Your building has pests. Yes, it really does. Ours does, too. If your building has no bugs at all, that means it is toxic. A small resident population is normal. But are they a threat to your collection? With an Integrated Pest Management (IPM) system, you can be active in your prevention of infestation and effective in your response if one occurs. In the past, museums would respond to evidence of an infestation with poisons. Many of those substances are now illegal, some contaminated or damaged the artifacts, and most were dangerous to museum staff as well. Museums took a cue from the agriculture industry, who needed to control bugs on stored grains without contaminating the food with toxins. An IPM system uses good housekeeping to keep pests out, traps to monitor the presence of bugs, and low temperature to treat infestations.
Good housekeeping aims to keep the pests out in the first place. If you can avoid carrying in new pests, prevent them from entering the building from outdoors, and reduce things that attract them, you preventing the problem in the first place. Here are some of our policies at the Alaska State Museum:
Monitoring your populations with sticky traps gives you an early warning of trouble afoot. We use Trapper Monitors (fig. 1-2) through Insects Limited. They are also called “blunder” traps, so place them where a bug is likely to stroll in. This includes along the wall, near sources of water like drains, and next to doorways. Number each location on a map, and label each trap with its number, location and date. Change the traps every three months, and keep a chart that describes what you found in each trap. This task usually takes about 3 hours at the ASM. Longer intervals between trap checks risks loss of data from other insects eating the dead ones. Finding evidence of a bad bug earlier in an infestation can make response much easier. If you take a flashlight, checking those dark corners for rodent droppings or other debris is also useful.
Our traps at the Alaska State Museum usually contain routine spiders and sowbugs (also called pillbugs), ants, large black outdoor ground beetles like carabids or click beetles, and centipedes. Tiny pests you can barely see include psocids (booklice) with a rounded shape and teeny spiky-looking springtails. Google images is helpful, and so are the websites bugguide.net and museumpests.net. Size can be helpful in identification. Here are some images of good and bad bugs compared to a dime (fig. 3-4).
Figure 3: Common bad bugs are arranged around this dime like a clock:
Figure 4: Common harmless bugs are arranged around this dime like a clock:
When we find an insect that looks like a “heritage eater,” but we are not sure, we put out extra traps in that location for next time. In the past, we’ve sent traps to the Forest Service of the Cooperative Extension for help. We also ask staff to gently catch any bugs they see on a piece of scotch tape. Anything that was originally a plant or animal has potential for insect infestation. At the top of the list for tasty bug treats are fur, feathers, leather, and wool.
Larger pests like mice, squirrels, and woodpeckers sometimes attack museum collections (fig 5-6). Mice are often strong enough to escape a paper blunder trap, but will leave evidence like droppings, fur, or chew marks. Snap traps are usually the response, using peanut butter, cheese wiz, or a pine nut as bait (fig. 7). If the bait is gone when you check, that is evidence you’ve got a smart mouse. Bait that is not taken suggests the mouse may no longer be in the building.
Over the past 20 years, the Alaska State Museum has resolved or assisted other institutions with infestations of the following creatures: mice, clothes moths, spider beetles, minute scavenger beetles, picnic ants, carpenter ants, dermestid beetles, powderpost beetles, and booklice. Sometimes we see evidence of insects without seeing live ones (fig. 8-10).
Treatment to prevent and respond to insect infestation involves a freezer. Research indicates that our “heritage eaters” can be killed in all phases of their life cycle by one week below -20°F (-29°C). However, many museums only have access to a frost-free freezer, with temperatures that cycle well above -20°F. Many insects are “frost tolerant” and can make a substance like antifreeze to survive a dose of cold. But our brains are bigger! The artifact can be placed in the freezer for a week, then removed and allowed to reach room temperature for 24 hours, and put back in the freezer for another week to deliver a deadly second round of cold. It is very important to package the artifact properly for low temperature treatment. You should wrap the artifact in a soft absorbent material such as plain tissue paper, white paper towels, or a soft cloth. This helps protect it against both the increase in relative humidity at lowered temperature and the slight increase in brittleness when things are cold. Then, the artifact needs to be placed in a plastic bag that is well sealed. Squeeze as much air from the bag as you can and seal the Ziplock or use a heat sealer if possible. Lucky for us, most museum objects don’t have enough water in them to create ice. However, upon removal from the freezer, condensation will form, and it is much better for that moisture to form on the plastic bag than on your object (fig. 11)! After a day of adjusting to room temperature, you can safely remove your artifact from the package. Removing all the old bug debris is a good idea, so any future bug debris will be a clue to a new infestation. Brushing the debris into the nozzle of a vacuum cleaner with a soft paintbrush usually does the trick, or it can be delicately picked off with a tweezers.
When infestations occur, not only do the artifacts go into the freezer, but the infested space should be vacuumed, carpet steam-cleaned, and the perimeter of the area dusted with boric acid. Occasionally, it is necessary to turn to bait. Ant traps and D-Con are examples of bait, which are not pesticides but kill the pest through mechanisms like thinning the blood to induce internal bleeding. Bait typically kills much more efficiently than traps. An infestation of picnic ants at the Alaska State Museum was controlled with ant bait that was carried back to the nest.
Many museums do preventive treatment of incoming artifacts with the freezer. A donation of a fur parka, for example, would definitely go in our freezer before it went into our clean collections room. What if you don’t have a freezer, or the incoming artifact is too big? Careful visual inspection in dark crevices can help set your mind at ease. Look for holes, loose hair, bald patches, live bugs, bug parts, cocoons, webbing, bug nests, and tiny bug droppings known as “frass.” Frass is round, so suspicious-looking dirt can be sprinkled on a piece of paper and the paper tilted…if it rolls easily, it might be frass. If you don’t see this evidence, the next step is to lay the artifact on a pristine white surface and place some sticky traps around it. Seal it in a plastic enclosure to prevent anything from walking away and infesting your space. Wait two months or so to allow any eggs to hatch and get active. If you see no debris on the white surface and nobody in the sticky traps, you’re probably safe. Preventive treatment is also done with items for sale in the Alaska State Museum gift shop.
Publication describing risks of putting collections in the freezer:
An Integrated Pest Management system is part of routine professional museum practice, just like monitoring your temperature and relative humidity, and keeping your light levels appropriate for each exhibit. Dealing with an infestation after it happens is upsetting, time consuming, difficult, and often means irreversible damage to museum collections. An ounce of prevention is truly worth a pound of cure.
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Questions? Contact Us! The Alaska State Museum has an outreach mandate to help provide advice and expertise to museum professionals and other caretakers of Alaskan material culture.
Email Ellen at ellen.carrlee@alaska.gov or fill out our online contact form.
