Zylorictes thestalus

   These scarabs swarm on certain nights of the year, and can blacken the ground if you find them on just the perfect night.  Little is known about their habits, but they apparently burrow into the ground during the day.  Males have an emphasized horn on the tops of their heads, although they don't seem to use it for fighting.  Females lack the horn, and are able to burrow just as quickly as the males.