'Tis the Season...for Bugs!

by Camille Myers Breeze

It's not usually a favorite topic of conversation, but conservators can always bend your ear about bugs. As spring approaches, dormant eggs hatch, larvae grow and then pupate, and mature adults emerge days or weeks later capable of mating and creating more eggs. And this is when some of our most important work is done.

Casemaking clothes moth damage. Photo courtesy of Museum of African American History, Boston and Nantucket, MA, USA.

Most insect infestations occur in dark and moist areas where plentiful food is available and there is little disturbance. Ideal places include closets, trunks, boxes, plastic bags, suitcases, cupboards, and beneath carpets. You may know you have an infestation because you see the insects or their larvae, but just as often you see only piles of fiber, droppings (frass), webbing, and holes in your textiles.  

Silverfish

Insects choose which textiles to infest based on what the material is. Most textiles fall into one of three categories. Protein fibers are made from animal products and include wool, silk, feather, fur, and leather. Cellulosic fibers come from plants and include cotton, linen, hemp, jute, and paper. Synthetic fibers are mostly man-made polymers, including rayon, a man-made cellulosic fiber.

The most common insect pest that causes damage to cellulosic textile fibers is the silverfish. Resembling a ½-inch-long shark, silverfish are attracted to starch found in food, building materials, paper, and textiles, as well as mold or fungi. They are often found in damp places, such as bathroom linen closets, and are mostly nocturnal. 

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Varied Carpet Beetle

Most structures are home to the carpet beetle, which subsists on protein (keratin). Varied carpet beetles, measuring as little as ⅛-inch long, are the species most common to the US north east. They are oval with a brown and tan striped pattern on their scales. Both the carpet beetle larvae its casing are fluffy and brown. Carpet beetles thrive around dead insects, human and pet food, natural history and taxidermy specimens, carpets, furnishings, and wool or silk clothing. They can be found near warm windows and light fixtures, especially in spring. 

The two most common moths that infest household and museum collections are the webbing clothes moth and casemaking clothes moth. Both are frequent pests on wool and silk clothing, carpets, tapestries, upholstery, and craft supplies. Webbing clothes moths grow up to ⅜-inch long and are pale tan in color. They tend to avoid light, however they can be seen
flying around, especially in spring and summer.

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Casemaking clothes moth and larvae

Casemaking clothes moths are smaller, measuring only ¼-inch long, and may be browner and faintly speckled. The larvae create a silky case and carry it around with them, depositing fiber and frass on it as they graze. The larvae cannot live outside their case. Casemaking clothes moth larvae are just as voracious as webbing clothes moths and will leave holes and large areas of denuded threads.

Despite their similarities, webbing clothes moths and casemaking clothes moths have key differences. The larvae of the webbing clothes moth will eat for 68–87 days, however the casemaking clothes moth larvae can survive as long as 2.5 years before pupating. The adult case-making clothes moth lives a mere 4–6 days, but the webbing clothes moth has up to one month to mate and lay eggs before dying.  

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Webbing clothes moth casings

Casemaking clothes moth casings

If you believe you have an insect infestation, contact a conservator immediately. Do not use pesticides, such as bug spray, moth balls, or boric acid because they are potentially harmful to pets, people, and your textiles. You may carefully vacuum the effected textiles and surrounding areas to remove insects, larvae, and eggs only if you are certain you can do so without damaging fragile fabrics. Quarantine effected items in zip-top or garbage bags and contact a conservator. 

For a more detailed discussion of insect pests that affect textiles, download the latest MTS Handout, Identifying and Mitigating Insect Infestations, from our website.