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Western Hercules Beetle (Dynastes grantii)

The western Hercules beetle of the scarab beetle family is a rhinoceros beetle species, easily identifiable by its big size, and characteristic horns of the males. It is one of the five White Hercules beetles found in the Americas, alongside Dynastes hyllus, Dynastes maya, Dynastes moroni, and Dynastes tityus.

Western Hercules Beetle

Scientific Classification

  • Family: Scarabaeidae
  • Genus: Dynastes
  • Scientific name: Dynastes grantii

Physical Description and Identification

Adult

Size: 35 to 60mm

Color: Their elytra range from white to grayish-white, marked irregularly with black spots, varying size as well as number. However, in times of intensely humid conditions, the elytra might appear black.

Other Characteristic Features: The females lack the horns, seen in males.

Dynastes grantii

Larva

They take almost two years to emerge from their eggs and then go through three instars to become fully mature. The grubs appear white and C-shaped, with a red head.

Western Hercules Beetle Larvae

Pupa

After maturing, the larvae begin to pupate, staying in this stage for 30 days. The adults mostly emerge between August and October.

Egg

Females lay over 100 eggs after the mating season.

Western Hercules Beetle Eggs

Quick Facts

Lifespan2-4 months
DistributionArizona, western New Mexico, and southern Utah in the United States; parts of northern Mexico
HabitatHighland forests
Seasons activeAugust – October
Host plantsSycamore trees
Diet of adultsThe sap of plants like ash trees
Western Hercules Beetle Image

Identifying the Damage Caused by Them

The adults feed on the sap of trees, while the larvae thrive on decayed wood. Thus, they cause no significant damage to the trees.

Did You Know

  • The Western Hercules has a striking similarity with the Hyllus beetle, another rhinoceros beetle species, differing mostly by color. The latter is yellowish or brownish, while the former appears whitish or grayish.
Western Hercules Beetle Picture

Image Source: bugguide.net, uky.edu, th-thumbnailer.cdn-si-edu.com

The western Hercules beetle of the scarab beetle family is a rhinoceros beetle species, easily identifiable by its big size, and characteristic horns of the males. It is one of the five White Hercules beetles found in the Americas, alongside Dynastes hyllus, Dynastes maya, Dynastes moroni, and Dynastes tityus.

Western Hercules Beetle

Physical Description and Identification

Adult

Size: 35 to 60mm

Color: Their elytra range from white to grayish-white, marked irregularly with black spots, varying size as well as number. However, in times of intensely humid conditions, the elytra might appear black.

Other Characteristic Features: The females lack the horns, seen in males.

Dynastes grantii

Larva

They take almost two years to emerge from their eggs and then go through three instars to become fully mature. The grubs appear white and C-shaped, with a red head.

Western Hercules Beetle Larvae

Pupa

After maturing, the larvae begin to pupate, staying in this stage for 30 days. The adults mostly emerge between August and October.

Egg

Females lay over 100 eggs after the mating season.

Western Hercules Beetle Eggs

Quick Facts

Lifespan2-4 months
DistributionArizona, western New Mexico, and southern Utah in the United States; parts of northern Mexico
HabitatHighland forests
Seasons activeAugust – October
Host plantsSycamore trees
Diet of adultsThe sap of plants like ash trees
Western Hercules Beetle Image

Identifying the Damage Caused by Them

The adults feed on the sap of trees, while the larvae thrive on decayed wood. Thus, they cause no significant damage to the trees.

Did You Know

  • The Western Hercules has a striking similarity with the Hyllus beetle, another rhinoceros beetle species, differing mostly by color. The latter is yellowish or brownish, while the former appears whitish or grayish.
Western Hercules Beetle Picture

Image Source: bugguide.net, uky.edu, th-thumbnailer.cdn-si-edu.com

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