DIY Dermestids: Cleaning Skulls the Easy(ish) Way at Home

Dermestids are a family of beetles that feed on dead flesh and detritus. They thrive worldwide as part of nature’s clean-up crew, and they’re a saving grace for the busy taxidermist or bone collector. That holiday starter pack of 200 creepy-crawlies was one of the best gifts I had ever been given–but the surprise element was a little problematic.

With the right setup, a dermestid beetle colony can be a surprisingly low-maintenance method of hands-off cleaning for skull mounts and even full skeletal articulations. Unfortunately, I had no idea what I was getting into when I unwrapped my special present. What followed was a long six months of hard lessons in dermestid ownership, and the first hurdle was housing.

Seasonal timing was a real complication in establishing my colony. I didn’t want my beetles to freeze to death, so keeping them outside wasn’t an option. And while it may be alluring to a dermestid beetle, the aroma of unrefrigerated raw meat is generally unacceptable to humans in an indoor setting.

Without a climate-controlled outbuilding to house them, I had only one option to keep my dermestids alive and their odor contained: my basement utility closet. The space was not nearly big enough for a modified chest freezer, which was the most popular DIY dermestid enclosure I found in a quick Google search. Instead, my first setup was an indoor 40-gallon glass terrarium with a fine mesh top.

I know full well how insane that sounds, but it actually worked through the winter. I was able to grow my colony from a couple hundred to several thousand, and clean dozens of skulls without a bad smell ever escaping the closet. And to my surprise, the smell within the closet was pretty mild.

A big part of stink management was trimming most of the meat off of my skulls before giving them to the beetles, and never giving them more than they could consume within a couple of days. Two more important factors–which I didn’t realize at the time–were ventilation and humidity.

Once spring had sprung and temperatures were holding at a comfortable level, I decided to move my colony into a modified chest freezer in my garage. The build seemed simple–cut a hole in the freezer wall, install a fan, and you’re good to go. But it wasn’t enough.

Two days after I moved the crew into their new abode, something smelled horribly wrong. I opened the freezer lid and was power-slapped by the stench of rot and ammonia. They were the same beetles, on the same bedding, fed on the same ration of skulls. But, they no longer had the climate control of my house, or the free air exchange of a mesh top. The result was a catastrophic buildup of humidity and noxious fumes.

With some extra venting and a dehumidifier running 24/7 inside the beetle house, I was able to reduce the odor to a more manageable level. But I could never get it as tame as it was in the terrarium. Clearly, the mesh lid made a huge difference. That was one feature I just didn’t want to add to the garage setup, because I was scared of flies.

Being neurotic about bugs touching your bugs might seem strange. When it comes to dermestid beetles, this neurosis is warranted. A single housefly has the power to destroy an otherwise healthy and well-kept colony of tens of thousands. This is because maggots–while somewhat similar in appearance to our dermestid grub friends–are filthy, vicious monsters when it comes to keeping dermestids.

When maggots enter a dermestid colony via a fly intruder or egg-ridden meat, they immediately take over by outcompeting the dermestids for their limited rations and multiplying exponentially faster. They also produce more, and fouler, waste than the beetles. You’ll quickly smell the difference, and the unsanitary conditions created by a maggot infestation leave any surviving beetles at high risk of disease.

You might think, “Who cares about maggots vs. beetles if the skulls turn out the same?” The problem is, they don’t. Maggots don’t have the mouthparts to feed on tough, dry flesh and connective tissue like dermestids do. Instead, they gorge on fresh, wet flesh, and leave to pupate as the leftovers harden. Dermestids, on the other hand, are built to deep-clean those leftovers. And that feeding behavior is what creates a spotless product with minimal odor in a captive environment.

While it might seem simple in concept, developing and maintaining a dermestid beetle colony takes some thought and planning. If you get it right, your freedom mounts can look amazing with very little work on the back end. If you get it wrong, which is easy enough to do, then you’ll need to plug your nose, roll up your sleeves, and make some adjustments for a better future with your DIY dermestids.