Slightly iridescent ground beetle

2011 June 25

We found this in the yard almost exactly a year ago, on June 21, 2010. It was 13 mm long, a pretty fast runner, and has a lean, predatory sort of look.

The body shape, head shape, and slight iridescence lead me to it being one of the Carabids. This is a very large family of mostly carnivorous beetles, that tend to be active hunters of things like caterpillars, snails, worms, and other insects.

This particular one was identified by v. belov on BugGuide as probably Poecilus lucublandus, which is one of the Woodland Ground Beetles.

There are a lot of black beetles about this size, but it looks like that iridescent sheen in particular is pretty characteristic of the carabids (although, there are about 30,000 species of carabids worldwide, so I shouldn’t overgeneralize). But, that at least distinguishes them from the other big family of medium-sized black beetles, the Darkling Beetles.

They are reasonably attractive as beetles go, but other than being noted as carnivorous, there doesn’t seem to be much information about this specific genus. They sure are common, though. It seems like we see some every spring. The combination of blackness (low contrast) and reflectivity (specular highlights) does make it difficult to take pictures that do them justice.

3 Responses
  1. July 1, 2011

    If there’s not much known about them, doesn’t that open up lots of opportunities for you to add to our knowledge of these beasties? Life cycle, preferred diet, etc. Could be way cool. You might even get a subspecies named after you!

  2. July 2, 2011

    Yep. Only problem right now is that our younger daughter is way too fond of admiring the bugs I catch, tending to open up the jars they are in to play with them. This makes long-term detailed studies somewhat difficult. Maybe when she’s older, she’ll actually help out in doing this sort of study.

  3. July 2, 2011

    I think it would be great. Poecilus lucublandus eisele has a nice ring to it, don’t you think?

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