An Illuminated Hunt
In the vast grasslands of Emas National Park, a UNESCO World Heritage site, millions of earthen towers dot the area. These are the nests of the termite Cornitermes cumulans, which can reach over two meters in height. For a few weeks each year, typically at the start of the rainy season in September and October, these mounds transform into a rare spectacle. After sunset, they begin to glow with thousands of eerie green lights, resembling a bright city.
The light is not from the termites. It is produced by the larvae of a click beetle, Pyrearinus termitilluminans. Adult beetles lay their eggs in the sides of the termite mounds. When the larvae hatch, they burrow into the mound's hard outer shell, creating a network of tunnels. Each larva then emits a steady green glow from its prothorax, the segment just behind its head. The number of glowing larvae can be substantial; after the first rains, a single mound may host nearly 180 individual points of light. This phenomenon is a carefully timed predatory strategy, synchronized with the annual mating flights of the termites and other insects.