At night, if you shine a black light into some Vietnamese forests, you might see vivid green LEDs glowing in the trees.
Researchers describe in the August Journal of the Royal Society Interface that the spooky lanterns are the nests of many species of Asian paper wasps, and the gleam derives from silk threads in the nests that fluoresce when struck by UV light.
Molecular Electrochemistry Lab at the University of Paris and CNRS chemist Bernd Schöllhorn adds, "When you see it, it's absolutely wonderful."
The nests were discovered by Schöllhorn and colleagues while looking for fluorescent insects in Vietnam forests using powerful UV lamps.
“It appeared like someone in the forest turned on a flashlight, but nobody was there,” he claims.
Fluorescence can be seen in all kinds of animals.
Platypuses, scorpions, and polka dot tree frogs, for example, all glow in the presence of ultraviolet light (SN: 11/6/20; SN: 4/3/17).
The researchers discovered that silk threads in the nests of some Asian paper wasps (Polistes spp.) shine more brilliantly than other recorded fluorescent biomaterials after studying the fluorescence of the nests in the lab. One wasp species, P. brunetus, emitted around one-third as much light as it absorbed in its nest.
The nests could be seen by the naked eye from up to 20 meters distant in some situations.
“We haven't seen anything like it before,” Schöllhorn says.
The wasps must profit from the fluorescence in some way.