A rare species of clearwing moth, that appears to mimic a bee, has been rediscovered in the rainforests of Malaysia after being ‘lost’ for 130 years. Scientists have recorded footage of the metallic blue moths (Heterosphecia tawonoides) flying around the banks of rocky streams as described in an article published in Tropical Conservation Science. ‘When I first saw the clearwing in the Malaysian rainforest, I was absolutely amazed. It was beautifully coloured: shiny blue in sunlight… I couldn’t think of any specimen from literature or museums which had that kind of colouration,’ said the lead scientist Marta Skowron Volponi.
The clearwing moth Heterosphecia tawonoides hasn’t been seen alive since 1887 – Footage by Marta Skowron Volponi and Paolo Volponi
Heterosphecia tawonoides was originally discovered in Indonesia in 1887. The specimen was deposited in the Natural History Museum in Vienna and, as far as we know, it hasn’t been seen alive since. After finding unique iridescent blue moths in the Malaysian rainforest, scientists compared them to museum specimens and discovered that they had rediscovered the elusive Heterosphecia tawonoides. ‘In total, during several years of studies, we only observed 12 individuals of this species,’ says Skowron Volponi.
Filming these clearwing moths for the first time has revealed some remarkable aspects of their biology that were previously unknown. Their narrow transparent wings, combined with tufts of white hair-like scales and blue iridescent scales across their body, means that at close glance they look more like a bee than a moth. The dull buzzing sound of their wing beats only adds to the illusion. ‘I usually also have to wait until the clearwing moth lands to be sure it’s not a bee! In flight, they are perfect mimics,’ says Skowron Volponi.
The clearwing moths of the family Sesiidae, to which Heterosphecia tawonoides belongs, are famous for their deceptive appearances. Another newly described clearwing moth Pyrophleps ellawi, also from Malaysia, looks remarkably like a wasp. Having thin wings, long slender bodies and black and orange colouration, it would likely take a skilled entomologist to correctly identify these insects as actually being moths.
Resembling bees and wasps is a common strategy for protection. Many insects, including flies, beetles and moths, are known to sport bright yellow bands and make buzzing sounds as they fly. Despite being harmless insects predators often cautiously avoid these tricksters on the chance that they are packing a dangerous sting.
The scientists also observed a curious behaviour called ‘mud-puddling’ where the moths would land near moist patches of ground near the edge of streams and use their long mouthparts to ’lick’ water from the surface of rocks and soil. In other moth species their long mouthparts, or proboscises, are used to drink fluids such as nectar. However in many species of tropical butterflies and moths the proboscis is used in ‘mud-puddling’ to ingest important minerals and nutrients dissolved in groundwater.
The native habitat of Heterosphecia tawnoides is deep in the rainforest, very little is known about the animals and plants that live there. ‘I reached the area… by boat and on foot, carrying all our camping and filming equipment… everything we needed to survive in the jungle on our backs,’ says Skowron Volponi. These early observations open up new possibilities for research that will uncover more about the behaviour and ecology of this resurrected species.
Whilst encountering a species presumed to be extinct is an exciting discovery, it highlights the vulnerability of these rare animals to extinction. Scientists believe that clearwing moths may be especially vulnerable to climate change and deforestation. This is especially worrying given that Malaysia has some of the highest deforestation rates in the world.
‘The rediscovered species is just an example of an animal associated with unique habitats within primeval rainforests. Most probably, it won’t be able to survive in human-modified habitats and will vanish along with many other species if the jungle disappears,’ says Skowron Volponi. With ongoing destruction of South East Asian rainforests it appears we may be losing species faster than scientists are able to discover them.
Article by James O’Hanlon
James is a research scientist and science communicator currently based at the University of New England, Armidale. He hosts the In Situ Science podcast and is sick of hearing people say bad things about spiders.