A creature inhabits northern Arizona that has every appearance of a diminutive rhinoceros.
If you see a large grey-bodied beetle dotted with irregular black spots — and sporting two prominent horns if it’s male — it’s likely a Western Hercules Beetle.
For the first two years of life these beetles are hidden from view, developing as larvae in decomposing logs and old tree stumps, where they feed on rotting wood. Then in mid-summer, inside a hardened case made from their own poop, they transform into pupae, then adults, over a period of thirty days.
On humid late summer nights the fully formed adults hatch. They’re one of the largest flying insects in North America at two to three inches in length. They gravitate to stands of ash trees especially in riparian areas, from Flagstaff, Prescott, to Payson and along the Verde Valley, where they’re active from late July to October.
To spot them, find an ash tree and look up. Adult beetles often hang out on thin ash branches six feet or more off the ground.
As breeding gets underway, male beetles display so-called ‘lekking’ behavior. Males scrape bark from the base of an ash tree, creating a sap-oozing wound which attracts females. If another male comes along, the two will lock horns and fight for mating rights.
Males die after mating, while the females live another two-to-four months, laying their eggs in rotting wood, where the cycle begins again.
This Earth Note was written by Diane Hope and produced by KNAU and the Sustainable Communities Program at Northern Arizona University.
