Volume 13, Number 1, Jan. 1991, pp.21-23

Insect Traps in Conservation Surveys

Providing museums with accurate conservation survey information can enable the institution to make informed decisions about directing their limited resources to the greatest benefit of their collections. In conducting a conservation survey, one of the areas of concern for museums in tropical climates, and for most museums in the western United States, is the control of insects that cause deterioration and damage. One method for identifying both the scope of the insect threat to a museum and the causes of that threat is the proper use of monitoring traps.

It is important to recognize that insects are organisms which require a fairly narrow set of environmental conditions in order to survive. We can use our knowledge of these required conditions to focus our monitoring and pest-control attention toward potential dwelling, feeding, nesting and aggregating areas, as well as migration pathways.

It is extremely unusual for the collection area to be the primary environment for an insect population. Primary environments are more often uncontrolled mechanical rooms, attics, crawl spaces, kitchens, supply storage rooms, or areas along the building perimeter or facade with accumulated plant debris, animal nests or accumulated moisture with mold and algae growth. These areas must be monitored for insects--along with collection areas and galleries--if we are to find out whether a site has an insect problem, and if so, what that problem really is.

In most survey and conservation-assessment situations, it is easy to obtain annotated floor plans of the museum and collection areas well in advance of the on-site inspection. It becomes a relatively simple matter, therefore, to request the placement of a series of insect traps which can be left in place for perhaps 4 weeks prior to the conservation survey. Upon arriving for the conservation-assessment survey, information can be obtained from the monitoring traps about the actual presence of insects instead of simply looking for damage to collections. The identification of the insects, combined with the location and frequency of their occurrence, will help identify architectural deficiencies or problems with housekeeping or maintenance procedures which may truly be the cause of the problem. This can then enable the conservator to suggest steps which will help the museum manage the problem properly.

The Pacific Regional Conservation Center (PRCC) at the Bishop Museum in Honolulu has been using a number of insect monitoring traps for the past 3-1/2 years. We typically use three different traps in a conservation survey. These are: Yellow Sticky Strips, Serrico cigarette beetle traps, and Storgard traps.

The inexpensive Yellow Stiky Strips are 11-1/2 in. x 6 in. thin sheets of bright yellow plastic, coated on both sides with a non-toxic, non-drying sticky goo. They come in packs of 50 and are covered with a removable waxed-paper backing to make them easier to handle. They have a hole at one end from which they can be hung. They can also easily be cut with scissors to any size or shape needed. When hung in corners and from light sources, they can monitor insects that fly and are attracted to light and pollen, or who aggregate in corners. Yellow Sticky Strips taped to the floor and baited with a small amount of fish meal (fish food, acquired from pet stores) are also very useful traps.

When placed on the floor, only the top side of the trap has its backing paper removed. The edges can be taped down with drafting tape, which is easier to remove than masking tape. In this application, the custom-cut Stiky Strips can be placed along baseboards, under storage and exhibit furniture, on window sills, near floor drains and in cabinets. It is a good way to trap a wide range of museum insect pests, such as silverfish, clothes moths, dermestid beetles and their larvae, booklice, roaches, crickets and many others.

Serrico cardboard traps fold and lock into a box-shaped, 3-1/2 in. wide x 7-1/2 in. long x 1/2 in. high, low-profile covered insect environment. They are placed upon the floor, under storage and exhibit furniture, on storage shelves and hung from light fixtures. The inside surfaces of the traps have a thin plastic sheeting covered with a coat of sticky, non-toxic plastic goo. This trap is most commonly used with a pheromone lure known as a "Lasio Lure," specifically for cigarette beetles. The presence of this pheromone does not seem to affect the trap's ability to catch the full range of ground-crawling insects. The only trick in using the trap is to be totally compulsive about making the folds properly. Most conservators find this to be of no difficulty.

Storgard traps, like the box-shaped Serrico traps, appeal to the insects' love of a closed, protective environment. They are made of corrugated cardboard, a favorite home for a great number of insect pests including roaches, silverfish, booklice and cigarette beetles. These traps fold neatly into 3-1/2 in. x 3-1/2 in. x 3/4 in. thick blocks and have a small plastic trough inside which holds a circle of blotter paper, upon which is dropped an oily food bait. The bait attracts insects that require proteins and essential salts for nutrition. The bait coats their breathing apparatus, immobilizing and smothering them within the trap.

