: Keroplatidae). So we have to be careful and distinguish between European, American and Australian glow-worms !

Fireflies and glowworms demonstrate their light displays especially at night. But why do they disclose their presence and why would they make themselves vulnerable to possible enemies?

Well, adult fireflies "speak" with a language of light. Depending on the species it is,

  • either the male that flashes a species-encoded love-call in the hope of getting a flashy answer from a female.

  • in glow-worm species, it is the female that tries to draw the attention of overflying males by a brilliant glow.

  • Also immature stages (larvae, pupae and even eggs) produce light.

  • The light displays are also used to deter enemies, either by frightening or by signalling that they are defended by toxic chemicals or by a bad taste. This last tactic is called bioluminescent aposematism.

Many firefly species have diurnal adults that use "chemical communication" with scents (pheromones) instead of "visual communication" by glows or flashes. The males of such diurnal species often bear larger or elaborate antler-like or plumose antennae and they are often non-luminous as adults. Yet, all known lampyrid species seem to have glowing larvae.

What do they eat?

Firefly larvae are predators and spend several months (tropics), up to one to three years (temperate regions) in order to develop. Most species hunt for snails and slugs, others for earthworms. Some species are less specialised and attack any small and soft invertebrate, or even kin.

 

Adults of most species do not feed and seem to be short lived, from one to several weeks, but some species feed on nectar, plant saps and in the Americas there are even species (e.g. Photuris spp.) that hunt for other fireflies in order to obtain defensive toxins they cannot fully metabolise themselves. The females of such aggressive species even imitate the female flash codes of the other species in order to mislead, attract and devour the males of the better defended species.

Photinus carolinus - (c) Radim Schreiber
Lampyris sardiniae larva, Sardinia (c) R De Cock
Pyrocoelia species, male adult , Shandong prov. - China (c) R. De Cock
Pyrocoelia species, larvae, Wuhan - China  (c) R. De Cock
Pyrocoelia species, larva, Wuhan, China (c) R. De Cock
Pygoluciola qingyu, male adult , Shandong prov. - China (c) dr. Xinhua Fu
Lamprohiza delarouzei, female adult, Aix-n-Provence, France (c) Sascha Grimm
Lamprohiza delarouzei, female adult, Aix-n-Provence, France (c) Sascha Grimm
Nyctophila reichii, female adult, Serra da Estrela, POrtugal (c) R. De Cock
Lampyris noctiluca, adult female
Pyrocoelia species, male adult , Shandong prov. - China (c) R. De Cock
Pyrocoelia species, male adult , Shandong prov. - China (c) R. De Cock

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