Round Worm and Slug Hunter Beetle

2019 May 26
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While I was pushing my bike up the hill on May 13, 2019, I almost stepped on this good sized black beetle. So I popped him in a plastic box and brought him home for pictures.

C.vinctus.dorsal

He was kind of a handsome beetle, black with brassy iridescent highlights, and large, glossy mandibles.

C.vinctus.face

He didn’t take kindly to being held, but I didn’t give him a chance to bite me.

C.vinctus.jaw.dorsal

He sure tried, though.

C.vinctus.jaw.ventral

He has the standard body shape that I associate with Carabid beetles, a family of mostly large, carnivorous beetles.

C.vinctus.side

In this picture of his underside, you can get an idea of how big he was by comparing him with my fingernails.

C.vinctus.ventral

So, I looked him up in my copy of Beetles of Eastern North America, which starts with the Carabid beetles right in its first chapter.

Based on the brassy highlights, the elongated bumps on his wing covers, and the relative length of antenna segments, I think the best match is the “Round Worm and Slug Hunter”, Carabus vinctus. These overwinter as adults, which is why I found this one immediately after the snow melted. They don’t just eat worms and slugs, but they will take what they can get, and they are commonly active in cold conditions.

One other point about this beetle: after I picked him up, I noticed a strong odor that I thought was reminiscent of dirty socks combined with almond extract. When I got him home and opened the box, the odor was even stronger, and everyone else in the house thought it smelled more like, well, like someone farted. It was quite strong, especially considering that it was just from this little beetle. So if you find one, I don’t really advise holding it too close to your face.

2 Responses
  1. Carole permalink
    May 26, 2019

    Didn’t even know there were carnivorous beetles. Good piece.

  2. June 12, 2019

    I wonder, as he gets older, does it become harder and harder for him to open his mandibles wide the way our muscles get stiff and we become less flexible? Is there mandible yoga for beetles?

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