At the PRCC, we originally provided and placed insect-monitoring traps as part of the conservation survey service we provide to museums in our region. But we have moved away from this approach and now spend some time informing the collection manager or curator what traps to purchase, where to order them and how and where to place them properly. We indicate on floor plans where the survey traps should be placed, and we have the institution set the monitors well in advance of our arrival. When there is no staff member to set up traps beforehand, we place them during the on-site visit and indicate on the floor plan where they are located. It is, or course, important for whomever places the trap to write or otherwise record on the trap the date it was set, the location where it was placed, as well as the date collected. Preprinted self-adhering labels are particularly useful in this context, but drafting tape will also work. Staff and volunteers are shown the traps so that they can recognize them and avoid disturbing them in their daily routines. Later, in about a month, we ask the staff to enclose each trap in a polyethylene bag and send them to the PRCC lab for identification of the insects and analysis of the site's insect situation.

Taking a look at some of the more common museum insect pests, we can gain some insights into the usefulness and placement of the traps.

Lasioderma serricorne (cigarette beetle) and Tricorynis herbarium (herbarium beetle) tend to eat plant leaf materials, but in Hawaii they have been known to feed on most types of cellulosic material, including fabrics, paper, leaf, rush, cane, hardwoods and barks.

Research on their habits and life cycle indicates that areas that warm to 65 degrees F or more, and which tend to have higher humidities, will be desirable aggregating areas for cigarette beetles. This includes south and west facing external walls or mechanical rooms which are not air-conditioned, or which have heat-producing machinery. Room corners, windows and baseboard areas under shelving and storage furniture provide necessary protection. Grounds surrounding buildings that have plant debris or accumulated leaves on roof tops or in gutters can also harbor populations which can migrate into adjacent damp walls. Pheromone Serrico traps along these protected floor areas and Yellow Stiky Strips near light sources appear effective as both monitors and partial control measures for cigarette beetles.

Dermestes maculatus (hide beetle), Trogoderma anthrenoide (museum beetle), Trogoderma variable (warehouse beetle), Attagenus megatoma (black carpet beetle), Anthrenus sp. (common, varied, and furniture carpet beetles) commonly damage proteinaceous materials, such as skin, hair, fur, and feathers. They are frequently associated with bird nests, old wasp nests, spider webs, bee nests and dead insects, and these beetles in the adult phase are also found in association with flower pollen. The attraction of adults to pollen is one reason why flowers in galleries and collection areas can pose a significant threat to collections. Larvae are strongly attracted to dead insect remains.

Dusty baseboards and spaces under storage furniture are good locations for traps, as are areas near cracks in walls and floors, attic spaces, and under door jambs and window sills. Look for spider webs, dead ants, gnats or other insect debris as an indicator where traps should be laid. Yellow Stiky Strips taped to floors or near windows and hung near light sources serve well as monitoring traps. Serrico traps also work well in this regard. Storgard traps have also frequently trapped larvae along migration paths.

Silverfish, Lepisma saccharina, are extremely common and feed on cellulosic material, sizings on paper, book bindings, glues, pastes, rayon, grains, skins and leather, particularly when they are soiled. Adults generally live in excess of 3-1/2 to 5 years. These insects have almost no sense of smell, so food baits and pheromones are ineffective. Knowing their habitat preferences is the only way to effectively trap them. They like warmer conditions, but not too warm. When conditions are either too cold or hot outside, they look for more moderate conditions inside a building. Baseboards and floor and wall cracks are favorite passageways, so again, look for silverfish around exterior walls.

If you know that silverfish are present in or on your storage furniture, Storgard traps may be appropriate. The corrugated cardboard provides cover, food and the small spaces which can provide these nearly blind insects the tactile stimuli they need to feel safely covered. Floor Yellow Stiky Strips and Serrico traps at areas of migration, particularly at south and west facing exterior walls, also appear to be useful.

