Managing Pests in Your Collections

Chicora Foundation, Inc.

© 1994 by Chicora Foundation, Inc. All rights reserved. No part of this publication may be reproduced or transcribed in any form without permissions of Chicora Foundation, Inc. except for brief quotations used in reviews.

Chicora Foundation, Inc.
P.O. Box 8664
861 Arbutus Drive
Columbia, South Carolina 29202-8664

Different Approaches to Pest Management

America's obsession with Rambo-like results and simple solutions, no matter how complex the problem, pervades even pest control. Commercials encourage the public to fear pests (those creepy crawly things) and look to the eliminator (a robo-pest terminator) for immediate, simple, and effective control. Each year millions of dollars are spent on over-the-counter products, professional services, and restricted use pesticides.

And yet we still have pests. In fact, some experts suggest that we are doing little other than creating super-pests, with increasing resistance to more and more pesticides. In addition, we are seeing increasing concerns over indoor air quality, increasing sensitivity to common chemicals, and increasing allergic reactions to a wide variety of products.

The simple truth is that we need to change our way of dealing with pest problems. We need to use less chemicals, make sure the ones we do use are appropriate and that their application is correct, and select the least toxic of the various pesticides available.

At the same time we need to more aggressively pursue mechanical and cultural changes which build or starve pests out, making museums, libraries, archives, and historic sites less attractive to things that destroy collections.

Squirt and Spray Contracts

Many institutions have a contract for monthly spraying. The pest control operator (PCO) comes in like clock work and sprays here and there. But do you know what is being sprayed? Or even why it is being sprayed? Do you see evidence of pests in spite of these treatments? Does anyone on staff accompany the PCO during his or her visits? Do you receive a written statement of the findings and work after each visit?

Too many institutions don't really know the answers to these critical questions. They rely entirely on the commercial company--which may or may not understand the unique value of museum, library, and archive collections--and on the PCO--who may or may not be licensed or even trained to deal with the problems typical of these types of facilities.

Integrated Pest Management

The ideal approach to handling your pest control needs is <integrated pest managment or IPM. But beware--IPM is the "in thing" today and many pest control firms are touting IPM, although what they are offering is little more than that the same old techniques, repackaged to give them glitz. A true IPM program will concentrate on least toxic approaches to pest control by integrating a variety of mechanical, cultural, biological, and (as a last resort) chemical controls.

True IPM will require that your institution develop a program of:

The central theme of IPM is that no single strategy of pest control is likely to achieve adequate results by itself. Control can only be achieved by integrating a variety of approaches. This means combining strategies to achieve a reduction in the immediate annoyance or problem (quick knock-down) with other strategies designed to permanently change the situation so that the problem doesn't keep coming back.

Exploring IPM--Is it Right for Your Institution?

To make the essential components of Integrated Pest Management more understandable, let's go over each issue in detail.

Setting the Threshold Level--How Much Damage is Acceptable?

Perhaps the most difficult step is to set the threshold level--the point at which you implement control. Involved with this is also setting the level of acceptable damage. How many pests of a certain type will be tolerated? Will action be taken for one cockroach sighting, or only when there have been 10? Is one silverfish one too many? Is one rat, one rat too many? Each collection and each setting will likely develop somewhat different threshold levels. For example a modern, well constructed museum may have a lower threshold than a historic site consisting of relatively open log structures. While it is important to be realistic, it is also important not to accept damage to collections as the cost of IPM.

Monitoring--Where and How Many?

Once your institution has determined what can be accepted, and what must result in action, the next step is to begin monitoring. Sticky traps offer the ideal solution to most monitoring problems. These traps have cardboard bases on which an adhesive has been applied and are sometimes called blunder traps since insects "blunder" into them and become stuck. There are also a number of more sophisticated traps, some of which use a pheronome, or attractant, for specific pests.

Placement of traps is essential--they must be located so that pests, if present, are likely to come into contact with them. Just as essential are an adequate number of traps to permit effective monitoring. And traps must be examined at least weekly, with careful records kept of what pests have been found where. Through careful monitoring it is possible to narrow down the source of an infestation, limiting control measures to very specific portions of the collection. Traps which find no pests should be moved monthly to different locations. Traps which are dirty or which have several pests on them should be replaced. Although after the first six months monitoring can be reduced to monthly inspections, the process is constant and on-going. There will never be a time when monitoring isn't required.

