ICOM Ethnographic Conservation Newsletter
Edited by Anthropology Conservation Laboratory, Smithsonian Institution 

Newsletter Index 

Number 15 ISSN 1036-6210 April 1997

Table of Contents

Note from Your Editors:

Technical Exchange
New Termiticide
Upcoming Workshops

Museum and Native Peoples Issues
Pest Management at the National Museum of the American Indian

Laboratory Highlights
Conservation at the Fiji Museum

Integrated Pest Management: Just for the Big Guys?
Managing an Outbreak of the Webbing Clothes Moth (Tineola bisselliella): A Case History
Integrated Pest Management and the Odd Beetle
On Freezing of Objects
The Integrated Pest Management Program at the U.S. National Park Service, Division Of Conservation, Harpers Ferry Center

Newsletter inquiries and contacts


We are very pleased to devote this newsletter to the issue of pest management. The topic evolved as our initial contributions presented discussions on this subject, and we then proceeded to request specific articles relating to the topic. The range of articles addresses Integrated Pest Management, specific pest infestations, and freezing of collections as a method of pest control. We are also pleased to include a Laboratory Highlights contribution from the Fiji Museum.

Our mailing list currently includes over 800 subscribers, and we continue to receive requests for the newsletter. This newsletter issue will be sent to all 800 subscribers, but in a effort to cut costs and workload, beginning with the next issue (October 1997) we have decided to send one newsletter per institution, instead of multiple copies each addressed to an individual within the institution. This measure will reduce the number of newsletters by half. Everyone else will receive the newsletter as usual. If this presents a problem to anyone, please let us know immediately.

Special thanks and recognition go to Carole Dignard, a Regional Coordinator from Canada, who has provided us with contributions from her region for the last two newsletters. It is no easy task to find people and articles, and she has not only done that, but also worked with the authors and with us to ensure contributions that are timely, appropriate, and worthwhile to the readership. In addition, this issue has benefitted from the discerning eye of our third year intern, Linda Lennon, whose contributions towards editing were invaluable.



The Southern Arizona Division of the Arizona Historical Society is trying a new chemical control method for an infestation of subterranean termites. Licensed for use as a pesticide in Arizona, PremiseŽ 75 is a promising new product from Bayer Corporation. Five years of study in Japan and four years in the United States convinced at least one commercial termite control company that Premise should be used exclusively in post-construction termite eradication. The following information is excerpted from the product literature provided by Bayer Corporation.

Imidacloprid, the active ingredient, is a nicotine derivative in a concentrated powder form. This water-soluble chemical is sold only to professional pest control operators who dilute it and inject it to create a continuous chemical barrier between the wood in the structure and the insect colonies in the soil. Premise has extremely low vapor pressure, which means there is virtually no airborne vapor during and after treatment. It requires less chemical active ingredient to control termites with Premise than with other termiticides. Based on the recommended dilution rate of 0.05%, Premise has a concentration rate 2.5 to 5 times lower than currently used pyrethroids and 10 to 20 times lower than currently used organophosphates. In addition to applying a liquid termiticide to the soil around and beneath a structure, pest control professionals also rely on termiticide foam to treat hard-to-reach areas. Increased concentrations of Premise can be applied as foam at low surfactant rates to treat areas such as wall voids, voids under slabs, dirt-filled porches, and along window sills. The foam is pumped into these hard-to-reach areas where the termiticides can easily spread.

Unlike other termiticides that create chemical barriers, termites cannot detect the treated zone of Premise, and will forage into it. As soon as there is contact with Premise, termites are affected; Premise affects specific sites within the termite's nervous system. Premise carries the EPA signal word "CAUTION" which is the least toxic pesticide category but protection for eyes, hands and skin are needed by applicators. Use of Premise presents low risk to people, pets and the environment. But, because of its soluble nature, Premise may not be applied to areas where surface water or underground wells are present. At this point, pest control operators are conservative in guaranteeing the effectiveness of the product for about four years. Obviously there is still no conclusive means of eradication of subterranean termites but PremiseŽ 75, by itself or possibly in conjunction with bait monitors, is a low-toxicity option. For more information call Bayer Specialty Products at 1-800-842-8020 or refer to web site:


Laraine Daly Jones
Arizona Historical Society
949 E. 2nd St.
Tuscon, AZ 85719


Conservation and Care of Indigenous Peoples Cultural Materials
Whitehorse, Yukon, Canada
May 25 -31, 1998

This workshop, planned in conjunction with the annual conference of the Canadian Association for Conservation of Cultural Property, will address issues involved in the conservation of indigenous people's artifacts in collections across Canada and around the world. Topic suggestions are: training, care, repatriation, conflict resolution, direct collaboration between conservators and First Nations communities regarding treatment options, and the integration of First Nations traditions care and practices into standard care of collections procedures.

If you have any suggestions regarding other topics or would be interested in presenting at the workshop, please contact:

Diana Komejan
Yukon Tourism - Heritage Branch
P.O. Box 2703
Whitehorse, YT
Y1A 2C6 Canada
Tele: 403-667-3431; Fax: 403-667-8023; E-mail: dkomejan@mail.klondike.com

Anoxic Enclosures and Microenvironments in Museum Storage and Exhibits
Intermountain Cultural Resource Center, National Park Service, Santa Fe, New Mexico
May 19 - 22, 1997
Yale University Museums, New Haven, Connecticut
September 23 - 26, 1997

The workshop will focus on creating, monitoring, and adapting a variety of microenvironmental systems for use in treatment, storage, and exhibition. Topics to be addressed include:

Course fee: $300

For more information contact:

Sally Shelton
San Diego Natural History Museum
P.O. Box 1390
San Diego, CA 92112


Leslie Williamson

Editors’ Note: This article briefly discusses culturally sensitive artifacts in the context of pest management. The issue of care and handling of culturally sensitive material is a very pertinent one and the editors would like to broaden and pursue the topic in our next newsletter if such interest is reflected by submissions from our readership. The experiences of conservators and others involved in development of protocols and treatments for such objects would be helpful for all concerned with this important issue.

As this may be a concept unfamiliar or relatively new to some of our subscribers, we thought it might be helpful to have the phrases "culturally sensitive" and "qualified caretaker" used in this article defined. The author declined at this time, so we asked Smithsonian staff anthropologist, Chuck Smythe of the Department of Anthropology Repatriation Office, to give us general definitions. He describes culturally sensitive objects as those that may be considered to be of special significance in a particular culture. In many cases these objects are believed to be, or have been in the past, spiritually active or possessing spiritual power. Objects used by shamans, for example, may retain some of the power they were endowed with at the time of their use. Other examples of culturally sensitive objects are those that are used exclusively by men and for which handling by women would be culturally inappropriate. He describes a qualified caretaker as an individual who knows the culturally prescribed rules for handling and maintaining culturally sensitive objects. In some cultures, the caretaker has the responsibility for keeping the artifacts safe on behalf of a larger group until they are passed on to subsequent generations, i.e., another caretaker.

At the National Museum of the American Indian, our pest management goals are to ensure the safekeeping and longevity of the collection by following standard museum procedures, and to respect and promote culturally based care systems. Methods of pest management employed in our storage and exhibition facilities follow current standards of integrated pest management. We have a regular routine of monitoring and housekeeping, and any problem areas are dealt with by immediate cleaning and increased monitoring. Continually problematic areas, such as unreachable cracks and crevices, are occasionally treated with pyrethrin spray or diatomaceous earth.

Different approaches to implementing pest control procedures were developed based on differences among object types. Generally, stable objects which have been in uncertain environments, such as new acquisitions as well as objects returning from loan, and objects exhibiting signs of infestation, undergo preemptive pest control treatment by freezing for one week at -20ēC. Objects which are unstable or are made of materials that could be damaged by freezing, such as stretched skin, inlaid materials, or some painted surfaces, are treated in an anoxic environment using AgelessŽ oxygen scavengers in a sealed enclosure for the recommended minimum of 28 days. In addition to these two groups, we have categories of objects which are considered too culturally sensitive for either freezing or anoxic treatments. The determination of these objects is made by native representatives. The method of pest control for these objects is based on information and special requests from their respective native communities, and generally consists of isolation, thorough examination, vacuuming, and monitoring. The pest control needs of culturally sensitive objects are not so commonly recognized or followed in museum settings, but are nonetheless important in the conservation of Native American materials. The care regimen for these objects should promote physical conservation and also respond to culturally based concerns for preservation. As professional conservators we are trained to implement sound integrated pest management procedures, but for collections of Native American material it is also necessary and appropriate to broaden our perspectives to embrace caretaking in a way that is compatible with an object's use, maintenance, and spiritual life within its culture. The Native American objects that are now in museums were once integral parts of daily or ceremonial life. As such, they may have been visited and handled often, thus discouraging any damaging pest infestation. In museum settings, they no longer experience this level of contact; the very act of archiving these objects in undisturbed quiet places can actually leave them more vulnerable to unseen or unnoticed insect damage. While our standard pest control techniques will not harm the structure or component materials of collection objects, these techniques can impact inherent spiritual components. For culturally sensitive objects, the decision not to use standard museum pest control procedures respects culturally important concerns. For these objects the appropriate pest management care may be to follow the methods employed by their makers: inspection, monitoring and maintenance by a qualified caretaker.

