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Pest Management: a Perspective

Bernard Kertesz.


Part of a cultural collecting organisation's risk management strategy should be to include a pest management program. The term "management" is appropriate since pests are an ever-present threat and their control is only as good as the effort put into the process.

The primary control strategy in pest management is good housekeeping. This is the foundation stone in the Integrated Pest Management (IPM) strategies adopted by many cultural collecting institutions (CCIs), including the Australian War Memorial. IPM might be a daunting sounding concept but it's really just the harnessing of non-chemical approaches to minimise the use of chemical ones. No pesticide can offer guaranteed long term freedom from pest species except of course for the controversial (and banned) organochlorines or arsenic dust.

IPM was developed in the agricultural industries to minimise the level of pesticides used in crop production. In cultural collecting institutions it's the modification of physical aspects of the building and of cultural attitudes in staff to render the environment less attractive to pests. A good overview of the available resources on IPM is at the "CoOL" (Conservation On Line) website,

Like any good risk management strategy IPM is an approach whereby the response is tailored to the risk. To do a proper risk assessment a CCI would need to survey its buildings fairly intensively. It's therefore advantageous (if not essential) for collection managers to have a good working relationship with building maintenance personnel. There are clear, strategic advantages in having not only a good understanding of the nature of the threat, but also of how the building envelope and its systems might exacerbate this threat or help mitigate it.

What's a Pest?

If an insect is noticed, first decide if it is a genuine pest or just a nuisance. Flies are a nuisance and can cause some spotting but are not consumers of collections. Spiders are often considered as a nuisance around window frames but are not pests of collection materials and actually contribute some useful biological control functions. The major pests of collection materials, silverfish, carpet beetles, clothes moths, cockroaches and many species of borers, are common world-wide pests which are also very common in the household environment. Other animals such as rats, mice and even to some extent pigeons are also cosmopolitan pests but these are generally disposed of by trapping; not generally a useful option with insect pests.

At the AWM's Treloar annexes in Mitchell (a Canberra suburb), experience shows that the primary hazards are posed by carpet beetles (wool, fur, feather and hide pests) and mice (primarily as autumn/winter intruders from the surrounding paddocks). A useful Australian text on such "urban" (as opposed to agricultural or silvicultural) pests is Urban Pest Management in Australia by John Gerozisis and Phil Hadlington (2001, UNSW Press). If you're not able to identify the insect and it's causing you concern, it may be worth contacting CSIRO Entomology or entomologists in a local museum or university. There is often a fee for such services. Whatever the outcome, file the information for future reference. Some insects such as crickets and burrowing stink bugs are seasonal and appear in conspicuous numbers.

If you've identified the organism as a pest, concentrate on physical methods and cultural methods to catch, disinfest and exclude them.

Integrated Pest Management

The goal of IPM is to keep insect and other pest numbers down whilst at the same time maintaining the health and safety of staff and collections. This is achieved by lowering a building's vulnerability and making it less attractive for pests to remain. Awareness raising is important in increasing the vigilance of all staff to the nature of what is, after all, a collective responsibility. The IPM approach acknowledges the inability of pesticides to totally eradicate all pests and the irresponsibility of a "nuke 'em" pesticide policy.

Controlling pests requires physical and cultural modifications before chemical means should even be considered. There are some fairly straightforward physical modifications that can be used to minimise the pest risk, including;

  • the sealing of interior and exterior cracks and crevices and secure netting of breather holes
  • the sealing of pipe and ducting access holes,
  • installation of secure window and door seals,
  • ensuring that guttering and eaves and building cavities are kept clear of rubbish, birds' nests and other detritus,
  • stabilisation of the buildings environment so that conditions remain moderate,
  • maintenance of the building fabric to avoid leaks,
  • rising damp and similar conditions that attract pests.

Even something as seemingly inconsequential as the external security lighting can make a difference. To avoid actively attracting pests into a building, it's advisable to install lighting which has low emissions in the ultra-violet (UV) end of the spectrum. The high UV emissions from sources such as mercury vapor lighting are very attractive to many night-flying insects and are actually used by entomologists in nocturnal insect traps. The yellowish glow of low-pressure sodium lighting is much safer (and incidentally causes less light pollution). Shining the security lighting at the building and not mounting them on the building also helps.

There are occasions when the building fabric is "breached"; one of these is when materials are introduced into the building. Incoming materials whether new acquisitions, office consumables, building materials or pot plants can all carry in pests. These pests may come in as larvae or adult insects but also, less conspicuously, as eggs. Those incoming materials which are suspect, should be received in an isolable, "dirty" area where they can be inspected and, if necessary, disinfested. Silverfish are commonly introduced into buildings via corrugated cardboard boxes, the corrugations forming favoured nesting sites.