Treatment Strategies--Mechanical and Cultural

Integral to the program is learning about the pests you identify and seeking to develop non-chemical methods of control. For example, where are the pests gaining entrance, where are they breeding, what are they eating, where they are hiding? Once you understand the biology and life cycle of the pests you are better prepared to take affirmative actions of mechanical and cultural control--building and starving them out of your collection. Mechanical controls include:

Cultural controls and modifications include:

The Last Resort--Chemical Treatments

Where treatments are necessary, look for the least toxic alternative. For example, when faced with a box of books with silverfish, avoid chemical alternatives and simply hand clean the volumes using a vacuum and a soft brush. When uncertain if pests are active, clean the item, bag it, and examine it several weeks later for signs of fresh activity. Be sure to segregate your collections from new accessions or items with possible pest problems.

The least toxic approach is not only the environmentally friendly approach, but for many collections it is the only responsible approach. Most fumigants will likely affect the long-term preservation of at least some materials. There is no one fumigant which is known to be safe for all collections. Even routine spraying may damage collections through contact with the water or oil based spray. In general pyrethrum compounds are less toxic and less damaging than many other options.

Bringing it All Together

You will likely find that you need to implement a wide variety of control measures--integrating mechanical, cultural, and perhaps some form of chemical control. Each measure should be consistent with the others and should form an overall plan for control.

On the heels of the control program should be increased monitoring to determine if the controls have had the desired affect of reducing, or eliminating, the pest. If the measures have been successful, you step back to the normal monitoring program. If they have not been successful then you re-evaluate the implemented program, identify why the failure occurred, revise the program, and implement new mechanical and cultural controls, again perhaps coupled with chemical measures.

Establishing an IPM Program at Your Institution

Establishing IPM at your facility may not be easy. To be successful, an IPM program requires a lot of "up-front" staff time and training. Of course this time and energy is rewarded later, but some institutions have a hard time realizing the importance, or significance, of these long-term pay-backs. It is also essential that you enlist the cooperation of key members of the staff--especially the janitorial personnel and the building occupants. To provide integrated pest management, the approaches themselves must be integrated. And you can't do this alone--you must have cooperation.

Some institutions may find that with small staffs it is easier to contract IPM out. This can be a successful approach, but the contract manager must have the budget, authority, and some expertise to coordinate the various activities into an integrated effort. And it is still essential to have staff support to make the program work.

Be very cautious when working with outside companies who claim to be offering IPM. Some are not familiar with IPM. Others may say they offer IPM, but don't actually do so because the fee they are charging isn't adequate to cover the necessary monitoring and the various non-pesticide strategies required. Chemical controls are often cheaper and the company may assume that the client isn't sophisticated enough to know the difference. This sort of practice is rare, but you must be willing to pay for all the activities involved in IPM.

The individual components of IPM--inspection, monitoring, injury level assessment, treatment, and evaluation--are typically used by every PCO. Rarely, however, are they integrated or brought together in an organized framework designed to work together to control pests. For example, most pest control firms offer "free inspections." These free inspections, however, undervalue the skills and experience necessary to carry out reliable, comprehensive inspections. Most inspectors also rely only on chemical treatments in response to the problems they identify. For cockroach infestations the typical response may be crack and crevice treatments with a common pesticide. Monitoring and production of written reports are likely to be new steps, unfamiliar to many firms.

Taking Charge--What You Need to Include in a Contract

Consequently, you must set the parameters of an IPM contract with a commercial firm. You will need to specify, for example, the monitoring methods to be used, the frequency of monitoring, and the detail and information in the resulting reports. You may find it helpful to require the use of specific monitoring forms for consistency. Also keep in mind that zero trap catches do not necessarily mean that the pest is absent. It may only mean that the traps are not placed properly. Your agreement with the pest control firm should specify that traps with zero catches are periodically moved to new locations. You should also continue to monitor occupant reports of pest problems, correlating that information with the more formalized monitoring program developed by your PCO.

