By Tom Strang
This article was published in Museum News July/August 2005.
You have pests? First, get over the feeling of being stigmatized. Most museums have pests at one time or another; some have them all the time. You can either live with them and hope for the best, or you can fight them off. It really is your choice as the current caregiver of your collections. Given what you know about the pests’ behavior, where you find them, and their numbers, you think you need to do something? Good. With that information you are probably drawing a correct conclusion. How far have they spread? You can’t tell for sure? That is common. You have several methods for cleaning up the objects you know are infested, and that will take a bit of effort to do properly. What do you do after that? Do you want to avoid being blindsided by another little crisis like this again? If so, your museum should implement Integrated Pest Management (IPM).
The term “Integrated Pest Management” was coined to refer to a method of pest control that integrates knowledge in developmental biology of agricultural pests with effective timing of response methods. The original goal was to find the lowest-cost, highest-return (yield or quality) farming production model for agricultural crops. It’s most significant contribution has been to reduce pesticide use from a broadcast prophylactic to a more effective tactical application. The concept adapts beautifully to museum pest control. In collections care, we integrate several modes of action to reduce pest pressure on stored objects. We learned these lessons from a wealth of experience developed in the field of stored food products, as well as our own work with collections.
IPM is a layered approach that tries for the greatest hazard reduction with available resources and effort. Unlike farms, museums are not always driven by hard-nosed “lowest cost” economics in each decision because of the tangible/intangible values of our collections, which, ethically, we avoid compromising. But as a profession we generally don’t have a lot of money to throw around so we try to be sensible in allocating resources. IPM helps us make these choices wisely and also tries to increase what we know about pest activity. This information either reinforces our comfort or heightens our awareness of hazards. To do IPM well we need actions to forestall disaster (save resources) and to decrease the number of actions needed to curtail disaster (restrict losses).
You have a choice between “pro-active management” and “crisis management” (to use buzzwords) as endpoints to the question, “When do I act . . . before, now, or later?” Avoiding pest hazards and blocking them are all about trying to be “pro-active,” meaning we take some action about serious things before the worst happens. This requires a sensible model of predicting the future outcomes from your present actions. An accurate model requires a systematic survey of our facilities. This survey can produce straightforward reactions to obvious situations. (“Oh, the rain gutter is dumping against the foundation, maybe that is why we have so many damp-loving book lice. We should fix that someday soon.”) Indirect connections (indirect to us anyway) are tougher sells but by noticing coincidences, you have somewhere to start an examination. (“You remember the cleaning staff hours you cut back on sir? Well the bugs are taking over their jobs in the back hall.”)
Proactive management includes minimizing hazards from pests by reducing the frequency and intensity of the pest interaction with objects. This creates the outermost shell of preventive conservation. For example, we enforce basic sanitation. Why? Because it reduces the ability of pests to find unseen harborage, food, and water. Don’t leave the interior lights on all night near a hole in the wall (leaky door or window). Clean up long-term clutter and other such situations that draw pests inside. By “pushing back” in this way some pest hazards are reduced. Even if one is using pesticides indoors, basic sanitation is a prerequisite of their effectiveness; if pests are forced to roam further for sustenance, they’ll take the baits, bump into the traps, touch the sprayed baseboards, and die.
Another control method is block the pests. Without barriers to movement, your entire collection may as well be outside in the field or forest. Containment is useful for many reasons: protection from outdoor weather, fire safety, refining the interior environment—including reducing pests. There is a trade-off; putting objects into closed containers hides any pest activity “behind closed doors.” Create effective inspection methods that match your level of containment. If you know the containers are reasonably pest resistant (tightly sealed doors, polymer bags, tight-lidded containers), the objects were pest free before they went into the containers, and you have done nothing to compromise the situation, then you are justifiably less stressed about detection. Reverse any one of these conditions, and you ought to take a look now and again.
When prevention fails or you are handed an infestation (the proverbial Trojan horse) you are in crisis-management mode. Protect yourself by detecting the pests and then responding. Managing big pest infestations is all about ensuring effective suppression. Picking an appropriate method, making adjustments to ensure the technique works, etc., are all important skills to have, take experience to gain, and objective measurement to confirm. Beginning with understanding of the pest’s biology, behavior, and susceptibilities we often can modify the situation to lower the pest’s success (including avoid and block responses) or kill it outright.
However, it is still a hazard and risk game. (If I treat with X, I attack the ozone layer; if I treat with Y, I wait three times longer with people yelling at me for the objects. Which is better?) Any risk from treatment methods are balanced against the hazard posed by the pest. Consider the use of arsenic in collections—it has moved from a widely used stalwart preserver to a manageable health risk. Or consider the removal of pesticides from our food chain and the restriction on using ozone-depleting fumigants, methyl bromide in particular. We are constantly readjusting our perceptions of acceptable pest-control practices based on increased knowledge and recognition of downstream effects.
Fortunately, we now have a number of nontoxic or low-toxicity options for pest control in collections. We can use low temperature, below 20ºC for a week or more to kill insect pests; moisture-resistant bagging and careful handling of the objects prevents most hazards. We use controlled atmospheres (an agricultural term) to asphyxiate insects. Carbon dioxide and low oxygen are the two most common, and we can use these on a large or small scale, adapting to delicate collections or sheer industrial volume to be treated. We use heat to kill insects, from treating whole buildings treatments to using a small oven. This gives us a fast and certain kill, and with bagging or engineered humidity control very delicate objects are not appreciably affected by the process. We use traps and limited bait deployment to kill rodents, but must combine this activity with blocking for it to be effective. We use pesticides, but where human health concerns are high we use tactical approaches like baseboard sprays, and this often is where they are most beneficial and cost effective. We reduced the use of preventative chemical fogging of collections. All treatment methods can be hazardous; nothing is foolproof because fools are so ingenious. But we have a lot more knowledge and professional comfort in these methods now than we did 15 years ago. Early adopters in our profession took managed risks and demonstrated the way for others. Find colleagues with experience in pest management; talk to them, and share your experiences.
Determining an appropriate response is difficult at times when you do not know the extent of the hazard. When the problem is obvious and well contained, this is not difficult. (“Thanks for the moth-eaten fur stole. We’ll just pop it in the freezer for now.”) It helps to enlist all museum staff in this effort. Early on in your IPM process, involve the staff, including cleaners and security, and increase their concern to such a reasonable level that they accede to sensible pest-control requests: “Please remove garbage promptly. Please inspect and allow treatment for pests before putting new material in collection storage.” They’ll also give you information: “You know that farming exhibit? I saw something crawl under the grain bags.”
Integrating pest-managing activities into our work and pest-managing structures into our workplace buys us more time over the long term. Time for the objects to entertain and inform us. Time for us to enjoy a more healthy life by reducing our chronic exposure to toxins. Time to do other tasks that our paying public can appreciate.
Tom Strang is senior conservation scientist, Canadian Conservation Institute, Department of Canadian Heritage, Ottawa. This article is excerpted from Covering Your Assets: Facilities and Risk Management in Museums, edited by Elizabeth E. Merritt and published by AAM in April 2005.
