...When fed a steady stream of ultraviolet rays, all of the nests glowed, each with a bit of regional flair: The four from Vietnam all pulsed in green, while the other two, from Europe and South America, were a more muted teal-ish blue. ... ...The wasps themselves didn’t light up; neither did the topmost parts of the nests, constructed out of chewed-up wood (hence the “paper” moniker). The glow, the researchers found, came from....