When working with Native American collections, we need to provide professional, responsible care that does not contradict the spiritual and cultural needs of some objects. Incorporating traditional native care concerns into a pest management program doesn't necessarily compromise the standards to which museums usually adhere. Instead, this enhances and completes a pest management system by addressing both the physical and spiritual aspects of the collection objects. Both approaches are vital for truly comprehensive collection preservation.

Leslie Williamson
National Museum of the American Indian
Smithsonian Institution
3401 Bruckner Blvd.
Bronx, NY 10461


Nirmala Balram

Fiji's unique cultural and ethnographic heritage has long been of interest to many people. As a result, in 1904 a national museum, The Fiji Museum, was set up in the capital, Suva, and over the years a large variety of artifacts have been acquired, collected or received as donations from private collectors. The museum now houses a collection of over 60,000 artifacts, mostly from Fiji and other South Pacific Islands. Included in the collection are artifacts of historical, maritime and military importance. Of particular interest are the rare collections of early Christian objects, pre-Christian war clubs, masi (bark cloth), endemic fauna and the rudder of the HMS Bounty of Captain Bligh.

Since August 1996 the conservation department has had one conservator on staff. There had been no staff conservator for the previous ten years and only short periods of staffing earlier. Much needed assistance is provided by other collections department staff members. Current funds are inadequate for the care of collections and we are seeking additional outside funding from foreign embassies and commercial concerns. The staff conservator will receive three months of additional conservation training in Australia. Advice and help are also sought from conservators elsewhere.

The museum's laboratory is equipped with two large working tables, microscopes, heating equipment as well as glassware and required chemicals. Adjoining the laboratory is a holding area and storerooms where objects requiring treatment are kept.

A complete survey of the museum's ethnographic collection is now underway with the help of volunteers. A large part of the museum's collection is fabricated from tree trunks, branches, leaves or roots and the conservator has found degradation of these materials both in display and storage. Typical problems observed in the collections include fading from light exposure, distortion of objects, and infestations of insects. To make matters worse, storerooms were crowded and disorganised. These conditions were also exposing objects to continuous changes in temperature and humidity because of Fiji's tropical climate. Fortunately, there is a small air-conditioned storeroom where over the last few months many fragile and sensitive objects have been relocated. These are monitored weekly to ensure that environmental changes made are not harming the objects. In addition, all objects that were on the often damp floor have been placed on racks or tables and light levels have been reduced in all rooms. Movement of staff to and from the storerooms is also restricted now.

Currently, laboratory treatments include the following: washing and encapsulation of documents, stabilization of chipped and cracked wooden objects and cleaning and rehousing of many of the medal and weapons collections. Some masi (bark cloth) is also both dry and wet cleaned using deionised water and acid free blotting paper.

Pest control

In January of 1997 the Fiji Museum began to address its pest control issues. It is to be noted that in a small museum like the Fiji Museum that has a limited budget, only locally available resources can be used.

The first phase of the program was to observe the collections and evaluate what problems existed in the galleries and in storage. The collections themselves were constructed primarily of plant cellulose fibres. There were insect infestations in many of these artifacts. Dry wood borer beetles, for example, were well established in large wooden objects and had been active for over ten years. The storerooms were overcrowded with some objects stored on damp floors thus increasing chances of fungal outbreaks. Both major display galleries are exposed to external environmental conditions resulting in changes in relative humidity within the gallery and continual exposure to infesting insects and fungi, always problematic in this tropical climate. Wooden display units in the gallery were also prone to insect infestations. Some of the problems noted were resolved by rehousing objects as outlined above.

While the staff began investigating a safe and environmentally friendly means of pest control, the current outbreak needed to be controlled. The staff decided that fumigation was necessary and hired a pest control company, Rentokil, which was available locally. The program of treatment is outlined below.

1. Fumigation: Methyl bromide was chosen as the fumigant because it attacks infesting insects at all stages of their life cycle. Storerooms and large objects like canoes were fumigated with methyl bromide gas after carefully sealing them under a tarpaulin. Infested, smaller objects from display cases were also placed within the tarpaulin enclosures.

2. Residual chemical barrier treatment: A weak solution containing Deltamethrin (Deltamethrin pyrethroid) was applied with a brush to all infested artifacts including those that had been fumigated with methyl bromide because fumigation does not provide any residual protection.

3. Misting: The entire museum was misted with a 0.6% pyrethrum extract to remove any remaining adult flying insects.

4. Trapping: The entire complex was treated for rodents and ants with the application of Bromatrol based baits and boric acid insecticidal gel for ants.

The treatment program was conducted by Rentokil and required one week to complete. Following the treatment program, staff were allowed one week to reinstall the display cases. While pest control is an important part of the museum's agenda, it is hoped that the fumigation requirements can be reduced in the future.

Rentokil will follow up the initial treatment with monitoring and any necessary treatments as outlined below.

1. Six weekly visits by Rentokil are anticipated to monitor the presence of adult insects. The program is based on the life cycles of the insects concerned. Rentokil staff will also inspect all traps and baits, record insects collected, and replace traps as necessary. The data collected from the traps will be used to target problem areas of the museum for appropriate action by Rentokil.

2. Quarterly visits by Rentokil are also anticipated to mist galleries and the storage complex, as outlined above, for any remaining adult insects before they become established. The conservator and Rentokil staff will collect and identify which insects, and in what numbers, constitute a continuing threat to the collections. Using the collected data, a decision will be made as to the most effective course of continued pest control.

The staff is currently monitoring the effectiveness of the chemical treatments and will review the need for any additional treatments in the coming year. In addition, insect screens and climate control are being planned in order to help prevent access of pests into the museum. The staff conservator is now trying to develop an effective pest control program best suited to a museum on a limited budget using only locally available resources.

Nirmala Balram
Fiji Museum
Thurston Gardens
P.O. Box 2023
Suva, Fiji


Michael Trinkley

Integrated pest management, or IPM, has a nearly forty year history of successful use in agricultural settings, where it was first introduced. Its history in urban settings is somewhat more mixed, with the pest control industry itself still uncertain about whether to embrace this "least-toxic" approach. In the museum, library, and archival communities there is a fair amount of talk about IPM, but not a lot of activity, at least among the smaller institutions that typically still rely on what might be described as a "spray and pray" approach to pest control.

Before exploring why IPM isn't more commonly used at museums and how to make it more user friendly for the small institution, it's important to understand something of its philosophy and practices. There are four major components of a successful IPM program: assessment of acceptable pest population sizes, monitoring, identification and imple-mentation of control methods, and an evaluative process. The IPM program, unlike most commercial treatments, is not static, but should be designed for constant adjustment and refinement. The primary advantages are that stable, long-term control of most pest populations is possible and the use of toxic chemicals is minimized.

Often museum IPM practitioners argue that the threshold or action level for most pests is "one". That is, one cockroach or one dermestid or one carpet beetle is one individual too many. This is certainly a purist's approach, but is it practical, or even achievable? Probably not. It's important to realize that pests were here first and will probably survive us. If it's tough getting rid of pests in an apartment, then consider your collections. The museum setting, far too often, is a perfect setting for pests. Lights are reduced to avoid physical and UV damage to collections, access to storage areas is limited so there is little to disturb pests, housekeeping is often minimal, the collections provide a buffet for pests, and the environmental controls frequently are inadequate. Top all of this off with bad management decisions such as allowing food in the institution or allowing staff members to eat at their desks or adding a restaurant to the museum's public wing and you have a ready-made problem.

Of course, there are some pests which must be totally eliminated from the museum, library, or archive setting because of public health concerns. Clearly, rats and mice are among the most serious, although cockroaches are probably of equal concern. Nevertheless, institutions must seriously consider the level of pest management they hope to accomplish and set their threshold levels accordingly. Just as importantly, these levels should be periodically evaluated and re-assessed. By extension, this means that it is very important to periodically review and evaluate your collections to determine the amount of pest activity present.

