Dermestid Beetles Cleaning Deer Skulls

2015 July 8

Last fall, Sandy shot a deer that had quite a nice set of antlers, good enough that she wanted to go ahead and mount it properly. It turns out that there is a taxidermist up in Calumet who prepares “European mounts”, which is a mount of just the skull and antlers, no skin. And in order to get the bones completely defleshed, without missing any little crevices, he has a big colony of dermestid beetles to do the job. And, he let me get some pictures. Here is a skull that they were working on at the time:

They had finished the top, but when we turned the skull over, the beetles and grubs were still working on the bottom:

I think these are Hide Beetles, Dermestes maculatus, a European species that is widely used by museums and taxidermists for bone cleaning. While any of the Dermestid species would probably work fine for this (like Carpet Beetles or Larder Beetles), these particular dermestid beetles are larger than average, grow fast, and can devour a lot of flesh in a fairly short time.

The colony was being maintained in a big plastic storage tub, with a layer of styrofoam in the bottom. When they weren’t consuming flesh off of the skulls, the beetles and larvae were burrowing into the styrofoam.

Here’s a single grub, with its head into the styrofoam but its body well exposed:

It looks like one of the functions of the hairs might be for camouflage. This grub was completely covered in styrofoam crumbs that look like they were being mostly held in place by the hairs.

Anyway, here’s the finished, mounted skull. He bleached it for whiteness, but otherwise the cleaning was done by the beetles.

And here’s a closeup of the delicate nasal bones. These bones are almost paper-thin and easily damaged, but the beetles cleaned off all of the flesh while leaving the bones completely intact.

While in this case they’ve been domesticated to serve a particular purpose, these beetles can easily become pests in certain circumstances. While they are good for cleaning up bone, they will destroy skins and furs that a taxidermist might be intending to preserve, so one wants to keep the beetles well-confined to the bone-cleaning room. If they get loose in a house, they would eat anything that carpet beetles eat, like leather products, animal-based fibers like wool, and various kinds of preserved foods. Which is one reason why you probably want to do this sort of work in an outbuilding, and not in the basement of the house you are living in.

3 Responses
  1. July 8, 2015

    Isn’t it kind of unusual for beetles to eat things like leather? I thought they needed their food pre-digested to some extent.

  2. July 9, 2015

    It’s a bit unusual for *anything* to eat things like leather, yes. The proteins in it are pretty indigestible. The dermestids have made something of a specialty of eating things rich in keratin and collagen (hair, feathers, and skin, mostly) that most other animals can’t easily digest. They’re basically tackling what’s left over after the other carrion feeders have given up.

    Since beetles are probably the most diverse group of animals on the planet, it’s hard to make generalizations about what they eat. For any given material that is even theoretically edible, there is probably at least one species of beetle that is willing to take a shot at eating it.

  3. July 13, 2015

    Something you no doubt already knew:

    “(They) have enzymes in their digestive tract which digest keratin. This makes them very unusual in the animal world.

    Sometimes dermestids can help with criminal investigations. Forensic entomologists will look for dermestid beetles at crime scenes when trying to determine the time of death. Dermestids generally show up late in the decomposition process, when the corpse begins to dry out.”

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