Developing pest tolerances or action levels may be difficult. There are certainly a number of very good reasons for attempting to approach a zero population number for many pests. Cockroaches and mice, for example, are carriers of numerous diseases. Silverfish and dermestid beetles can cause exceptional damage in museum collections. However, the cost and/or health hazards of exterminating every last individual pest may prove to be prohibitive--this is a decision you should reserve until the monitoring program can be evaluated.

Your agreement with the PCO should also emphasize the need to explore a wide range of control measures, including: education, redesign of the building or its furnishings, habitat modification, maintenance activities, physical control, and (as a last resort) chemical controls. Education efforts might include requests that food not be brought into the facility or that it be kept in only one area, that food residues be better cleaned up, and that trash be disposed of properly. Redesign efforts might include rat-proofing, use of different trash containers, or use of lights less attractive to insects. Habitat modification might include more aggressive caulking of cracks, screening vents, better cleaning procedures, and repair of water leaks. Physical controls include using traps for mice, vacuuming all new collections, and use of silica-gel dusts in voids. Because of the potential health hazards, institutional liability, potential for damage to collections, and public relations problems, chemical controls should not only be a last resort, but should also be very carefully selected. Also, while the initial costs are likely to be low, most chemicals require constant re-application and their real costs are much higher than might be imagined.

The commercial PCO should maintain detailed records of all pesticide applications. Included should be information on the target pest, the product used, the active ingredient of the product, the dilution used, the date applied, the total amount used, where (exactly) the product was used, the individual who applied the pesticide and completed the report, and any additional information which might be important (for example, complaints about the smell, or damage to collections). Require that you be given a copy of label and a material safety data sheet (MSDS) for each pesticide used in and around your institution. The label copy will let you know that the chemical is appropriate for the reported problem while the MSDS will tell you want to do if there is an accident during application or if someone complains that the pesticide is affecting them.

The evaluation process of even a commercial IPM program is essential. The contract manager should examine five areas: the monitoring program itself (Is it reliable? Does it provide the information necessary to make good treatment decisions?), the injury level (Does the level selected provide adequate advance warning of problems? Does it protect your collections?), the treatment activities (Are they successful, i.e., have pest populations declined? Are written records being appropriately maintained?), the integration of services (Is communication adequate? Do all those involved understand how their actions affect the collections?), and the education program (Are staff members receiving adequate information about how to help control the pest problems?).

Because of the difficulties in establishing a truly integrated program, you may be tempted to fall back on the "simple" solution of chemical treatments. Don't give up too easily--you can make a difference by sticking to a well designed IPM program.

But what if your institution really can't develop an IPM program, for whatever reason?

Making the Use of Contract Pest Control Companies More Effective

Even if your institution can't implement an IPM program right now, you can redefine your normal methods of pest control.

Begin by making sure that your PCO signs in every time he or she visits your institution. Not only is this a good security measure, but it will also allow you to better track performance. Have a staff member accompany them--again a good security step and it also re-enforces your involvement in the decision-making process of pest control.

Use a standard sheet for your PCO to identify pest problems and recommended treatment. Let the firm know that from now on you want treatments for real problems--not simply "preventative" squirt and spray visits.

If you feel that "preventative" treatments are essential, have your firm identify products for you that need to be applied less often. While these more effective pesticides are often more expensive, this additional cost should be off-set by the reduced visits. For example, there are insect growth regulators suitable for use with cockroaches that provide excellent long-term control. There are also baits which may provide superior performance to what your institution is using right now. Explore the different options by asking questions.

Begin a dialog with your PCO to identify the cause of your pest problems. A good firm will be interested in working with you to find these problem areas and suggest changes--like taking out the trash more often, keeping the staff lounge cleaner, and removing branches overhanging your building. Most PCOs are genuinely interested in making you satisfied and keeping you as a client--they just need to know that you want a different kind of service. And if your current company can't provide you with what you need, find another firm who is interested in working with you.

For example, if you have a monthly "squirt and spray" contract mentioned earlier, notify the pest control firm that you wish to have them spray only twice-a-year. There are appropriate pesticides which provide this level of kill. Notify the pest control firm that you will need a copy of the pesticide label and the material safety data sheet for every chemical they use in and around your building. Accompany their staff throughout the building. Have their staff provide a detailed written report for each visit, including changes that you should make to reduce the pest problem.