Fundamental to the success of IPM is the ability of its practitioners to out think the pests, to be smarter than the insects and rodents they are seeking to manage (or control). Monitoring for pests is the key. Far too many institutions view monitoring as either a needless waste of time or requiring nothing more than placing a few sticky traps and examining them when things are slow. Monitoring and trapping are a delicate blend of science and art that few in the pest control industry have mastered. First, it's essential that you understand the life cycle of the pests you are monitoring. This will help you better evaluate where to place traps. Taking cockroaches as an example, if you are concerned about outdoor-living species, such as the American or the Smokybrown, then traps should probably be near points of entry, and in attics or crawlspaces. Oriental cockroaches might require traps in basement areas and around steam pipes, rather than on upper floors and dry areas. The presence of German cockroaches would suggest the need to place traps in areas providing moisture and food, such as in cabinets in kitchen areas.

Continuing to focus on cockroaches for our example, we should be familiar with their tendency to travel along floor/wall intersections. In fact, some research reveals that moving a trap as little as 1/2 an inch from the wall will reduce the number trapped by 50%. Shifting the trap 2 inches from the wall reduces the catch to only 10% of the number caught as compared to traps correctly placed at the wall/floor interface. While many sticky traps have a typical tent shape (allowing contact with only one surface), those which have a sticky surface against two surfaces greatly increase the chances of capture and more successful monitoring. A good example is the Catchmaster Super Glue BoardŽ. But even the tent style Insect Trap and Monitor by Catchmaster can be made better by "crushing" the trap to create two very small raceways. This "thigmotrophic" alteration helps to satisfy the roach's urge to squeeze into tight places.

Understanding the life cycle and habits of pests are important to proper placement of traps. Care should be taken not to limit the success of your monitoring program by using too few traps. Essentially, you can't have too many traps, but you must remember where they are and keep track of them for periodic checks and replacement. In addition, traps should never be placed in wet areas (because they are usually ruined by moisture) or in dusty environments (because the dust collecting on the sticky surface reduces their effectiveness). Also avoid placing traps in open floor areas because these areas are only rarely used by pests. Don't be persuaded to use more costly scented traps for insect monitoring, because most pests aren't attracted to the peanut butter, chocolate, or cherry scents used. And finally, remember where traps are placed and check them weekly during the initial stages of your monitoring program.

Just as placement is essential, so too is the ability to "read" the trap. While it's certainly important to be able to correctly identify the pest you've caught, it is also important to know the life stage. For example, again using our cockroach example, if you catch primarily nymphs or only adults, then you probably have a new infestation. If all life stages are captured in varying numbers, you probably have a well-established population. And for every one captured, there are likely between 200 and 280 in hiding. For every trap, take careful note of where the insects are on the trap and what direction they were heading when captured. If all of the insects are on one side or are headed in the same direction, this offers you an essential clue on where the infestation is coming from. As the number of traps being used is increased, you are better able to narrow the site of the harborage. Here again it's useful to understand the habits of the pest. For example, German cockroaches rarely venture beyond 10 to 12 feet of their harborage area, unless there is severe stress for food and water.

Methods for controlling pest infestations should begin with building modifications. Control methods have two fundamental goals: eliminating access and denying food sources and moisture. The building envelope, recognized as the first line of defense against environmental fluctuations, is also the first line of defense against pests. Outside the building, improving grounds management (eliminating organic mulch next to buildings and pruning overhanging limbs and vegetation) and changing lighting (replacing ordinary outside lights with sodium vapor lights) can make life in and around a museum less attractive to pests. Mechanical modifi-cations include weatherproofing doors and windows, screening air vents, and sealing wall cracks (which will eliminate access points and pay an additional dividend of helping to minimize interior temperature and humidity fluctuations). Inside the building, interventions include such concerns as thorough cleaning, eliminating food and drink in appropriate areas, and reducing temperature and lowering relative humidity (low temperatures and low relative humidities reduce insect populations).

Eventually, however, it is possible that chemical treatments will be necessary. While an institution may develop and implement an IPM program internally, most rely on outside pest control companies for chemical applications. And this is often one of the weakest links in the IPM chain. Here in the United States it is important to understand the laws regulating pesticide applications. For example, the principal law, the Federal Insecticide, Fungicide, and Rodenticide Act or FIFRA requires that restricted-use pesticides be applied under the control or oversight of a licensed applicator. This doesn't mean that the individual walking through your facility is licensed, only that he or she is working under the (possibly remote) supervision of an individual holding a license.

Even chemical treatments are appropriate within the IPM context, if several critical issues are recognized and addressed. First and most fundamentally, you must know the pest or pests involved and their life stage. Treatments should never be allowed for the nebulous reason that "bugs have been reported." IPM requires entomological solutions and these require that you know the pest. For example, if German cockroaches are the problem, it's important to understand that a quick and effective knockdown of about 90+ % with the first application is essential, if control (or management) is to be achieved. Beyond this, FIFRA requires that the pest control applicator identify the target pest and ensure that the chosen pesticide is labeled for that pest. You must also know where the pests are living or finding harborage in order to treat the source, not the general area. Research reveals that for many pesticides, prolonged contact is essential to ensure a kill. Such prolonged contact is possible only when pesticides are applied to harborages, not when they are generally broadcast.

Institutions should be aware of the tremendous increase in new pesticides and pesticide formulations. An important consideration is the formulation wettable powder or emulsifiable concentrate, for example. An emulsifiable concentrate (EC) does not necessarily provide long-term residual activity on nonporous or semi-porous surfaces that are found in most collection storage areas such as metal, ceramic tile, and painted surfaces. Wettable powders are frequently avoided because they leave a white film behind, yet this formulation is often far more effective, especially if correctly applied to where pests are hiding. Dusts are perhaps even better, because they allow application directly into voids and other harborage areas. Micro encapsulated insecticides offer the potential for very long residual control. It may be that changing from a liquid pesticide to a gel or dry pellet insecticide mixed with some food material and a feeding stimulate (normally called a bait) may be a better choice. It may also be appropriate to use an insect growth regulator, where available, for pest control.

Pesticides must be carefully selected and applied. A pest control operator that "routinely" uses one or two pesticides for all his clients is probably not going to be able to offer your institution the service you need. Look elsewhere for a more sensitive company willing to work with your IPM program. Likewise, look for a new pest control firm if yours is still adamant that "preventative spraying" is essential. This routine use of pesticides has resulted in a number of cockroach species that are resistant to a wide range of the new pyrethroids. Chemicals should be used only when necessary, not as a technique to prove the pest control company is earning their monthly fee.

Finally, part of any IPM program must be documentation. Just as the traps and their catches must be documented, so too must all pesticide treatments be recorded. Far too many institutions, when questioned about the pesticides being used in their facilities, have absolutely no idea what is being used, where it has been applied, or how often. Without this knowledge they have no way of knowing if the treatments are appropriate or effective. Minimally you should insist on obtaining a copy of the label of the pesticide from your pest control operator. Target species must be listed on the label of any pesticide. The rate of application should also be documented so that you know how much pesticide, in what concentration, was applied. Pesticide labels allow you to verify the application usage in your facility to the rate and concentration recommendations on the label instructions. Finally, you should document where the pesticide was applied. Noting that it was "sprayed as necessary" or "in exhibit halls" is totally inadequate. Specific information is obviously helpful in helping to track the affect of the treatment on the pest population and may also be very important in tracking exposure of collections to pesticides. A final requirement prior to the use of a chemical pesticide is that the pest control operator provide you with a copy of the material safety data sheet (MSDS) for the pesticide. This provides information concerning exposure limits, as well as the health consequences of exposure.

This discussion has probably made it clear that IPM requires extensive training and staff commitment. It hinges on the use of an integrated approach - simply throwing out a few traps and then spraying is not IPM. The tremendous amount of up-front time discourages many smaller institutions from ever attempting to implement IPM in their institutions. Smaller institutions, however, can implement IPM on a gradual basis. While such interim programs should not be called integrated pest management, they can help establish a bridge to an IPM program and they can make a real difference in staff, patron, and collection health and well-being. This interim approach should focus on critical issues such as identifying the pest, finding the source, and approaching treatment as broadly as possible. Ideally treatment will include modifications in the physical and mechanical surroundings, followed by the use of chemicals if needed. But even if the institution more carefully reviews the formulation and types of pesticides being used, and insists on having label and MSDS information, positive steps will have been implemented. Consequently, IPM isn't just for the "big guys," although smaller institutions may find it necessary to "back into" IPM using what some have called "situational pest management."

