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Photo#33577
What type of Beetles? - Sandalus niger - male - female

What type of Beetles? - Sandalus niger - Male Female
Poseyville, Posey County, Indiana, USA
October 1, 2005
Size: 1/2" - 1.5"
I'm hoping someone can identify these beetles I found on a silver maple tree in my yard. Close to these two mating was what appeared to be a family of them - with the larger (female - thanks!) beetle carrying three others on its back! Very intriguing.

There are also a few other smaller brown ones (male) swarming around the tree. Later I saw the larger black beetle alone, and it seemed to be depositing something under the bark of the tree (eggs?). Never saw them before today. Anyone have a clue as to what these critters are?

Images of this individual: tag all
What type of Beetles? - Sandalus niger - male - female What type of Beetles? - Sandalus niger - male - female What type of Beetles? - Sandalus niger - female

Moved
Moved from Sandalus.

Very interesting!
Thanks for everyone's help! I've added a couple more photos.

Sex differences
The one with the fancy antennae is the male. The female is bigger than the male; this is quite common among insects. So, you probably saw a female ovipositing, laying eggs. Also, the larger one with three on its back was probably a female with three males competing for a chance to mate.
Very interesting observations. Do you have more pictures?

fantastic!
Moved to correct family, see Eric's comments under other photo in guide.

 
Photos match Sandalus niger
Sandalus niger is described as 21-25 mm, with females black, about 1/3 larger than males, which are reddish or black. Several references on this--see guide page for Sandalus, i.e.,

White, p. 154, fig. 60--Sandalus niger (1)
Arnett et al. pp. 186-187, fig. 453--Sandalus niger (2)
Brimley, p. 164, lists S. niger for North Carolina, describes females as black, males as red or black. (3)
Salsbury, p. 188, photo of male Sandalus niger (4)

White also lists S. niger as the most widespread eastern species.

Patrick Coin
Durham, North Carolina

 
Sandalus?
Is Sandalus the only North American genus? What on-line references I can find seem to imply that. I wrote a quick guide, if that is the case.

Excellent photo.

Patrick Coin
Durham, North Carolina

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