Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
Photo#43891
Scaphinotus viduus mandibles detail - Scaphinotus viduus - female

Scaphinotus viduus mandibles detail - Scaphinotus viduus - Female
7 km East of Paw Paw, Morgan County, West Virginia, USA
August 26, 2000
Size: 30 mm
Detailed view of highly intricate mandibles. Note the four setae at the base of the clypeal cleft. Most keys list that character to separate Scaphinotus from Sphaeroderus that have two such setae.

Images of this individual: tag all
Scaphinotus viduus - female Scaphinotus viduus mandibles detail - Scaphinotus viduus - female Scaphinotus viduus - female

Great image Frank!
Great image, Frank! Six or seven paired body parts all lined up. This would be a great illustration to go with an introduction to beetle anatomy.

--Stephen

Stephen Cresswell
Buckhannon, WV
www.stephencresswell.com

snail eater?
Of course the conventional wisdom is that the highly intricate mandibles are supposed to allow the beetle to eat snails hiding in their shells although I have never seen this behavior myself. This beetle was found while eating a hairy caterpillar. Stephen Cresswell has a nice image on Bugguide of a Scaphinotus beetle attacking a millipede. Over the summer of 2005 I found another Scaphinotus viduus in my back yard in Monkton, Maryland. In captivity, it refused to touch snails, slugs, earthworms, millipedes, mealworms, and several species of caterpillars. However it seemed quite fond of watermellon! There is at least one Bugguide image of a Carabid beetle eating a snail (also by Stephen Cresswell) but that beetle is probably Carabus serratus which does not have particularly elaborate or specialized mandibles so this adaption is apparently not absolutely required for snail eating. I am very interested in Scaphinotus beetles and would love to hear about observations in this regard from anyone else out there.