Friday Beetle Blogging: Dynastes granti, the Western Hercules Beetle

A male western hercules beetle, Arizona.

Meet Dynastes granti. This behemouth of an insect is North America’s heaviest scarab beetle, found in the mountains of the American southwest where adults feed on the sap of ash trees. I photographed these spectacular insects a few years ago while living in Tucson.

The impressive pronotal horn on the beetle pictured above indicates a male; females are considerably more modest in their armaments:

Male and female hercules beetles

As is so often the case in animals, males use their horns to fight each other for access to females, attempting to pry their opponents off the branches.  Size is important, and it varies notably among individuals depending on how well they fed as developing larvae:

Size variation among male hercules beetles. My money is on the guy on the right.

The three beetles pictured here lived in our house for a while as pets; they were good-natured insects and would sit happily on our fingers eating maple syrup.

Photo details: Canon 100mm f2.8 macro lens on a Canon EOS 20D.
ISO 400, f3.0-f5.0, 1/50-1/125 sec, ambient light at dusk

13 thoughts on “Friday Beetle Blogging: Dynastes granti, the Western Hercules Beetle”

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  2. Great photos as usual. Every time I see one of these guys I think about the youtube clip you posted a few weeks back, of one cracking open a coke!

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  4. I found one of these boring a hole in the bark of an oak tree in our city park yesterday (6/10/10). I put it in a jar, and overnight it lost all its colorations and markings and turned a dark brownish black. Are these beetles harmful to trees, or what? I went back to the park this morning, and the tree it was boring into was leaking sap from the hole it had bored. just curious if you could give me more info. I have never seen one of these in person before, just seen pictures in entomology books back in school. Thanks in advance for the information.

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  6. HOLY CRAP! Those are the creapiest, coolest, things I have ever seen. The statement of “…lived in our house for a while as pets; they were good-natured insects and would sit happily on our fingers eating maple syrup…” must be the most humanizing description of a huge, scary looking bug I have ever heard!

  7. I photographed a beetle that looked similar to this while in Cambodia his year. The one I saw was more dark brown in color, and about the same size as the one you picture here. Do you know what these beetles are called in Southeast Asia?

  8. I just discovered a Dynastes granitii in my yard — In BETHESDA, MARYLAND! Apparently there has not before been a report of one in the Mid Atlantic area. So what are the implications?

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