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Dynastes hercules
Range:  Central America, northern South America and nearby islands
Size:  50 - 170 mm

Of all the world's rhinoceros beetles, Dynastes hercules is probably the most famous.  Scientific records of this insect from several hundred years ago exist, and to this day it remains a favorite among beetle enthusiasts.  An inhabitant of the rain forests of Central and South America, it is a real giant having a body length of up to 170 mm (6.75 in.).  Perhaps the most distinctive features of this species are the thoracic and cephalic horns of the male, which often reach lengths even longer than the insect's body itself.  The underside of the thoracic horn is lined with a thick band of fine brown hairs.  The upward curving horn on the head (the "cephalic" horn) can be moved upward against the longer, downward curving one (the "thoracic" horn) which projects from the beetle's pronotum (the dorsal shield of the thorax).  This beetle has evolved the insect equivalent of a large, slender, grasping claw rather similar to that of a fiddler crab, but rather than it being an appendage located on an arm, it has been developed as extensions of the head and thorax.  As is the case with other members of the scarab subfamily dynastinae, the horns are used as pry bars during disputes with other males over mates.  There are a number of subspecies distributed across Central America and northern South America which can be distinguished primarily by the particular shape of their horns.  There are six species in the genus Dynastes, and two of them, D. granti and D. tityus, occur within the United States.

You can read an excellent article by beetle hobbyist Yasuhiko Kasahara about the captive breeding of Dynastes hercules here.

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An excellent photograph of a male D. hercules.  This particular individual does not bear the many small black spots on the elytra which are typical of most examples of the species.

Image courtesy of Guy Bruyea.

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Dynastes hercules (male) - Image © Guy Bruyea

 
Dynastes hercules (male)
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From the photo at left of a male D. hercules sitting on a person's arm, you can get a good impression of the incredible size of this spectacular insect.  Although giant beetles such as this may appear fearsome or even dangerous, they are actually quite harmless to humans.  It is very important that this insect's natural habitat be protected from destruction, otherwise amazing species such as D. hercules will have no place to live.  To survive, they require old growth rain forests containing large decaying logs.
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An example of a male with very exceptional horn development.  Not all males exhibit such large horns as this.  There is much variation in body size, which affects the extent to which the horns are developed.  This is related to the amount and nutritional quality of the food which the beetle consumed as a larva.

Image courtesy of NAOKAWA.

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Dynastes hercules hercules - Image © NAOKAWA

 
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