It was small. Black … with a reddish band across the middle. It scuttled across the kitchen counter on six short legs. I had to swat at it more than once to kill it. It was… a larder beetle.
Larder beetles (Dermestes lardarius) are also known as bacon beetles, and, as you may have guessed, they are frequently found in our kitchens. A member of the scientific family Dermestidae, these insects, while at once creepy and revolting, serve an important function in the world: they clean up messes. That’s right.
In general, dermestids are scavengers, feeding on skin, carcasses, old plant fibers, feathers, dead insects, and so on. They are right helpful out in the wild, but in our houses, they make us wonder about our housekeeping skills. The larder beetle, and its cousin the carpet beetle (there are more than one species) are probably the dermestids most commonly found in your house.
Let’s start with a look at the larder beetle. It is small (a centimeter long at most). It is black at the head and tail ends, with a reddish band running across the middle. Sort of like a woolly bear caterpillar. And it is in your house because there is food there for it: animal-based products. It’s not called a bacon beetle for no reason. Often these insects are found in warehouses, places that store fatty meats (such as bacon), hides, carcasses, etc. Slaughterhouses are probably a good place to look for them, too.
So why do we find them in our kitchens? Most of us don’t have hams hanging in the rafters anymore. If we have meat, it is in the fridge or freezer. Why, I was a vegetarian for seventeen years, and I still had them! What could they be eating? After due consideration, I finally decided it must be the cat (and later, dog) food. But then I read about the larvae. When larder beetle larvae are ready to pupate, they develop prodigious appetites, eating all sorts of household products that would turn our stomachs: wood, cork, paper, textiles, mortar and soft metals, like lead. Well, they aren’t really eating these things, per se. They are actually chewing holes in them to make cozy little dens in which to go through “the change”. Still, they are chewing our stuff. And once they pupate, they are adults, and perhaps it is these newly pupated adults that I am finding in my house.
Carpet beetles, on the other hand, are less fussy – they are simply eating any animal-based product that contains keratin (old fur, old hair, old feathers, old insect parts), although some are also attracted to plants (nectar, pollen). They range in size from one-quarter inch to one inch in length, and they vary in color depending on species. If you have animals in your house shedding away (and what animal doesn’t, with the possible exception of those Egyptian sphinx cats and naked molerats), then your house could be a good candidate for these insects. And the species that like wool can wreak havoc on your precious Persian carpets! One source I found even claimed that carpet beetles can cause allergies, a direct result of our inhaling the shed hairs of the larvae. Ick.
We need to remember, though, that in the wild these insects are really beneficial. They are part of nature’s janitorial crew. Thanks to their yen for skin, fur, feathers, carcasses, we are not surrounded by dead things. Why, they are so industrious that I lost an entire study skin collection to dermestids several years ago (imagine my horror when I opened my collection, which was stored in a wooden wine box, to find nothing left but a pile of dust and wires); they had to be pretty determined to find it. Admittedly, I wasn’t too thrilled, but it is this ravenous desire to consume all things once living that makes dermestid beetles the friends of bone collectors.
Bone collectors? I know, it sounds grisly, but in truth it’s not that bad. There are folks who prepare bones, like animal skulls, for display. I have skulls at home, and many nature centers also have collections. And how do you get your bones to be squeaky clean and suitable for display? You bury them with a bunch of dermestid beetles, who will happily remove all remaining skin, fur, feathers, flesh.
You can cut down on the likelihood of having dermestids in your house by keeping your house clean. Vacuum up the pet hair. Scrub the counters. Keep meat in the cold chest. Make sure everything in the cupboard is well sealed. And if a little visitor should happen to show up (perhaps it pupated in your walls), just scoop it up and toss it outside, where it can feast on nature’s bounty safely beyond your eyesight.
Photo of Larder beetles by Carolyn Klass, Cornell University.
This essay first appeared on the Adirondack Almanack on Oct. 10, 2009.
They love dry cat food. We didn’t have them until we had a cat.
Yes indeedy they do love to be around “feed bins” as well to help clean up any spillage!