The western Hercules beetle (''Dynastes grantii'', often misspelled as "''granti''") is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

rhinoceros beetle Dynastinae or rhinoceros beetles are a subfamily of the scarab beetle family (Scarabaeidae). Other common names – some for particular groups of rhinoceros beetles – include Hercules beetles, unicorn beetles or horn beetles. Over 1 ...

that lives in

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ker ...

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...

and parts of northern

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

. This species is known for its grayish-white

elytra An elytron (; ; , ) is a modified, hardened forewing of beetles (Coleoptera), though a few of the true bugs (Hemiptera) such as the family Schizopteridae are extremely similar; in true bugs, the forewings are called hemelytra (sometimes alterna ...

, large size, and characteristic horn of the adult males.

Description

Adult body sizes of both sexes vary from 35 to 60mm (apex of elytra to apex of thoracic horn), with captive-reared individuals reaching up to 80mm. Coloration of the

varies from white to grayish-white, often with irregular black spots of various size and number. At high humidity levels, the elytra may appear black. ''Dynastes grantii'' is

sexually dimorphic Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

, with the females lacking the characteristic horns of the male.

Life Cycle

Like other

Hercules beetle The Hercules beetle (''Dynastes hercules'') is a species of rhinoceros beetle native to the rainforests of Central America, South America, and the Lesser Antilles. It is the longest extant species of beetle in the world, and is also one of the ...

species, ''Dynastes grantii'' undergoes a six-stage life cycle from egg to adult, with three larval instars and a single pupal stage. The time from egg to pupal eclosion is estimated to take approximately two years. The pupal stage lasts about 30 days. Adults emerge from the pupal chamber between the months of August through October and typically live between two and four months in the wild. In captivity, the adults may live up to nine months. After mating the female oviposits over 100 eggs.

Distribution and habitat

Populations of ''Dynastes grantii'' may be found in southern

, western

of the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

, and parts of Northern

. This species typically inhabits highland forest habitats, at or above 1600m ASL.

Feeding Habits

Adults have been documented feeding on the

cambium A cambium (plural cambia or cambiums), in plants, is a tissue layer that provides partially undifferentiated cells for plant growth. It is found in the area between xylem and phloem. A cambium can also be defined as a cellular plant tissue from w ...

ash trees ''Fraxinus'' (), commonly called ash, is a genus of flowering plants in the olive and lilac family, Oleaceae. It contains 45–65 species of usually medium to large trees, mostly deciduous, though a number of subtropical species are evergr ...

. The beetles strip the bark from small branches and feed on the sap produced by the exposed cambium.

Similar species

''Dynastes grantii'' belongs to the White Hercules beetle linage which includes five allopatrically distributed

North American North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Ca ...

and

Central American Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. Ce ...

taxa, including ''

Dynastes hyllus ''Dynastes hyllus'' is a large scarab beetle species that ranges from Mexico to Guatemala. Its larvae have been found to associate with the logs of ''Persea americana''. Taxonomy There were two subspecies recognized, ''D. hyllus hyllus'' and '' ...

'', ''Dynastes maya,

Dynastes moroni ''Dynastes moroni'' is a large scarab beetle endemic to the Sierra de los Tuxtlas region in Mexico.Ratcliffe, B. C., R. D. Cave, and E. Cano. 2013. The dynastine scarab beetles of Mexico, Guatemala, and Belize (Coleoptera: Scarabaeidae). Bulleti ...

,'' and ''

Dynastes tityus ''Dynastes tityus'', the eastern Hercules beetle, is a species of rhinoceros beetle native to the Eastern United States. The adult's elytra are green, gray or tan, with black markings, and the whole animal, including the male's horns, may reach ...

''. Despite differences in geographic origin and morphology, namely horn length and coloration of the elytra, ''Dynastes tityus'' and ''Dynastes grantii'' are very similar and it is possible for the two species to produce hybrids. Some scientists believe that the two beetles are actually subspecies given the similarities of the male genitalia. ''Dynastes grantii'' is very similar morphologically to ''

'', with differentiation between species often only possible through examination of geographic origin.

Distinction from ''D. hyllus''

The body coloration of ''

'' is typically yelloiwsh to brownish where it is white to grayish-white in ''Dynastes grantii.'' The significant protrusion forward of the bottom tooth at the base of the thoracic horn in males of ''

'' is also a distinguishing factor between the two species. While ''

'' can be distinguished morphologically from ''Dynastes grantii,'' geographic origin is generally the strongest factor in correct identification. Dynastes_granti_m2

A comparison between a male ''Dynastes grantii'' (left) and a male ''

'' (right)

Additional images

File:Dynastes granti, Pine AZ.jpg, Adult male File:Insect Safari - beetle 43.jpg, Adult female File:Dynastes granti m.jpg, Adult male File:Dynastes granti f.jpg, Adult female

References

External links

* * Dynastinae Beetles of North America Beetles described in 1870 {{Dynastinae-stub