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Snail-killer Carabid - Scaphinotus angusticollis

Snail-killer Carabid - Scaphinotus angusticollis
Victoria, (Mount Douglas Park), British Columbia, Canada
September 9, 2005
This ground beetle is very common throughout Vancouver Island and although it generally hides under forest litter and decomposing logs during the day, it is at times quite active in broad daylight. Its head is adapted to get to those hard to reach places inside a snail's shell. In the coastal forest of an urban park (such as Mount Douglas Park), it probably makes a good living on a variety of non-native slugs introduced from surrounding gardens.

Images of this individual: tag all
Snail-killer Carabid - Scaphinotus angusticollis Snail-killer Carabid - Scaphinotus angusticollis

As a note
As a note, that is angusticollis. Very, very common in Washington State. There is a state park called Rockport with old growth forest still intact, the bug is so common it might as well hop into your collecting jar.

It can be IDed from the other members of the genus in the area by the fine lines on the elytra, and the velvety wine color. All other Scaphs in Washington have a more shiny mettalic color, or are a differnent size.

Moved to species guide, Scaphinotus angusticollis
I moved this to a guide page for the species Scaphinotus angusticollis. Browing the web, I seems that this is a very common species in the Pacific Northwest. However I cannot find any images confidently identified as this species, nor other identification keys. I did find a photograph and an illustration in print sources, but again, no keying inforamtion. (See guide page.) Here are two references:

North Cascades National Park: Terrestrial Riparian Arthropods--apparently most commonly taken member of genus in that survey
Ground Beetles of Canada--on checklist for British Columbia, along with a couple of other members of this genus, but no linked image

Do you have any more information on how this identification was made?

Patrick Coin
Durham, North Carolina

Specific name in doubt.
The generic name for this ground beetle is indisputable. I must admit, however, that the specific name for this specimen was decided not upon the strictest of scientific grounds. The insect is pictured (with an illustration) bearing the name "angusticollis" in Bugs of British Columbia by John Acorn and Ian Sheldon, Lone Pine Publishing 2001.

A good Internet source is:

I have seen this insect in Vancouver Island forests for the last 15 years and I have never suspected that there may be more than one similar-looking species (on account of pronotum width or any other such notion). I will dig a little further and see if there is greater complexity here than meets the eye. Thank you for keeping me on my toes -- I may have been a bit too casual with this identification.

Thanks for clarification, "Bug of the Month" convincing
No disrespect of your identification skills was intended. The sources I found certainly indicated S. angusticollis is the commonly encountered species in your area. Carabids (and many other groups) are very difficult. Without extensive keying, it's often hard to decide whether to leave photos at the genus level, or put under a species where one is 90-plus-percent sure of it, based on collection frequency, matching appearance in popular guides, etc. Purists will say always to leave at genus level absent a formal key, but I can't agree with that--one may lose interesting information about species distribution and ecology by not making some plausible identifications. We've never reached complete agreement on this site about such issues. The great thing about it is that errors can be corrected at a later date, and new knowledge about field identification can be gained by looking at lots of photos from many parts of North America.

Oh, also, I see that "Bug of the Month" article is pretty detailed on features of several different Pacific Northwest species. That's convicning enough for me, in any case.

I look forward to seeing more insects from British Columbia. I've visited there just once, and would love to go back.

Patrick Coin
Durham, North Carolina