The adult's elytra are green, gray or tan, with black markings, and the whole animal, including the male's horns, may reach 60 mm (2.4 in) in length.

[4] Beetles that are found in the soil or in rotten wood often appear very dark, with the spots on the elytra obscured.

This results from moisture which the shell has absorbed; when the elytra dry out, they return to their paler color.

[1] Dynastes tityus was featured on a stamp issued by the United States Postal Service in October 1999.

[1] The external humidity level leads to the elytra color change for the eastern Hercules beetle.

When the environment is dry, the space between the multilayers is filled up with air and the refractive index has a low value of 1.

[8] They fuse with each other and build an ordered structure which can store energy to protect the wing and body.

When the elytra appears deep brown under the high humidity environment, it can better defend the beetle from attacks and accidents.

The North American lineage appeared after the closure of the Panama Isthmus 3.5 million years ago.

[9] This lineage has been further dispersed by the Transverse Volcanic Belt and the Sierra Madre del Sur into eastern and western species in North America.

[10] D. tityus lives in the eastern and southeastern United States, from New York state, Illinois and Indiana in the north to Florida and the Gulf of Mexico in the south, with eastern Texas and western Arkansas marking the western limit of its range.

[13] The larvae are large C-shaped grubs with white bodies and chewing mouthparts,[5] which feed on decaying wood and litter within rotten trees and produce distinctive rectangular fecal pellets about 10 mm (0.39 in) long.

Females may share the same site to lay the eggs if there are enough accumulations of woody debris as food resources.

Eggs have an incubation period of about one month, followed by three larval instars, which refer to molting stages of the larvae.

The larvae are large C-shaped grubs with white bodies and chewing mouthparts,[5] which feed on decaying wood and litter within rotten trees and produce distinctive rectangular fecal pellets about 10 mm (0.39 in) long,[13] which functions has a house for them to develop during both larvae and pupae stages.

Individuals and mating pairs are commonly found to stay on the ash trees and scrape off the bark and feed on sap.

[14] The larvae are saproxylophagous, meaning they feed on dead wood, such as rotten logs and decaying tree trunks.

[10] While D. tityus inhabits the eastern United States, Dynastes grantii (the western Hercules beetle) live at higher elevations in Arizona, New Mexico and Utah.