American Rhinoceros Beetle

Xyloryctes jamaicensis
Wednesday, July 13, 2011

This large beetle is one of the Dynastinae Subfamily, all called Rhinoceros Beetles. Part of the Scarab family, Rhinoceros Beetles are typically large, robust beetles with rounded dorsal surfaces. Several groups have prominent horns on their heads, which gives this group its name.

Xyloryctes jamaicensis is a showy beetle. Both sexes are large and reddish-brown colored and are typically 25-28 mm long (1-1⅛ in). The mandibles are small, and the sides of the beetle are fringed with reddish-brown hairs. The male X. jamaicensis has a “squared-off” pronotum (the section of the body between the thorax and the head) and a large horn protruding from his head. The females have a small tubercle (round nodule) in place of a horn. This species is distinguished from its close relatives by having just one horn, centered, and striations (grooves) on the elytra (wing covers).

When male and female beetles mate, the females lay their eggs in the soil. The larvae, large grubs, emerge and feed on decaying organic matter or the roots of ash trees. The adults emerge in the summertime, but only live for a few months until early fall. While in the adult form, they consume ash foliage.

This beetle is among the several species of large beetles coveted, kept, and bred by insect collectors. In the wild, however, it occurs commonly over most of the eastern US, from New England south to Florida, and can be found as far west as New Mexico. 

This specimen was discovered by the Beetle Crew crawling in cut grass on the station. The dead specimen is the same species, but was discovered last year. Both specimens are male.

Article by Hazel Galloway