For More Information

Anonymous, Pest Control in the School Environment: Adopting Integrated Pest Management, Washington, D.C.: U.S. Environmental Protection Agency, Office of Pesticide Programs, 1993.

Provides an overview of how an IPM program may be developed for a local school setting. This offers a range of ideas and actions that are equally appropriate for the museum, library, or archives setting.

Anonymous, Integrated Pest Management Records, Management Report ESPC 025411, Dunn Loring, Virginia: National Pest Control Association, 1996.

Presents forms that commercial pest control firms can use to provide a record of service to a client's facilities, document trapping and monitoring, and identify occupant reported problems. While there is plenty of room for improvement, it demonstrates that your current firm has no basis for complaining that they don't understand what you want.

Hedges, Stoy, "Entomological Solutions," in Pest Control Technology, July (1995): 60-61, 64, 66, 68, 117.

Provides a quick overview of interim approaches, explaining how situational pest management can help control pest populations.

Olkowski, William, Helga Olkowski, and Sheila Daar, "What is Integrated Pest Management?" in The IPM Practitioner, 13, no. 11-12, (1991): 1-8.

Although a little dated now, this provides a detailed examination of how an IPM program may be integrated into urban pest control and still serves as one of the primary sources for newcomers in the field.

Robinson, William H. and Jeffrey Tucker, "IPM: A House of Cards?" in Pest Control Technology, June (1995): 34-35, 39, 42.

This is an interesting exchange in the pest control field pointing out just how many pest control operators are fundamentally opposed to IPM programs. The article illustrates why institutions must be strong advocates in their own behalf when dealing with commercial pest control firms.

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

Ruth E. Norton

Editors’ Note: A more detailed version of this article can be found in 11th Triennial Meeting Edinburgh, Scotland, of the International Council of Museums Committee for Conservation, 61-67. London: James & James, Ltd., 1996.


In late March 1995, a severe infestation of T. bisselliella was found in Anthropology Storeroom 3 at the Field Museum of Natural History in Chicago. The Field Museum did not have a designated pest management officer; therefore, the Conservation Department, within the Department of Anthropology, was immediately responsible. An object with concentrated pest activity was located. It and adjacent objects were immediately bagged and frozen. Although a number of moths were sighted throughout Room 3, it was not known how widespread the infestation was. Other storerooms were also considered to be at risk because over the past several months objects from the infested room had been moved into three adjacent storerooms. A large number of objects was involved: 4700 in the infested room and 38,000 in the adjacent rooms. All were on open shelving. The immediate and potential danger to the Anthropology collection was high.

Initial inquiry1,2 confirmed that the first priorities would be isolating the infestation and slowing down the moth activity until a method of management could be established. Luckily, Room 3 was on an individually controlled thermostat, so the temperature could be lowered to 16C to reduce activity of all stages of the moth. The room was sealed off with plastic sheeting and tape over doors and vents. Access to Room 3 and adjacent storerooms was restricted.

Pest control companies and advisers were invited to submit advice and bids to set up a monitoring program to determine the extent of the infestation in Anthropology and to bring the infestation in Room 3 under control. The size of the infested area, the number and nature of the objects, the location and construction of the room, and public and staff safety issues placed constraints on means of combating the problem. The storeroom was in an interior space and could not be sealed off from staff and public areas, eliminating the use of toxic gas. Water based pyrethrin spray could have been safe for staff and public, but could not be used on objects. The room was constructed of masonry and concrete which had proved in the past to be too permeable to utilize gaseous N2 or CO2 for oxygen deprivation.

Monitoring Anthropology storerooms, workrooms, offices and labs to determine the extent of the infestation appeared to be fairly straightforward. However, several very different approaches were proposed for eradicating the current infestation in Room 3. Evaluating these took consi- derable time and discussion with entomologists. The approach finally adopted3 was one which was based directly on the known behavior of the insect, necessitated only minimal movement of objects, and could be implemented solely by museum staff.

Life cycle and habits of T. bisselliella

Particular aspects of the life cycle and habits of T. bisselliella were important to the final program implemented.4,5,6 The larval stage of the insect is the only one which causes loss in objects. Because of their preference for dark, hidden areas, and the complex structure of many of the objects they feed on, their presence may be undetected for years, and a population may reach considerable size. The larvae can lie dormant in their feeding webs, and the eggs and pupae remain securely attached to objects; all can be easily transported on material to new sites. As the larva incorporates surrounding object fragments into its pupal cocoon, the pupa becomes very well camouflaged. While the eggs are usually deposited on a food source, the pupae can be found on any material, including paper, plastic and metal.

If a population is detected soon after emergence, the actual area of concern is limited. T. bisselliella has a tendency to aggregate and remain for generations in a dense core, not moving until food is depleted, at which time the population emerges and swarms. Although both male and female adults can fly, the females are heavily laden with eggs and do not usually fly or walk far. They are more likely to tumble to a lower shelf. As the females and larvae both do not travel far, the eggs and pupae from which the next generation emerges are found within 2-3 m of the infestation core. This considerably reduces the area and number of objects requiring treatment. Although the male adults fly readily, they are not inherently a problem. In fact, their movement provides an important clue that a population is emerging, and their concentration can be used to pinpoint the infestation core.

The rate of development varies greatly with environmental conditions. Warm, humid environments encourage growth (22ēC and 75% RH is perfect). The lower the humidity and temperature, the slower the activity. There is seasonal variation in growth spurts as well. In temperate climates, early spring and late autumn seem to be times when a population emergence is most likely to occur, and when inspection may be required more frequently.

Procedure implemented to determine extent of infestation

The procedure used to determine the extent of the infestation consisted of establishing and maintaining a long term monitoring program for T. bisselliella. Suspended sticky traps containing its pheromone lure were used. The lure is the chemical equivalent of the female sex hormone to which adult males are attracted. Each lure is effective over a 6 m radius. After 3 months its effectiveness decreases, and a new lure must be added to the trap. The pheromone is prone to oxidation, so unopened lures have a refrigeration shelf life of one year.7 Traps and lures were placed in all Anthropology storerooms, offices, workrooms and labs. Those adjacent to the infestation were checked every week for the first month and once a month thereafter. To date, no further outbreaks have occurred in Anthropology (two years later).

Procedures followed for identifying, controlling, and cleaning up after a T. bisselliela infestation in Storeroom 3

  1. Locate infestation core by visual inspection or by using traps to triangulate greatest population density.
  2. Identify species of insect (in this case T. bisselliela), and its life cycle and habits. (Accurate species identification is essential because eradication procedures are based on it. Procedures may vary for different insects.)
  3. Lower temperature of storeroom if possible to 15-16ēC to slow down moth activity during isolation and cleanup.
  4. Bag, seal and remove all infested objects and all adjacent objects surrounding the core. Bagging keeps all stages of the insect from being spread while moving objects, and is required for freezing. The size of the area to be cleared may vary depending on insect and extent of human activity. For T. bisselliella in an area with little human activity, we were primarily concerned with the area within a 2-3 m radius of the core.
  5. Freeze all bagged material. We used -20ēC for 7 days.8,9
  6. Dispose of or freeze all shelving and support padding, plastic, paper and boxes. Eggs and pupae can be firmly attached to them. Don't just carry them out of the storerooms. Bag or box them first so eggs, larvae, pupae and adults are not accidently dropped and distributed.
  7. Thoroughly vacuum the cleared area including tops, bottoms, and sides of all surfaces, cracks, and crevices. A vacuum cleaner that is dedicated to pest cleanup is best, but any vacuum cleaner will do as long as it uses disposable vacuum bags. After vacuuming the area, seal the vacuum bag in a plastic bag and dispose of it immediately in a dumpster outside the museum building. Remember, you've vacuumed up eggs, larvae, pupae and adults into a warm dark vacuum bag, perfect for hatching and growth. Freeze the vacuum cleaner to kill any insect stages caught in hoses and nozzles.
  8. Thoroughly wipe and mop down the cleared area with warm water and disinfectant soap or with alcohol. Rinse if necessary. Again, you are trying to get rid of any eggs, larvae, or pupae which have settled or fallen on surfaces and in cracks.
  9. A pyrethrin spray can be applied to cracks and crevasses to kill off anything you haven't been able to remove. Pyrethrins are contact insecticides with little or no residual power; their application is not likely to do anything that you haven't already done with vacuuming and wiping. But if there are hard to reach crevasses, it might help. (We found the pyrethrin spray more useful in reducing activity in initial cleanup of outbreaks in non-collection areas of the museum).
  10. After freezing, remove all insect residue from objects before replacing them in storage. This makes future inspection possible as you will know that any insect debris found is a new infestation and not residue from a previous problem. This was by far the most time consuming part of the cleanup, but one which should not be overlooked.

