What's That Bug? does not endorse extermination

Rhinoceros Beetle
Fri, Mar 20, 2009 at 9:28 AM
Hello Again!
Found this little guy struggling in a pool, a few months back. I assume he’s some species of Rhinoceros beetle (what else could you call it?). Fairly small – from memory, I’d say just about 1/2″ long, no larger (sorry no size reference in the photo).
Found in Santa Cruz Mountains, Los Gatos CA
Out of curiosity, is there an ideal size photo for submissions? OK if I send you a full-size 8 MB file of some critter in the future?
Santa Cruz Mountains CA

Horned Dung Beetle

Earth Boring Dung Beetle

Dear NewtHunterDave,
We believe this is a Dung Beetle. Dung Beetles and Rhinoceros Beetles are both Scarab Beetles. Males in the genus Phanaeus, known as Rainbow Scarabs, have horns. BugGuide shows a species, Phanaeus amithaon, from Arizona, but we are not convinced this is your species. We also located a BioOne Online Journal posting,
Copyright © 1997 William Ericson ,on a new species from Sonora Mexico, Phanaeus yecoraensis, and the detail photos resemble your specimen as well. The horn on your specimen is quite distinctive. We will seek assistance from Eric Eaton on this identification. Regarding the image size, both the Salamander image and Dung Beetle image you sent that we posted were ideal. Since our site migration last September, our site has the option of clicking on the image to see a larger version. We post no larger than 800 pixels wide by 550 pixels high at 72 dpi, and the program selects the ideal thumbnail to display. We prefer larger images so we can crop and resize to maximize what our site offers.

I’ll include a couple other photos of this guy from different perspectives in case that helps with the ID.
(Although, for my purposes, ‘dung beetle with a horn’ is probably close enough!)
Also, for what it’s worth, he was shiny, but I didn’t notice any sort of iridescent or metallic/rainbow effects on this beetle.  If I had, I would have tried hard to capture that in a pic.

Unknown Dung Beetle with Horn

Earth Boring Dung Beetle

Update: Freom Eric Eaton
Hi, Daniel:
Sun, 22 Mar 2009
One I actually recognize! LOL! It is one of the “earth-boring scarabs” in the family Geotrupidae. The species is Odonteus obesus. The specimen is a male. There are some nice images on Bugguide, but we could use a few more if the submitter wants to post there. Thanks.

Thanks Eric,
Since all the specimens on BugGuide are mounted, we will ask NewtHunterDave to post his beautiful live images.

What's That Bug? does not endorse extermination

3 Responses to Earth Boring Dung Beetle

  1. Chris says:

    Are these dung beetles rare? I found one — looks exactly the same — in the Los Gatos Mnts. Have good picture if interested.

    • bugman says:

      You may submit your image using the Ask What’s That Bug? link on our site. Please use Dung Beetle in the subject line.

    • NewtHunterDave says:

      Chris, the specimen pictured is also from Los Gatos Mountains. I seem to find exactly one male in the pool, every year, at the same time each year (within a couple of days). Probably not terribly rare, just rarely seen.

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