Black Carrion Beetle Larva and Adult

2015 May 20

Rosie found this beetle larva crawling on the outside wall near our front door on August 24, 2014. It was fairly large, at about 2 cm long (close to 3/4 of an inch). It was pretty fast for a larva, and it would regularly run like crazy, then freeze, which is the sort of thing that makes photographing them kind of annoying.

When disturbed, it would roll up into a ball. It also gave off a somewhat disagreeable, vinegarish smell.

We’ve been seeing these around for years. They are often running across our driveway, or found in the leaf litter under trees, or sometimes under rocks, and on one occasion even in our old house. The last time I photographed one, it was tentatively identified as an American Carrion Beetle, except that the behavior we see is all wrong for that particular species – the larvae of American Carrion Beetles tend to stay with the corpse they are eating, and not run around like free-living predators/scavengers like these seem to.

So, I put it in a jar with some moist soil, leaf litter, and dead bugs to see what would happen, and within a few days it buried itself in the soil and pupated. And on September 7, 2014, it emerged as this jet-black beetle.

From the pattern of ridges on the wing covers and the shape of the head, I believe that this is the Garden Carrion Beetle, Heterosilpha ramosa. This explains why we find the larvae running around in the open: while this is in the carrion beetle family, they are not specialists in feeding on carrion like most of their relatives. Instead, they eat rotting vegetable matter (and maybe the other insects that feed on it), and in some cases will even eat living plants with sufficient vigor to be minor garden pests.

We also appear to be at the extreme eastern edge of their range distribution, they are more of a western species. This would explain why I never saw them in the Lower Peninsula when I was a kid – the species would have been easily able to move into the Upper Peninsula from the west because we connect directly to Wisconsin, but to get into the Lower Peninsula they would have to cross Lake Michigan, and they may well not have done that yet.

7 Responses
  1. May 20, 2015

    Do the beetles retain the memories of events they experienced as larva? I’d think they did. If that’s the case, then they would have learned behaviors inappropriate for their new form. That is, they have the success behavior of a grub, but the body of a beetle.


  2. May 20, 2015

    Wow. Maybe it will be possible to make a strand strong enough for a Space Elevator after all, if they can just work out how to produce enough of the stuff.

  3. Carole permalink
    May 20, 2015

    I may have these in my compost pile. Thanks for the good info

  4. May 20, 2015

    My doctor doesn’t want me to take the Space Elevator. He says it’s better for my health if I take the Space Stairs.

    Sigh. I better get going now if I want to reach geosynchronous orbit by August.

  5. May 21, 2015

    Carole: Thanks!

    KT: If you’re going to climb the Space Stairs, don’t forget your backpack full of butter!

  6. Brittany permalink
    May 22, 2020

    I found a fox carcass in Isabella county teeming with these. I thought they were pillbugs. While cleaning the skull, I found a few in the water afterward and noticed the 6 legs and suddenly was very interested.

Comments are closed.