In our case, we freshly bagged and sealed all objects before returning them to storage. This was partially because of dust problems in open storage, and partially so that these objects would not require retreatment should the infestation prove to have spread beyond the treated area. We also marked all the bagged objects with the procedure and date. Although this information was in the object files, inspections are easier if the information is in storage.

Occurrence and clean up of T. bisselliella in non-collection areas of the museum

Infestations in non-collection areas of the museum maintain a resident population for reinfesting collection areas. Factors promoting infestations of T. bisselliella were found to be storage of soiled protein materials and poor housekeeping. Good housekeeping practices such as regular and thorough cleaning of all areas of the museum, and regular inspection and inventory of stored and incoming materials could considerably reduce the risk of infestations.

The procedures for containing and cleaning up non-collection infestations were similar to those in collections, but because one is often dealing with disposable material, the resource of staff time is considerably reduced. Refer to the previous section for cleanup procedures.

Monitoring and pest management, after controlling the infestation

The results of the monitoring indicated that the infestation had not spread beyond the core, and that removal of the core objects and cleanup of the immediate area effectively removed the infestation.

Each pheromone trap was inspected once a month. During spring and autumn when outbreaks are more likely to occur, traps were inspected more frequently. Species and number of insects found in the traps were recorded on a database.

After nine months of monitoring, no significant number of insects were found in the infested and adjacent storerooms. Out of the twenty traps used to monitor the area, only four moths were found, which occurred in different locations and were probably strays. Also, moths were consistently found in several curatorial offices every month. These were probably inadvertently brought in by staff on clothing. It was not a cause of major concern, but pointed to the need for more active awareness of pests by all staff and the need to continually monitor for any sudden increase in population.

The above outlines the aspects of the monitoring program directly related to the infestation of T. bisselliella. The monitoring program actually implemented was much broader and included window and floor traps and lures for dermestids and cigarette beetles. It was based on information gained during a detailed site inspection by an entomologist with pest management experience (Dave Mueller, Insects Limited, Inc.). The site inspection was extremely beneficial and is recommended to any institution establishing a pest monitoring program.


A detailed and practical understanding of the life cycle and habits of specific pests are critical to effective pest management and infestation control. Monitoring and cleanup procedures are based on this information.

Monitoring and inspection indicate that the procedures used to contain and clean up the infestation of T. bisselliella (freezing objects, vacuuming and washing storage facilities within 3 m of the infestation core, and removing insect residue from objects before returning them to storage) have been effective in Storeroom 3. The resources required to contain and clean up the T. bisselliella infestation in the Anthropology storeroom (16 m2 holding 400 objects) consisted of 515 person hours, $300 for materials, and 18 weeks of freezer space. Cleanup of non-collection area infestations required only 35 person hours on average, as infested material was often disposable. The costs of containing and cleaning up the infestations in Anthropology storage and in non-collection areas of the museum was $8,585 and $1,630, respectively.

Overall, the total monitoring program covered 7830 m2 of storage space ( 9 object storerooms housing a collection of 1,000,000 objects) and work space (20 Anthropology offices, labs and workrooms). About 100 floor, window and hanging sticky traps and 70 lures were initially used. Sticky traps required replacing about once a year and new lures were added four times per year. The annual cost of the traps and lures for the monitoring program was about $1300. Total staff time for inspecting, recording data and adding lures was 112 person hours. Setting out traps and setting up the data base required an initial investment of 25 person hours. Including salaries, the initial annual cost of monitoring all of Anthropology was $1,680.


1. Mueller, D., Personal communication, 1995. Insects Limited Inc., 10540 Jessup Blvd., Indianapolis, Indiana 46280-1451, USA.
2. Pinniger, D., Insect Pests in Museums, London: Archetype 1994.
3. Procedures were based in large part on advice by D. Mueller, Personal communication.
4. Mallis, A., "Clothes Moths," in Handbook of Pest Control, revised by T. Parker, 350-357. Cleveland: Franzak and Foster, 1990.
5. Mueller, Personal communication.
6. Zycherman, L.A., and J.R. Schrock, eds. A Guide to Museum Pest Control, Washington, D.C.: Foundation of the American Institute for Conservation and the Association of Systematics Collections, 1988.
7. Mueller, Personal communication.
8. Strang, T., "A Review of Published Temperatures for the Control of Insect Pests in Museums," in Collection Forum, vol. 8, no. 2 (1992): 41-67.
9. Florian, M. L., "The Effect on Artifact Materials of the Fumigant Ethylene Oxide and Freezing Used in Insect Control," in Eighth Triennial Meeting, Sydney, Australia, of the International Council of Museums Committee for Conservation, 199-208. Marina del Rey: Getty Conservation Institute, 1987.

Materials and suppliers

NoSurvivorŽ Diamond trap (hanging sticky trap)
Webbing clothes moth bullet lure
Cigarette beetle bullet lure
Trogoderma spp. bullet lure
Produced and supplied by Insects Limited Inc., 10540 Jessup Blvd., Indianapolis, Indiana 46280-1451, USA

Mr. StickyŽ (floor and window sticky trap)
Manufactured by Mr. Sticky South, 819 Main St., Greenville, Mississippi 38701, USA 1-601-335-6390

PTŽ 565 Pyrethrin Insect Fogger (0.5% pyrethrins, 1% piperonyl butoxide, 1% n-octyl bicycloheptene dicarboximide, 97.5% inert ingredients)
Manufactured by Whitmire Research Laboratories Inc., 3568 Tree Court Industrial Blvd., St. Louis, Missouri 63122, USA 1-800-325-3668

Ruth E. Norton
Heritage Conservation
P.O. Box 363
Cuttingsville, VT 05738

Jeremy F. Jacobs

One of the more insidious pests encountered in museums today is the odd beetle, Thylodrias contractus. This tiny insect (family Dermestidae) is rapidly finding its way into many of our major natural history museums. The prevalence of these insects in museums may be related to the worldwide shipment between museums of specimens possibly harboring the insect or, perhaps they may have always been present but are now more readily observed due to increased Integrated Pest Management (IPM) monitoring and restricted pesticide use.

The odd beetle, Thylodrias contractus, was named by Motschulsky in 1839. It wasn't until the turn of the century that this rare and elusive insect was placed in the Family Dermestidae by Slosson1. Mertens2 thought that the original distribution of Thylodrias was probably the holarctic regions of Asia. Unfortunately, there are no historical records containing actual sitings of the odd beetle in the natural world, so it may be impossible to ever determine the original natural range of the species. Most recorded sitings today are in museums and in other man-made structures3.

The name "odd beetle" is aptly given. As an adult, this species is sexually dimorphic. The adult males are winged, elongate, and have a maximum size of about 3mm in length. In contrast, the adult females are wingless and larviform and can reach 5mm in length. The females closely resemble the larvae although they have fewer body setae and a more robust thorax.

Life history data on this species is scant. Mertens2 describes the life history of Thylodrias in greater detail than any other researcher. Eggs are laid by the female over a period of 7 to 11 days. Incubation then takes about a month, at which point the eggs hatch into a larval stage. The larval stage of Thylodrias lasts about 275 days if well fed but can extend up to 5 years under certain circumstances (e.g., lack of food source). The larvae may shed from 5 to 12 times throughout development and go through 5 to 8 instars. The pupal period lasts only about 10 days and the adult insects live about 30 days.

Odd beetles have been found in several collections in the National Museum of Natural History, Smithsonian Institution. In the Division of Mammals they persist as an ongoing and active pest problem. They appear to inhabit the dark spaces found under specimen storage cases where they probably feed on dead insects and other organic material. When active inside specimen storage cases, they cause noticeable damage to specimens, severing hairs on fur specimens, both in the mammal collections and in the anthropological collections. They have also been observed burrowing through bone specimens where they presumably feed off dried tissue or bone marrow. In addition, they actively attack study skins and bird nest specimens in the bird collections.

