Belgian biologist Philippe Kok has found that larvae of a firefly species in South-America shifted their diet to a small toad that is supposed to be their predator. Interestingly, the larvae have stopped glowing. In this way, they can better ambush the toad.

Do you have this romantic view of glowing fireflies enchanting your summer nights with their unceasing ballet? This story might make you change your mind. Firefly larvae are much less romantic than the adults, being venomous and voracious predators that usually feed on snails, slugs and other soft-bodied invertebrates.

Predator Becomes Prey

A team of scientists led by Philippe JR Kok (VUB, Royal Belgian Institute of Natural Sciences) reports in Current Biology on a very rare role reversal predation: the larva of an unknown firefly species living on the summit of the Roraima-tepui shifted its diet from soft-bodied invertebrates to a small endemic toad species supposed to be its (potential) predator. And, probably to better ambush its prey, that firefly larva stopped glowing, which seems unique in the firefly family. Firefly larvae are unpalatable and glow to deter potential predators, but what’s the point to deter a predator you want to prey upon? The victim here is a toad named Oreophrynella quelchii, which is only found on the summit of two neighbouring tepuis.

Hostile environment

Tepuis are Precambrian sandstone tabletop mountains reaching up to ca. 3,000 m in elevation and are found in northern South America. Their highest summits are isolated from the surrounding uplands savannah and lush tropical rainforest by sheer cliffs and face particularly hostile, challenging environmental conditions. These isolated tabletop mountains inspired Sir Arthur Conan Doyle for his famous novel The Lost World, populated with dinosaurs and an ancient civilisation.

Philippe Kok is a specialist of the evolution of vertebrates in these remote areas and spent close to 300 days on tepui summits.