Strange wasp nests glow neon green under UV light

[Still Waters]

While trekking through the tropical forests of northern Vietnam, scientists unexpectedly discovered wasp nests that glow fluorescent green under ultraviolet light.

The nests, which look like a cluster of hexagonal cells, were built by several species of paper wasp, all belonging to the genus Polistes. The wasps seal off the underside of the hexagonal cells with so-called cocoon caps made of silken fibers, which protect the growing larvae within the nest. And for reasons yet unknown, these cocoon caps emit a strong greenish-yellow glow when exposed to UV light between 360 and 400 nanometers in wavelength. 

https://www.livescience.com/glowing-wasp-nests.html

https://royalsocietypublishing.org/rsif/doi/