To combat these problems with the odd beetle, the Division of Mammals has implemented a four-part IPM program. The first part of the program includes monitoring and assessment of the odd beetle population. Sticky traps are placed around the collection area on floors, in specimen storage cases, and on top of storage cases. After several monitoring cycles (lasting about 2 months each) the following observations were made: 1) odd beetles were never found on top of storage cases but were very abundant on the floor around the specimen storage cases, 2) traps placed inside of storage cases were unsuccessful in catching this insect even when the cases were known to be infested, and 3) throughout 5 years of trapping in our collections, a life history pattern of the beetle became evident. Adult odd beetles were found in the greatest numbers in the month of May and the highest density of larvae occurred in July4. This supports the life history data of Mertens2 which reports that the adults are short-lived and that the eggs require about 30 days to hatch.

The second and third phases of our IPM program include housekeeping and visual inspection. All of the floors around specimen storage cases are vacuumed every two months because the floors were the site of the greatest number of odd beetles. In addition, because the sticky traps were unsuccessful in catching odd beetles inside of the specimen cases, a program of visual inspection has been instituted. To aid in this endeavor, white, unbuffered, pH neutral blotter paper is placed under all of the specimens inside storage units in collections storage areas where the largest numbers of odd beetles had been trapped. The white blotter paper creates a background that allows inspectors to easily observe frass, shed skins, live insects, and any specimen damage.

The final phase of the IPM program involves the use of pest control procedures. When an active infestation is found, the entire contents of the specimen storage case are removed and exposed to a 60% atmosphere of carbon dioxide for about 20 days in an enclosed chamber. In our experience, using this technique at a temperature above 75ēF appears to be effective in killing all stages of the odd beetle. When it is not possible to use the carbon dioxide chamber to eradicate an infestation, either because the chamber is already in use or the quantity of specimens is too large for the chamber, PDB (Paradichlorobenzene) is placed inside of the specimen storage cases and sealed for at least eight weeks. This technique also appears to be fully successful in killing all stages of the odd beetle.

With the implementation of our IPM program, the Division of Mammals has been able to reduce the incidence of odd beetle infestations in the collection over the past four years. As our knowledge base grows, other techniques will be investigated and tried in an effort to further reduce the threat that this pest poses to the collection.


1. Slosson, A.T., "A Coleopterus Conundrum," in Canadian Entomology, 35, (1903): 183-187.
2. Mertens, J.W., "Life History and Morphology of the Odd Beetle, Thylodrias contractus," in Annals of the Entomological Society of America, 74(6), (1981): 576-581.
3. Alpert, G.D., "The Role of the Odd Beetle, Thylodrias contractus, in the Biodeterioration of Museum Objects," in Biodeterioration Research, edited by G.C. Llewellyn and C.E. O'Rear, 309-315. New York: Plenum Press, 1987.
4. Jacobs, J.F., "Pest Monitoring Case Study," in Storage of Natural History Collections: A Preventive Conservation Approach, 221-231. Pittsburgh: Society for the Preservation of Natural History Collections, Pittsburg, 1995.

Jeremy F. Jacobs
Division of Mammals
National Museum of Natural History
Smithsonian Institution
Washington, D.C. 20560

Stefan Michalski

Editors’ Note: This text was first distributed through the Conservation Distribution List on the Internet on October 7, 1996. It is presented here with minor changes for clarification with the author's permission.

We have a largish choir book (late 18th century), manuscript on parchment, bound in wood boards and have discovered signs of recent insect activity. We have a blast freezer and for many materials would deal with this by rapid freezing to about -50 degrees Fahrenheit, approximately -43 degrees Celsius, but faced with this object, my confidence flags and would be most grateful for advice, anecdotal experience, cautions, exclamations of horror or delight, or failing that, pointers to literature.
- Walter Henry

It seems inevitable that Canadians are familiar with freezing our things. I was asked about freezing even before pest control. Since my CCI colleague, Tom Strang1, has written extensively on low (and high) temperature pest control, we have, of course, double-checked our knowledge in this area. I would like to briefly summarize the M. L. Florian article in Leather Conservation News2 for those unable to find it easily, and then build on it.

This is a rather long response, so the executive summary is: freeze most artifacts with confidence, especially those typically at risk from pests but, coatings prone to cracklure, on wood, may crackle a little bit more by -50ēC. Appropriate bagging techniques must be used to avoid either condensation or low humidities during cooling and retrieval. Such bagging will be presumed throughout the rest of this response, and its reasons and methods will not be discussed in further detail. For more information regarding bagging and retrieval procedures, refer to Michalski, S. "Retrieval from Cold Storage" EDR Report 1612, Canadian Conservation Institute, 1987.

As Florian points out, the most compelling evidence that freezing will not harm most artifacts is anecdotal, and massive. (Bad anecdotal evidence may be bad, but good anecdotal evidence is still the best.) No craft wisdom or modern observation that we know mentions problems due solely to low temperature, not in the artifacts of Europeans or those of our First Nations, many of which have seen -30ēC routinely, -50ēC in the high north. Michael Gates (curator, Parks Canada, Dawson City, Yukon) has monitored his own humidistatically controlled storage (which is usually ambient temperature or a little above) for two decades and reports no mysterious effects.

As to scientific explanations, Florian provides some of the references for moisture content work in collagen and wood, but I think it fair to say that the following consensus has emerged in several bodies of literature, both theoretical and applied, for the behavior of water in porous adsorptive materials below 0ēC.

At waterlogged conditions, the liquid water simply freezes, i.e., turns to ice. Some water may migrate from high solute regions before doing so, or from smaller pores (see below). In the process, macro- and micro-structure may get damaged. This is the issue for foods, floods, wet-site archaeology, and mortality, but it is not the issue here.

At 75-100% RH, something similar to freezing can still occur because moisture is held in micro pores as liquid (sort of). The freezing point is lower in smaller pores than larger pores (the "Kelvin" equation based on pore diameter gives the depression). This gives rise to an "icing-out" phenomenon known for both organic and inorganic pore distributions: the water in larger pores will freeze first, and if they aren't full, they suck up water from the smaller pores. Thus, Litvan3 proposes that the difference in frost resistance of things like bricks or stone depends on a sufficient volume in the large pores to accommodate all the small pore water without filling. But that isn't the issue here.

Below about 75% RH (and aside from systems with lots of solutes) the popular but simplistic phenomenological model of water menisci in little pores gets into trouble since the adsorption models yield water only 1 or 2 molecules thick, hardly enough to call a meniscus (much of the water at these levels is ABsorbed within the various polymer constituents). This is the area with the least data, but I think this is so because experience has never shown it to be relevant to material durability. A very recent study by Lars Bjordal, paper conservator at Uppsala Univ. Library (E-mail: lars.bjordal@ub.uu.se), of repeated freezing on paper strength showed no significant effects. The only two papers I ever found on the state of water at these conditions were both NMR (nuclear magnetic resonance) studies. This technique is very sensitive to any change in the molecular neighborhood of water molecules. In wood, A.J. Nanassy4 concludes that "starting at about 0ēC water molecules are approaching a rigid position. This occurs below about -30ēC." This study went to -60ēC and found nothing sudden. The Russians, Flyate and Grunin5, studied low temperature effects on paper pulps because they knew freezing of high water content pulps reduced sheet strength. They looked at NMR signals before, during, and after -21ēC, and found definite changes if equilibrium moisture content (EMC) was 16% or above, but the 3.4% and 9.2% EMC samples were unchanged. Thus freezing, i.e., absorbed moisture doing some kind of phase change (like ice) is not the issue.

What about the endless discussion over the low temperature correction to EMC at fixed RH, a perennial art in transit topic? Stolow6 showed the wood and cotton data to our field 30 years ago. To keep EMC constant, take the ratio of his beta/alpha coefficients, for wood and cotton: 3% RH drop for each 10ēC drop. He noted that since silica gel has negligible correction, it held RH well. Toishi pointed out we should stabilize an artifact's EMC, not RH, so buffer like with like. Thomson found where the opposing effects of dead air in the enclosure and the artifact meant the two canceled out. I7 pointed out oil paint appears to have no temperature correction, so you can't keep both wood and paint at constant EMC or RH, pick one only. M. McCormick-Goodhart8 has a nice variation on this recently: given gelatin’s tendency to get soft and sticky at 80% RH at room temperature, and its large temperature correction, then if 60% RH is a safe upper limit at room temperature, then this becomes 40% RH in cold storage. None of this is the issue here either. Why this irritating preamble? Because these peripheral issues always rear their ugly heads when "freezing", or more correctly, low temperature, is discussed.

