A Pest Smorgasbord at the Library: Paper Grazers and Leather Eaters

Monday, March 27, 2017

Preservation of collections often includes some element of risk management: monitoring a storage area can help head off disasters like leaks or insect invasion.

Integrated Pest Management (I.P.M.) is the term for ongoing monitoring of an area to curtail or prevent damage from insect or invertebrate pests. Winterthur Museum Garden and Library recently held a two-day workshop on I.P.M. for museums and libraries, called “Stressed About Pests?”

Bug eaten fur hat
Participants at a recent pest management workshop at Winterthur examined items damaged by insects, including this fur hat eaten by moth larvae. By observing the damage and residues left behind, the suspects were identified.

This program turned out to be both fascinating and repulsive, especially with teaching material that included a preserved bat specimen and intimate beetle and moth videos.

Use of insecticides is discouraged by the I.P.M. community. Instead, the behavior of pests is studied to see what types of situations invite them in and allow them to thrive.

Sticky “blunder” traps are set out in a strategic pattern along walls, and near doors and windows to get a sampling of the bug population. These traps may snag the random millipede or spider interloper. They may also find recurring groupings of museum pests, which can help identify a burgeoning threat.  

A better understanding of the specific pest enables preservation staff to make library spaces less welcoming. One way to do this is to eliminate eating in collections storage and use areas. Food and drinks consumed near collections leave residues that draw bugs that may also eat paper, leather bookbindings, or natural adhesives.

The workshop instructor shared an example of a Hershey’s kiss stored in a desk drawer (still wrapped!) with holes made by an insect pest. That pest had become numerous enough to be noticed in traps around the institution.

Another interesting story involved the purchase of some folk art natural plant “flutes” as museum store merchandise. Instead of delivering sweet music, they brought along wood-eating beetles!

When a new collections item is acquired it may be advantageous to seal it in clear plastic and to monitor it to make sure that no pests are residing within.

One useful tip is to place white tissue paper beneath objects, making frass (insect poop) and powdering from active damage more evident. If activity is found, it may be appropriate to freeze the object to kill the bugs. (Note: most regular home freezers may not be cold enough to kill bugs; one prescribed condition is -22 F for 72 hours).

As a program participant, I learned to identify some of the most worrisome insect threats to cultural heritage. Some of the insects that do the greatest damage are excruciatingly small, so it takes a keen observer to pick them out, and a good microscope to positively identify the critter.

Buffalo carpet beetles, for example are only about the size of a sesame seed. They belong to the Dermestidae family whose larva consume proteinaceous materials like hair, wool, silk and fur. Carpet beetles breed on flowering plants, so they may be transported into museums via flower bouquets. 

Another important thing to remember: The only good pest is a pest that is securely swept up in a vacuum cleaner! (Housekeeping is important.) Bug carcasses left alone may invite other pests who feed on the dead!

Many thanks to Winterthur and the facilitators of the workshop: Rachael Perkins Arenstein, Patrick Kelley and Matthew Mickletz.


Laura Wahl is the Library Conservator at Hagley Museum and Library.