Through even these simple steps you can begin to take control of your pest control problems. Remember that simple solutions to complex problems do not exist and that it is always easier to prevent an infestation than it is to eliminate the pests once they have become established in your collections.

Identifying Pests

There are a number of very good identification sources for common pests, several of which are listed at the end of this pamphlet. With a little practice you should be able to become fairly good with your identifications. Your "tools" should include a few plastic vials for collecting and storing pests, a small tipped paint brush for manipulating small insects, and a hand-lens to better identify your finds. If you find pests which can't be identified using the available references, or you aren't sure of your identifications, most states have a university or college with entomologists on staff. Try calling your local agricultural extension agent to get the name and address.

In addition to the pests themselves, you will often see other evidence of their presence--such as damage to your collections or building, frass (or wood powder) from wood boring insects, staining from rodent raceways, and fecal material from a range of different pests. It is important to be able to recognize these different signs of pest activity since you often may not actually see the pest.

Fumigation and Freezing

In the past many new collections were routinely fumigated using ethylene oxide (ETO)--a very flammable, colorless gas with an ether-like odor. A very effective fumigant, ethylene oxide was used to kill a variety of pests, including mold. As health and safety regulations were strengthened, and ETO's link to cancer was better understood, the use of this fumigant was curtailed. Today it is rarely used and, in fact, should be avoided by museums, libraries, and archives.

In its place have come methyl bromide and sulfuryl fluoride. Both are very toxic and also have associated health risks. Because of its link to the depletion of the ozone layer, the use and availability of methyl bromide is increasingly restricted. Both are also known to affect a range of collections. Sulfuryl fluoride, for example, may corrode metals in its liquid phase and may affect proteinaceous objects, such as leather and oiled skins. Methyl bromide is less safe with objects, affecting paper, leather bindings, and any other material containing reactive sulfur compounds.

If you determine that chemical fumigation is necessary you should make sure that the pest control firm selected is qualified to do the treatment. You should preferably select a firm which specializes in fumigation treatments. You should make sure that they have the testing equipment necessary to determine the concentration of fumigant is adequate and that once vented, the fumigated objects are safe to handle. For fumigation to be effective it is essential to know what pests (and what life stages) are present. Some pests are more difficult to kill than others and almost all eggs are more difficult to kill than either larva or adults. Avoid the "low bid" mentality when dealing with fumigation--the health and welfare of your staff, patrons, and collections are too valuable to be compromised by false economy.

Fumigation offers your collections no resistance to future pest attack. It is essential that once treated, you also take steps to prevent any sort of new infestation from being introduced. This will probably mean taking a variety of steps, such as segregating new (and possibly infested) collections, strictly isolating collections with any signs of pest activity, and improving storage conditions.

Some institutions have selected freezing as an alternative to chemical fumigation. By rapidly lowering the temperature to at least -10 F and holding it at this level for up to several days, most life stages of most insects can be killed. Afterwards, the temperature needs to be gradually increased. While some commercial freezers are adequate for pest control, others are not able to lower the temperature quickly enough. A slow reduction in the temperature allows some insects to go into a state resembling "suspended animation," and survive the treatment. Naturally, it is also important to ensure that the objects are not damaged by the low temperatures and that condensation is controlled.

Recent work by the Getty Institute has developed a safe, effective fumigation protocol using nitrogen--a simple asphyxiant. This is relatively safe for your staff and does not produce harmful effects on collections. This approach, however, requires the use of special equipment and, in some cases, very long exposures. It is, however, worth exploring if your institution needs to treat large quantities of materials or if the materials cannot be safely frozen.

For More Information

If you would like more information about effective pest control strategies these are some sources which may be helpful:

Developing an IPM Program with a commercial pest control firm:

Olkowski, William and Helga Olkowski. 1989. Contracting for Pest Control Services. Berkeley: Bio-Integral Resource Center.

Pesticides, People, and the Environment:

Briggs, Shirley. 1992. Basic Guide to Pesticides: Their Characteristics and Hazards. Washington, D.C.: Hemisphere Publishing.