I think the issues are shrinkage and embrittlement. If this seems little progress in twenty years, let me expand. Conclusions first: Tom Strang and I are convinced that shrinkage and embrittlement do NOT cause significant deterioration to the great bulk of historic artifacts that need pest control, and any risk that may occur is small compared to even a 1% probability of pest infestation if the artifact is not cooled. (All full citations for most of the following facts are in my article in Art in Transit cited above). First, assume cooling in a closed bag, so we can ignore the RH/temperature factor, and just look at fixed EMC cooling. Shrinkage due to temperature in amorphous polymer media below the glass transition temperature (varnish, oils, glue, gums) is roughly uniform in the glassy region: about 0.7% for a 70ēC drop, sometimes less. Pigmented media will experience about half this: 0.4% for a 70ēC drop. As given in the Wood Handbook, USDA, Washington DC, 1987, and as discussed by M. Richards in his chapter in the Art in Transit book cited above (pp. 279-297), wood has shrinkage across the grain of about 0.25% for a 70ēC drop, along the grain of only 0.03% (due to its crystalline cellulose). Estimate shrinkage of paper and parchment as slightly less than that of cross-grain wood: 0.2% for a 70ēC drop. Given the structure of old books and most other artifacts, a few significant differentials arise: paint and varnish on stretched canvas, varnish versus wood along the grain, paint versus wood along the grain, and cross-grain wood. These all give upwards of the full response of medium versus immovable boundary, i.e., 0.7% for a 70ēC drop. To place this in perspective, it is the same strain that is caused in these same systems by a drop from 60% RH to about 30% RH. These worst differentials are just at the verge of fracture strains in brittle glassy amorphous polymers. Mecklenburg and Tumosa (Conservation Analytical Laboratory, USA) provide more numerical detail on this cold temperature explanation for cross-grain cracks in coatings at the Painted Wood Conference in Williamsburg, 19949. M. Richards (National Gallery of Art, USA) also gave his data and this model at the recent Getty Panel Painting symposium. Patrick Albert (Centre de Conservation de Quebec) is planning some experimental study of the low temperature effect on wood varnish cracklure. For other material combinations, the shrinkage differentials are much less risky: paint on parchment, ink on parchment will experience less than 0.2% for a 70ēC drop. Even wood across the grain versus brass battens seems OK: 0.25% - 0.14% = 0.11%. Luckily, most artifacts in dire need of pest control experience negligible differentials: textiles, fur, feathers, skins, single pieces of wood, all possibly with lean paints (no medium, no problem).

So, getting back to Mr. Henry's book: If the wood boards are not battened by cross-grain wood strips or firmly attached metal, they are not at risk, as long as the bagged book is wrapped a couple of times with a wool blanket or the equivalent to reduce temperature gradients on the boards. (Bag and cuddle! But not so much the bugs can adapt!) If the boards are heavily varnished, I have to say there is a small but real risk cracklure will increase. There is only a tiny risk that any illumination or ink on parchment or paper will crackle more. (They will be at much higher risk in anoxia treatment if the humidification fails.) If you want to monitor a complex artifact such as this before and after cooling, I would certainly suggest you focus on existing cracklure and cross-grain wood joints for careful documentation, e.g., macrophotography. If anyone collects such data, please share the information. I would be happy to pool and share the info. (I research this stuff, and I'm coordinator of the ICOM-CC Preventive Conservation Working Group. If it's embarrassing, send it to me anonymously!)


  1. Strang, T., "A Review of Published Temperatures for the Control of Pest Insects in Museums," in Collection Forum, vol. 8, no.2 (1992): 41-67.
  2. Florian, M.L., "The Freezing Process - Effects on Insects and Artifact Materials," in Leather Conservation News, vol. 3, no. 1, (Fall 1986):1-13, 17.
  3. Litvan, G.G., "Freeze-thaw Durability of Porous Building Materials," in Durability of Building Materials and Components, ASTM STP 691, eds. J. Sereda and G. Litvan, American Society for Testing and Materials, (1980): 455-463.
  4. Nanassy, A. J., "Temperature Dependence of NMR Measurement on Moisture in Wood," in Wood Science, vol. 11, no. 2, (October 1978): 86-90.
  5. Flyate, D.M., and Y. B. Grunin, Zhurnal Prikladnoi Khimii, vol. 47, no. 12, (December 1974): 2739-2741, English translation by Plenum, NY, 1975.
  6. Stolow, N., Controlled Environment for Works of Art in Transit. London: Butterworths, 1966.
  7. Michalski, S., "Paintings - Their Response to Temperature, Relative Humidity, Shock, and Vibration," in Art in Transit, 223-248. Washington, D.C.: National Gallery of Art, 1991.
  8. McCormick-Goodhart, M., "The Allowable Temperature and Relative Humidity Range for the Safe Use and Storage of Photographic Materials," in Journal of the Society of Archivists, vol. 17, no. 1, (1996): 7-21.
  9. Mecklenberg, Marion and Charles Tumosa, "Environmental Effects on the Structural Response of Painted Wooden Surfaces," in Abstracts of Papers Presented at Painted Wood: History and Conservation, Williamsburg, VA, (November 11-14, 1994): 18.

Stefan Michalski
Senior Conservation Scientist
Preventive Conservation Services
Canadian Conservation Institute
1030 Innes Road
Ottawa K1A 0M5

Barbara Cumberland

The Division of Conservation (DOC), Harpers Ferry Center, provides conservation services for museum objects owned by the U.S. National Park Service (NPS) which are exhibited in visitor centers, museums and furnished historic buildings across the United States. We temporarily store these objects at our facility where they undergo exhibition preparation before they are returned to their respective sites. An IPM program (Integrated Pest Management) is critical at the Harpers Ferry Center in order to eliminate the threat of infestation to the wide variety of objects which come to the facility.

The DOC has implemented the NPS Service wide program of IPM which is mandated for all Federal agencies. Our IPM program, begun in 1991, employs a variety of methods to prevent and solve potential museum pest problems in the most efficient and ecologically safe manner without compromising the safety of staff or collections. The program includes monitoring and pest identification, inspection, habitat modification, good housekeeping, treatment or management action, evaluation and education. The following discussion outlines the IPM program adhered to by the DOC at the Harpers Ferry Center.

Staff roles

For our IPM program to be effective, all staff members must actively participate. The following is a description of staff roles:

DOC IPM Coordinator

IPM Assistant in Registrar's Office

DOC Staff

Building Maintenance Staff

Service wide IPM Coordinator (off-site within NPS)

Limiting pest access and harborage

A primary objective of our staff's IPM activities is to restrict pest entry and to limit what pests need for survival: food, water, and harborage. Inside the building, enclosing objects in storage cabinets is the first defense against pests gaining access to objects. Also, food and eating is limited to one area of the building, the lunch room. Houseplants and flowers are not allowed in the conservation lab's building, because they provide food, water and shelter for pests. For example, adult carpet beetles usually feed only on pollen from flowers, while their larvae feed on wool, silk, taxidermy specimens, and other proteinaceous materials, found in our museum collections.

Good housekeeping and sanitation is essential to any IPM program. Insects hide and breed in cracks and crevices and in the dust that collects there. The facility building is routinely vacuumed on surfaces and in crevices to remove accumulated dust, adult insects, larvae and eggs. Clutter is eliminated. Any water leaks or moisture problems in the building are located and corrected, because water attracts pests and is necessary for them to survive.


Monitoring provides baseline and ongoing information on the biological activity in the facility. It provides important pieces of information: where the pests are, how they came into the facility, and why they are surviving. Monitoring relies on such techniques as direct observation, passive trapping and routine inspections.

A basic and important monitoring activity is routine inspection for pest evidence throughout the building, especially around artifacts. Museum objects that are particularly susceptible to or attractive to a certain pest should be inspected monthly (e.g., freeze-dried taxidermy specimens for micro-organisms, dermestids and moths; books for silverfish and booklice). Incoming artifacts and supplies are carefully inspected on arrival at the NPS facility.

Various kinds of traps are used for passive trapping in and around collections and the building as well. Generally we use non-baited sticky traps to monitor most areas in the facility. In certain areas where organic objects are located, we also use sticky traps with commercially available pheromone lures for webbing clothes moths and cigarette beetles, and an experimental pheromone lure that is available for varied carpet beetles. The traps are dated and numbered, with the numbers keyed to a specific location on the building's floor plan. They are inspected monthly by the IPM Coordinator or an assistant. The traps, unless empty, are discarded after each regular monthly inspection so that the insects are not counted more than once, or become attractive as food sources for other insects or rodents. Since the conservation labs moved into this new building in 1992, we inspect approximately 130 pest traps around the building. In addition, mouse snap traps are only used for monitoring in areas where evidence of rodents is discovered through routine inspection (droppings, nesting materials, damage to supplies, etc.).

