Fun Facts About Museum Pests - Part 2 | Minnesota Historical Society

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Fun Facts About Museum Pests - Part 2

By: Megan Narvey | Conservation | November 3, 2020

In Part 1 of this series, we talked about the common clothes moth. Today, I'd like to tell you about my favorite museum pest. When I say favorite, I definitely don't mean that this is the best kind of pest to find in your home or your collection. They're not easy to detect, can be very difficult to eradicate, cause a lot of damage, and can live basically anywhere! However, when they’re not ruining your wool rug, they have been put to good use in some professions. And the larvae have the best nickname of any museum pest. Today, let's learn more about the carpet beetle!

Multiple life stages of a carpet beetle.
Clemson University - USDA Cooperative Extension Slide Series, Bugwood.org

Carpet beetles are a type of dermestid, also sometimes referred to as “skin beetle”.
Some types of dermestids are really helpful. Forensic entomologists use them to learn more about criminal investigations, and taxidermists and natural history museums use them to clean animal skeletons.
A carpet beetle is the same shape as a ladybug, but much smaller - only a few millimeters long! They are usually black or a mottled yellow, black, and white.
Adult carpet beetles feed on pollen, so it's easy to accidentally introduce them to your home or museum by bringing in fresh cut flowers. They can also fly, and enter through open windows.
Another common source of infestation is having bird or wasp nests on your building.
Even though adult carpet beetles prefer to live outside, they like to lay their eggs inside. Female carpet beetles can lay about 50 eggs.
The larval form are called “woolly bears” because of their densely packed hairs.
The late stages of woolly bear growth can be up to twice as big as the adult beetle!
Just like with clothes moths, these cute little fuzzy larvae are the ones responsible for damage to the collection.
Woolly bears feed on wool, fur, felt, silk, feathers, skins, and leather, and they’re more likely to be found in dark, undisturbed areas. However some will also eat things like seeds and grains; and they will eat through other materials if a food source they want is nearby.
Some woolly bears can live for up to two years if the conditions aren't ideal for them to grow and pupate!
As woolly bears grow, they shed their skins. These shed skins are one way to identify that you have a carpet beetle infestation.
Another good way to identify a carpet beetle infestation is on your window sills. Adult carpet beetles are attracted to light, and often congregate near windows.

The best way to prevent a carpet beetle infestation is through housekeeping and integrated pest management. If you spot a carpet beetle or woolly bear on your collection, it's usually a good idea to bag that item right away. Many museum objects are safe to freeze if following the proper protocols, and this can kill carpet beetles, woolly bears, and eggs. Always consult a conservator if you're not sure whether a treatment method will be safe for your collection.