Caterpillar Hunter

Subject: Unknown Insect Larva
Location: Denver, Colorado
May 28, 2016 5:08 pm
Dear WTB,
While on a walk through my neighborhood in Denver, I found this black insect larva crawling around the sidewalk.
It was fairly large, I’m guessing around 1-1/2″ long, and moved at several inches per second, making taking a good photo a little tricky. This happened today, May 28th. The area is a low-density urban neighborhood with lots of yards, lawns, gardens, and trees. There are water sources in the general area, but not near where the insect was found.
I’m guessing this is some type of beetle larva, but I’ve definitely never seen this species, or one that come close to this size, before.
Signature: Duncan

Caterpillar Hunter
Caterpillar Hunter

Dear Duncan,
This is the larva of a Caterpillar Hunter, a Ground Beetle in the genus
Calosoma.  Both larvae and adults from this genus consume large numbers of caterpillars.  See this BugGuide image for comparison.  We are postdating your submission to go live to our site during our absence from the office in mid-June.

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