Why Do Fabric Pests Prefer to Dine on Dirty Clothes?

By Chris Williams on December 23, 2014.

I recently had a bug infestation in several boxes of stored clothes in my attic. Little beetles ate holes in most of the clothes. When I looked for information on the Internet, experts say that you should always wash or dry clean clothes and woolen items before you store them. Why is that? What difference does it make to a bug; sounds like marketing for the dry cleaning industry to me? R. M., Boston, MA 

stored sweaters

Make sure to wash clothes before you store them to deter fabric pests!

The quick answer is that fabric pests need the extra nutritional value that they get from stained fabrics. Most damage to fabrics, woolens, and furs and hides is from just two groups of insects: clothes moths and carpet beetles. These insects evolved as scavengers, feeding in animal nests on feathers, fur, hides, hairs, and dead animals. They also fed on other high protein items like dead insects, pollen, silk, dried meats, grains and seeds. When humans began using these materials for clothing and food, we inherited the pests along with the advancements.

It’s Keratin That They Really Crave

The reason why clothes moth and carpet beetle larvae eat what they do is because they need the protein keratin which is present in wool, hair, fur, nails, skin, horn, and hooves. Keratin is tough stuff and a few insects are the only animals capable of digesting it. As humans, we appreciate this ability since these insects get rid of dead animal carcasses for us by consuming them, from hair to horn. While keratin-containing materials are the main food for the so-called fabric pests, they will also attack other fabrics such as cotton, linen, silk, and even synthetics if the fabrics contain contaminants that supply nutritional value.

By “contaminants,” we’re not just talking about the obvious fabric stains from spilled milk, juice, ketchup, or beer. Insects also get nutrition from the more mundane stains such as perspiration, urine, feces, vomit…you get the idea. In fact, just handling fabric with your hands leaves some oils, skin cells, and debris.

Clean Wool Just Doesn’t Fill You Up

Studies have shown that these pests don’t thrive on a diet of clean wool or fabric because they are missing certain nutrients – mainly minerals, proteins, B vitamins, and salt from sweat. If given a choice between a recently dry-cleaned wool sweater and one that has sweated through three blind dates, and seen at least two seasons of spills from greasy French fries and Big Gulps, a carpet beetle will always choose the second sweater. It’s like a full meal wrapped in a keratin tortilla! Bon appetit!

For more on fabric pests and fabric protection, see these blogs:

Photo credit: Robert Sheie / iW / CC BY

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