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Snail-Eating Beetle - Scaphinotus ridingsii

Snail-Eating Beetle - Scaphinotus ridingsii
Holly River State Park, Webster County, West Virginia, USA
October 8, 2005
The other photo allowed a closer look at various structures of the beetle, but this one includes all legs and antennae and more of the millipede.

Using Dillon & Dillon, and judging primarily by the shape of the pronotum, I believe this is Sphaeroderus lecontei.

Images of this individual: tag all
Snail-Eating Beetle - Scaphinotus ridingsii Snail-Eating Beetle - Scaphinotus ridingsii Snail-Eating Beetle - Scaphinotus ridingsii


Moved from Scaphinotus.

I have an old copy of Dillon and Dillon with me so I can see what you were thinking. But look how narrow the pronotum is on your beetle. Also the head, mandibles, legs, and antennae are just too long for Spaeroderus. It's funny that I just sent you an email about how hard these are to find in the northeast but this is the real deal! You have some species your way that I'm not overly familiar with but I think this is Scaphinotus andrewsii which is one of the small/medium sized scaphinotus beetles. And no they don't just eat snails. Awesome find and great photo!

Wow, Scaphinotus!
Thanks, for the ID, Frank! I had thought in passing that the beetle looked similar to your Scaphinotus photo. I see now that the mouthparts in my photo are much longer than in Sphaeroderus.

Google image search revealed no images on the web of Scaphinotus andrewsii, though I did find a drawing in How to Know the Beetles. I wonder if in my photo the pronotum isn't too wide and "heart-shaped" compared with the S. andrewsii drawing? I've just posted another photo that shows the pronotum better and how much it tapers toward the rear.

I'll move this to the Guide Page for genus Scaphinotus for now, the first eastern record for the genus to go onto the BugGuide range map. Cool!

Thanks again for your help. Now I'll have to dig out the photos of the other two ground beetles I photographed in that park that day!


Stephen Cresswell
Buckhannon, WV

How big?
You are right that the pronotum in that picture doesn't look quite right for andrewsii. (believe it or not there is a photo of that species in Yanega's longhorn book in the "not a longhorn section" - scaphinotus beetles do tend to have very long thin antennae). The pronotum sort of looks like S. viduus but really there are quite a few species that it could be. How big was it? Unfortunately I don't think I have much more to add. We need a Scaphinotus expert here.

Frank, would you agree this resembles ridingsii rather than andrewsii? I've been trying to better understand the Steniridia species lately, and this photo has been messing with me.
That smooth, cordate pronotum, the regularity of the elytral intervals, plus that millipede for scale (suggesting this is a pretty small scaph) make me think it's ridingsii.

It'd be kind of a shame if I was right, since this picture was published in "Beetles of Eastern N. America" as 'S. andrews*ii'.

i agree this is S.ridingsii
Yes, the overall shape and smaller size (relative to that species of millipede) definitely point to S.ridingsii. I sort of forgot about this bug, but over the last few years have read Valentine's paper and visited the huge Steniridia collection at the Carnegie. Also, I collected both species for the first time this summer near Hillsboro,WV. The pronotum of S.andrewsii is quite variable throughout its range but I think the suspecies in that part of WV (either mutabilis or germari) doesn't have such a heart-shaped pronotum like S.r.monongahelae does.