Bulletin No 29, Winter 2007
Your building has pests. Yes, it really does. Ours does, too. 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, which 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.
1. 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’re preventing the problem in the first place. Here are some of our policies at the Alaska State Museum:
* Eating is only allowed in the kitchen and conference room.
* Eating during receptions is kept in a limited area. The carpet is vacuumed immediately afterwards and trash is disposed of outside the building right after the event.
* Beverages are not permitted at staff desks with the exception of water, coffee or tea in a closed container.
* Collections spaces are kept free of non-collections materials and clutter is not allowed. The cleaner your space, the quicker you will notice something is not right.
* Packing materials are disposed of in the dumpster outside the building.
* No plants or flowers are allowed in the building. None. They are a proven source of bugs as well as food for the bugs.
* Structural gaps in the building are closed with silicone caulk, weather stripping or door sweeps. For rodents, brassy steel wool can plug holes (and doesn’t rust.) Mice can get through spaces the size of a quarter.
* ¼” steel hardware cloth is used to cover floor drains. Rats swim!
* Keeping water drains on the roof clear eliminates many gnats. Usually a hose works fine.
2. Monitoring your populations with sticky traps gives you an early warning of trouble afoot. We order our traps through Insects Limited: (317) 896-9300 www.insectslimited.com The cost is approximately $50 for a box of 100 traps that can be torn into thirds. That makes 300 traps at about 17 cents each. For our three floors and approximately 24,000 square feet, we set about 50 traps. 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. 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 lots of spiders and sowbugs (also called pillbugs) as well as ants, large black click beetles, and centipedes. Google images is helpful, and so are www.bugguide.net and www.museumpests.net. When we find an insect that looks like a “heritage eater,” but we aren’t sure, we put out extra traps in that location for next time and send the trap to the Forest Service for positive identification. We also ask staff to 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.
3. Treatment involves a freezer. Research indicates that our “heritage eaters” can be killed in all phases of their life cycle by one week below -20°C. However, many museums only have access to a frost-free freezer, with temperatures that cycle well above -20°C. 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 must 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 artifacts 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 artifact! 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.
When infestations occur, not only do the artifacts go into the freezer, but the infested space must 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. A recent 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. 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.
An Integrated Pest Management system is part of professional museum practice, just like monitoring your temperature and relative humidity, and keeping your light levels appropriate. 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. Have questions? Call us! Scott Carrlee 465-4806 or Ellen Carrlee 465-2396.
Common Heritage Eaters
1:00 Cigarette beetle
2:00 Drugstore beetle
3:00 Confused flour beetle
4:00 Saw-toothed grain beetle
5:00 Carpet beetle (black, white, and orange)
6:00 Common carpet beetle larvae
7:00 Varied carpet beetle (black, white and gray)
8:00 Common dermestid beetle
9:00 Larder beetle
10:00 Webbing clothes moth (ragged wings)
11:00American spider beetle
12:00 Hide beetle (has white tummy)
Insect debris from L to R: light brown frass and wood bits from a powder post beetle infestation, #2 pencil, larva and striped shed larval casings, soft white cocoons from the casemaking clothes moth.
A dime gives scale to these “harmless” bugs as well as the generally smaller-sized “heritage eaters.”
1:00 and 2:00 spiders are very common and may make webs and nests but eat other insects, not collections. A spider population out of control can be reduced by setting out a large number of sticky traps.
3:00 Minute scavenger beetles eat mostly molds and fungi. These were living in damp plastic bags used to stuff out a mukluk.
4:00 Common weevil, a grain eater.
5:00 Carpenter ants do not eat artifacts, but if you see one, your building itself could be in trouble.
6:00 Common housefly, mostly a nuisance for leaving droppings called “flyspecks” on artifacts.
7:00 Picnic ants are looking for sugar. This one was attracted to a puddle of punch spilled under a printer during a reception.
8:00 and 9:00 Sowbugs or pillbugs come in many shapes and are found in damp areas.
10:00, 11:00 and 12:00 Carabids, click beetles and other large beetles are generally harmless and die soon after coming indoors