BEETLES OF EASTERN NORTH AMERICA: EASTERN HERCULES BEETLE
By Arthur V. Evans
The eastern Hercules beetle, Dynastes tityus (Linnaeus) (40.0 to 60.0 mm) is a large, spectacular olive-green animal mottled with irregular black spots. Well-hydrated individuals, especially those feeding or have just fed, are sometimes almost completely dark.
Males have a single horn on the head that is held in apposition to the largest of three on the pronotum. Together, these horns are used like forceps to dislodge rival males from sapping spots on the branches of ash trees. These sapping spots provide food for both sexes and are created by males specifically to attract hornless females.
Eastern Hercules beetles are found throughout much of eastern United States, from New York south to Florida, west to southern Illinois, western Arkansas, and eastern Texas. Both sexes are often encountered at lights, but seldom in numbers. However, large numbers of individuals are reported aggregating on ash (Fraxinus) or in tree holes used as breeding sites.
The larvae develop and feed on rotting wood of various hardwoods, especially oaks, and occasionally pine. Large tree holes are sometimes used continuously as breeding sites year after year where the larvae feed on damaged rotten and crumbling heartwood; no harm is done to living trees. Their dark, rectangular fecal pellets are quite distinctive.
The entire life cycle of eastern Hercules beetles may take two or three years, depending on conditions. Adults live several months in captivity on a diet of soft fruits cotton balls saturated with a 1:1 solution of water and maple syrup.
© 2010, A.V. Evans