Liposecelis sp. (psocids or booklice) are fungi feeders. Large populations usually indicate that moist conditions conducive to fungal growth are present. These insects themselves will not damage collections but their droppings and remains become the primary food source for carpet beetle family members. If psocids are present, the collection areas should be inspected for fungal growth as molds and fungi can cause structural damage and visual disfiguration to artifacts. The surrounding structure should be inspected for the source of moisture and/or high humidity. Floor Yellow Stiky Strips and Serrico traps along baseboards and under storage furniture appear to be the best monitoring traps for these small insects.

Tineola bisselliella (webbing clothes moth) and Tinea pellionella (casing clothes moth), as well as Tineola walsinghami (plaster bagworm) all feed on proteinaceous materials such as skin, leather, hair, wool, silk, feathers, baleen, and will even feed on non-protein materials such as cotton, linen and paper when there are essential salts present in residues of food, perspiration or processing chemicals.

Yellow Stiky Strips baited with fish meal and taped to the floor are very useful traps. Traps placed in the center of rooms under storage shelving help to locate any moths already in collection items. Baseboard and corner floor traps are useful to help identify resident crevice populations.

When insects are trapped and collected, identifying them with the aid of a little magnification is relatively simple. With just a few sessions working with an agricultural extension agent or museum entomologist, the frequently occurring insects can be identified using standard keys. Agricultural extension services and museum entomologists are often very willing to identify unusual specimens for you, particularly if you allow them to keep the specimens that are weakly represented in their own collections.

Conservators will undoubtedly develop an affection for one kind of trap over another, especially if they obtain more exciting results with a certain trap. Each trap, however, has its own advantages and all of them have trapped many insects in museum environments for me. I find that the use of all three traps is the best approach.

Supply Sources

Yellow Stiky Strips, manufactured and distributed by Olson Products, P.O. Box 103, Medina, Ohio 44258; 216/723-3210. Approximate cost: $50 for a box of 50 traps. Also available: 3" x 5" traps, box of 100 for approximately $25, and Yellow Ribbons, 1-2/4" wide by 27" long, coated on one side only, box of 100 for approximately $15.

Serrico Insect Trap, manufactured by Fuji Flavor Co. Ltd., Tokyo, distributed by Insects Limited, 10540 Jessup Blvd., P.O. Box 40641, Indianapolis, IN 46280, 317/846-3399. Approximate cost: $55 for kit containing ten traps and ten pheromone lures.

Storgard Insect Monitors, manufactured by Trece Corp., Technical Assistance: Ms. Autumn Stark, P.O. Box 6278, Salinas, CA 93912, 408/758-0205; distributed by Insects Limited (see address above). Approximate cost: $58 for a kit containing ten traps, "Pit Fall" food attractant and 10 pheromone lures for the complex of trogoderma beetles. Trece Corp. will introduce a carpet beetle pheromone monitor in 1991; contact Ms. Stark for info.

Selected References

Ebeling, Walter: Urban Entomology. University of California, Berkeley, 1978. Bibliographies.

A large book oriented to industrial and commercial applicators. It is very useful because of the descriptions provided about insect habitats and behavior. Many control recommendations are outdated or inappropriate for use in museums.

Mallis, A.: Handbook of Pest Control. 6th Edition. Franzak & Foster Co., Cleveland, 1982.1101 pages. Bibliographies.

A large general work, again with a chemical commercial control focus. This book also provides useful information relating to insect behavior, habitats, life cycles and food sources. Much can be learned about making environments more hostile to insects by reducing or eliminating required environmental conditions.

Metcalf, C. L., W. P. Flint & R L. Metcalf: Destructive Useful Insects, Their Habits and Control., 4th Edition. McGraw-Hill Book Co., New York, 1962. 1087 pages.

Treatment advice is grossly outdated, but the information on the biology and life cycles of pest insects is invaluable and often not repeated elsewhere.

Story, Keith: Pest Management in Museums. Conservation. Analytical Laboratory, Smithson Smithsonian Institution, Washington, DC, 1985. 165 pp. Outstanding bibliographies in each chapter.

An extensive overview of pest management in museums with descriptions of chemical and non-chemical methods. Some control material outdated.

Zycherman, L.A., editor: A Guide to Museum Pest Control. Foundation of the American Institute for Conservation of Historic and Artistic Works and the Association of Systematics Collections, Washington, DC, 1988. 205 pages.

A good contemporary overview of pest management in museums. Excellent bibliographies.