Pesticides and Your Collections:

Dawson, John. 1988. "The Effects of Insecticides on Museum Artifacts and Materials." In A Guide to Museum Pest Control, edited by Lyndia A. Zycherman and J. Richard Schrock. Washington, D.C.: Association of Systematics Collections.

Dawson, John and Thomas J.K. Strang. 1992. Solving Museum Insect Problems: Chemical Control. Technical Bulletin 15. Ottawa: Canadian Conservation Institute.

Identifying Common Pests:

Christensen, Chris. 1989. Technician's Handbook to the Identification and Control of Insect Pests. Second Edition. Cleveland: Franzak and Foster.

Kinsolver, John M. 1988. "Illustrated Guide to Common Insect Pests in Museums." In A Guide to Museum Pest Control, edited by Lyndia A. Zycherman and J. Richard Schrock. Washington, D.C.: Association of Systematics Collections.

National Pest Control Association. 1986. Wood Destroying Insects' Manual. Dunn Loring, Virginia: National Pest Control Association.

Robinson, William H. n.d. Determining Active and Inactive Infestations of the Old House Borer and the Powderpost Beetle. Dunn Loring, Virginia: National Pest Control Association.

Pest Control "Bibles":

Ebeling, Walter. 1975. Urban Entomology. Berkeley: University of California, Division of Agricultural Sciences.

Mallis, Arnold. 1982. Handbook of Pest Control. Sixth Edition. Cleveland: Franzak and Foster.

Sources of Pest Control Supplies:

Most chemicals suitable for use in museums, libraries, and archives are restricted use pesticides, meaning that they can only be sold to and applied by licensed PCOs. Monitoring items, such as sticky traps are widely available. You should try your PCO first. If they are unable or unwilling to supply your needs, contact Chicora Foundation and we will recommend alternatives. Insects Limited, Inc. (800/992-1991) is a company which provides pheromone traps and insect attractants. Agrisense (209-276-4250) also provides sticky traps and pheromones.

Chicora Foundation provides free telephone consultation. You may reach us at 803/787-6910. We also provide for-fee consultation on pest control strategies and developing IPM programs. While several of our staff are licensed in structural pest control and fumigation (in South Carolina) and we review the recommendations of commercial pest control firms, we do not perform treatments.

Figure Omitted

Physical Characteristics of Typical Fecal Materials

Courtesy of J.T. Easton & Company, Inc.

Major Differences Between Winged Ants and Termites

Note Antenna, Wings, and Body Shape

Figure Omitted

Key to Identification of Woodboring Beetles from Exit or Entry Holes










Structural timber, logs



Ambrosia beetles



New, Old

Molding, flooring, furniture

Fine, flour-like, loosely packed


Lyctid beetles


Wood with bark on surface


Structural timbers, logs

Coarse, bark-colored


Bark beetles



New, Old

Crawl space timbers, flooring, furniture

Fine powder & pellets loosely packed in softwood, no pellets & packed in hardwood


Anobiid beetles


Hardwood, Bamboo


Molding, flooring furniture

Fine to coarse, tightly packed


Bostrichid beetles


Softwood, Hardwood


Structural timber, logs

Coarse to fibrous or absent


Cerambycids (sawyers)




Structural timber, logs

Sawdust-like, tightly packed


Buprestids borers (flatheaded)



New, Old

Structural timber, siding, logs

Very fine powder, tiny pellets tightly packed


Oldhouse borer


What is Chicora Foundation?

Chicora began as a small, not-for-profit, public foundation over a decade ago, with the lofty mission of preserving the past for future generations.

Today that means a wealth of innovative programs. All are focused on the realization that museums, libraries, and archives must maximize the benefits of limited preservation and conservation funding. We work with your team to provide practical, cost-effective solutions for your complex problems.

Chicora Foundation is a leader in offering a wide range of preservation services, including on-site consultations, workshops and seminars, and telephone consultations. Our areas of expertise include the care and handling of collections, preservation assessments, preservation planning, integrated pest management, environmental monitoring and controls, fire safety, and disaster planning.

While our telephone consultations are free, more in-depth consulting is offered on a for-fee basis. For more information on our services and the associated costs, call us at 803/787-6910.

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