The data collected with our IPM monitoring program is recorded on a computer database and evaluated on a regular basis. Computer reports can be structured in a number of ways, including graphs showing population patterns and life cycles over the years so that the IPM program becomes anticipatory. Monthly computer reports are circulated to staff members each month so they can address the pest problems found in their labs and work areas. The IPM Coordinator dedicates about one day per month to routine pest inspections, monitoring, recording data and circulating reports to staff.

Infestation control

Objects suspected of infestation are first isolated to determine the extent and source of the infestation. The pest must be identified as well as its stage of development before control strategies can be instituted. For example, small objects are sealed in heavy polyethylene bags with a sticky trap enclosed. Large wooden objects, which show evidence of wood boring beetles are stored undisturbed on a large sheet of white or black paper and sealed in polyethylene. In time, accumulations of wood dust or frass appearing on the colored papers would indicate an active infestation. Pest evidence on objects is recorded on a "Pest Incident Report," (see below) which is filed with the object's treatment records and/or registration records. A copy is also given to the IPM coordinator who incorporates this information into the IPM monitoring database because it can provide clues as to whether an infestation originated with the object or with the building. Thresholds of pest activity are determined within the facility.

Threshold refers to the point in the size of a pest population at which some management action must be applied to prevent the pests from reaching the injury level. Injury level refers to the point in the growth of the pest population when pest numbers are sufficient to cause an unacceptable degree of damage for a specific site. In an IPM program, the objective of management action is to suppress the pest population below the prescribed action threshold level, rather than attempt eradication of the pest. Thresholds within the facility depend on the species and location, but if pests are found on or near any museum object, the threshold level has been reached and management action must be taken.

Pest management strategies or options must be evaluated. Questions to ask are: Are the pests in question considered to be "museum pests"? Are the pests in proximity to locations where objects are stored or worked on? Is mechanically removing the pest enough to arrest the infestation? Will cleaning stains from artifact materials eliminate the pest problem? Will freezing or fumigation with atmospheric gases (e.g., nitrogen, carbon dioxide, argon) arrest the problem? Will building alterations such as screening and caulking pest entry points and eliminating areas of pest harborage control the problem? What is the least damaging pest control method for the objects, staff, and the environment? Are there environmental effects of treatment actions to consider? What is the most effective approach to managing the problem or arresting the infestation?

Options for chemical control of infestations are becoming increasingly limited. Because of the toxicity levels of commonly used fumigants, few fumigants are now available or recommended for museum use. In addition, research now indicates that chemical fumigation of artifacts can negatively affect object materials and cause chemical alteration of their components. Pesticides, especially those with residual effectiveness, can pose continual health risks for staff members who work with objects, such as ethnographic objects and taxidermy specimens commonly treated in past years with arsenic or mercuric chloride. DOC has not used any chemical fumigation of objects in the past nine years and has relied on non-toxic alternatives such as freezing.


The IPM Coordinator carefully records detailed information in the IPM notebook about pest control activities in the DOC. It contains the monthly computer listing of pests observed through monitoring, records of pest control activities (special trapping, building modifications, preventive measures, pesticides used, freezing or other methods of pest eradication), graphs showing pest activity over time, Pest Incident Reports indicating pest activity observed on museum objects, IPM correspondence, pesticide use clearance, and any summary reports to the staff. The IPM program is then critically reviewed to determine how it can be modified to prevent infestations from occurring in the future. Findings are shared with other staff (maintenance, designers, interpreters, curators) and visitors.


  1. National Park Service, Integrated Pest Management Information Manual, Second Edition, Washington, D.C.: GPO, 1994.
    This is a very useful aid in determining management options for infestations of specific museum pests.
  2. Story, Keith O., Approaches to Pest Management in Museums, Washington, D.C.: Conservation Analytical Laboratory, Smithsonian Institution, 1985.
    This book describes cultural approaches, mechanical approaches, trapping and chemical approaches for infestations of specific museum pests. Non-chemical and low risk alternatives are tried initially, with the exception of an infestation where threshold levels indicate that chemical treatment is the best or only option.
  3. National Park Service, "Biological Infestations," in Museum Handbook, Part 1, Museum Collections, 5:1 - 44. Washington, D.C.: GPO, 1990.
    This book is used as our reference for the IPM approach to pest control for museum collections in the NPS. It may be purchased for $36.00 ($45.00 foreign) through the Superintendent of Documents, P.O. Box 371954, Pittsburgh, PA, USA 15250-7954.
  4. National Park Service, Natural Resources Management Guideline, NPS-77, Washington, D.C.: GPO, 1991. Provides guidance and a specific structure for obtaining approvals for any pesticide use within the NPS system.

Barbara Cumberland
IPM Coordinator
National Park Service
Division of Conservation
Harpers Ferry Center
P.O. Box 50
Harpers Ferry, WV 25425-0050


Park: _________________________
Object: _______________________ 
Cat#:  ________________________
HFC#: _______________________
Date: __________________________
Examiner: ______________________
Object location: _________________________________________________________________________________
Materials affected: _______________________________________________________________________________

Pest Observation

Number of pests observed: ____________________  Living ________________  Dead
Identification source: ______________________________________________________________________________


______ powder post beetle
______ termite
______ dermestid beetle
______ undetermined
______ cigarette beetle
______ fungal growth
______ drugstore beetle
______ clothes moth
______ silverfish
______ cockroach
______ other: ______
______ spider
______ fly

Evidence Observation

______ losses
______ odor
______ holes/tunnels
______ staining
______ droppings
______ cast larval skins
______ frass
______ specks
______ webbing
______ cast skins
______ other: _______
______ egg casing
______ castings
______ carcasses

Management Action Taken

___ mechanical cleaning: _________________________________________________________________________
___ freezing (list duration and dates): ________________________________________________________________
___ fumigation (list fumigant): ______________________________________________________________________
___ isolation (list method): ________________________________________________________________________
___ object requires follow-up inspection (list frequency): _________________________________________________

Additional Comments


The Ethnographic Conservation Newsletter of the Working Group on Ethnographic Materials of the ICOM Committee for Conservation is available free of charge to those with a professional interest in the care and research of ethnological collections. It is published twice a year with a mailing in October and April.

Authors are asked to submit articles in English only. A Guidelines for Authors is available from the address below or from your regional coordinator. We request that contributions be provided in a typed format - typed in standard typeface, on 8 1/2 by 11 white paper, one side only, and double-spaced. Electronic contributions via Internet, ECN@nmnh.si.edu, will also be accepted, but submissions must be sent in an E-mail message in ASCII text format ONLY and not more than 80 characters wide.


The editors have produced an on-line version of the Ethnographic Conservation Newsletter, numbers 13 through 19. Because the nature of the Web audience is vastly different from the original audience of the ECN, the editors have taken the liberty to protect contributors from being potentially inundated with inquiries. Therefore, contributors who have private practices in their homes will have only their names published. Anyone interested in contacting these authors should direct their inquiries to the editors rather than the authors. Those contributors with practices within public institutions will have the names and street addresses of the institutions published. Should a contributor prefer not to have his or her article published on the Web, please contact the editors.

Anthropology Conservation Laboratory
National Museum of Natural History
Smithsonian Institution
MRC 112 10th and Constitution
Washington, D.C. 20560
Fax : 301-238-3109

Please forward contributions to the newsletter through your regional coordinator. All submissions must be received two months before the mailing date for inclusion - by August 1 for the October mailing and by February 1 for the April mailing.

Permission to reprint ICOM Ethnographic Conservation Newsletter contributions may be obtained in writing from the Editors.

For information regarding the International Council of Museums (ICOM), and the ICOM Committee for Conservation, please contact:

Maison de l'UNESCO
1, rue Miollis
75732 Paris cedex 15
Fax: 33(1)43-06-78-62

The Ethnographic Conservation Newsletter provides a forum for ideas, but this does not imply an endorsement of any products or procedures; it cannot, therefore, be responsible for the recommendation or application of same. This same principle of neutrality applies to individuals and institutions; the Newsletter is not a judge in regard to either the aforementioned or of related articles published herein. This information presents brief views of issues related to ethnographic conservation, and is not intended to replace the advice of a conservator with respect to particular circumstances.

Top of Page

This page created by D. Nguyen
Updated August 31, 1999