Any cultural collecting organisation that is serious about risk minimisation has to deal with the issue of risk containment. If certain practices attract pests then strategies need to be developed to contain that risk. The commonest of these practices are food consumption, waste management and the broader issue of cleaning. Food should only be consumed in one area, ideally one which is easily contained from the rest of the institution. The practice of eating in offices or work areas where collections are handled or processed makes no sense, particularly when one considers that the risk is multiplied by the number of work stations in the organisation. Maintenance of hygiene is nearly impossible under such circumstances. Similarly it's important that waste, particularly food scraps and spillages, must be promptly contained and disposed of, out of the building, at the close of each day. Food which is left in a building after hours is best stored in a fridge or closed container where it's inaccessible to "night visitors". During a routine pest inspection, an apple which had been left on a desk for a few days was inspected and found to have been eaten through to the core, from behind. The apple's owner hadn't noticed.

The cleaning program in a building can have a profound impact. Insects don't like to be disturbed but do like the day's detritus; not just food but also dust and fluff. One way to increase the effectiveness of an organisation's cleaning dollar is to have office and storage furniture which is readily accessible underneath and behind. This access should be a feature of the furniture's design and of a cultural attitude to clean and tidy workplaces. Canberra has a chronic problem with migrating Bogong moths throughout the spring months and often also in the late summer. These moths easily access most buildings and hide behind cabinets, bookshelves, solid desks and also behind the detritus of disorganised and cluttered work spaces. Unfortunately Bogongs often also die there and, in the relative shelter and darkness that most furniture provides, they constitute the primary food source for serious pests such as carpet beetles and clothes moths. If the dead moths can't be cleaned up, serious infestations may result.

Areas used as non-collections "storage", especially of rarely used materials, tend to degenerate to a stage where they are little more than dumps. It is not surprising that they are so attractive to vermin. There wouldn't be an institution in existence that hasn't had just such a space colonised by rodents. Again it's worth stressing the obvious, the major thrust of the IPM strategy is good house-keeping.

Pest Surveys

Surveys are essential to provide baseline data on a building's susceptibilities and to establish trends. They also help you to become very familiar with your building. Surveys can be conducted actively with a torch and notebook or by stealth. Passive surveys, conducted with traps such as sticky cockroach traps, are a cheap and readily available way of sampling the fauna. They should be placed in key suspect areas such as in tea rooms, quiet corners such as those under or behind furniture, in cupboards and in storerooms. It's important to note when and where such traps are installed. One should expect a seasonal variation in most pest numbers; absence of pests in one season's trapping is no guarantee of their absence in the building.

Active surveys are carried out on both the interior and exterior of the building. Make note of what's crawling (or dead) on window-sills and around doorways and in refuges such as ceilings, wall cracks, pot-plants, behind or underneath furniture and in rodent baits. Rodent baits are foodstuffs after all and are invariably harmless to insects. Neglected rat poison has supported many an infestation of carpet beetles. Look for birds nests when inspecting ceilings or eaves. Items on display require special checking especially woollens, animal skins and fur items. Look particularly beneath the item, under lapels, in pockets, inside linings and hatbands, in fact anywhere that pests may be inconspicuous.

The kinds of insect material that are found in a survey can range from whole insects to body parts and frass (excreta). Frass, particularly from wood borers, may be found in the immediate vicinity of wooden objects. Borer-infested wood often has "flight holes", small round holes ranging from about 1 mm up to 10 mm, depending on the borer. Frass and flight holes can be used for species identification. Be aware however that holes in timber don't necessarily indicate a current infestation although some borers can take years to complete their life cycle. On one such active survey, large, 20mm long, black beetles were found wandering the floor of a storage area. They turned out to be large auger beetles (Bostrychopsis jesuita) that had emerged from tropical timbers, purchased by the organisation's model builder, 6 years earlier. They posed no further threat of infestation in the Canberra climate but caused some anxiety nevertheless.

Keep an eye open also for mouse droppings; they're easily missed. Useful equipment to take on a survey would include some small bottles or specimen vials, a torch, brushes, plastic bags, a notebook and a camera.

With all such data collection it's important to always prepare gathered information into reports. The survey results gathered will provide a history of the collections environment; the variety of pests, their distribution in space and time, their abundance and indicate the associations of insects and other pests. These associations can also be diagnostic of environmental conditions. For example, slugs and slaters in a building indicate damp and high humidity. Similarly, booklice live on fungi that they cultivate on paper and other materials.

The surveyed insects (and other pests) will fall into four basic categories;

  • those which attack collections, e.g. carpet beetles and silverfish,
  • those which stain collections, e.g. fly-spotting, cockroach saliva and faeces,
  • organisms that blunder in causing occasional damage and sometimes attract or transport in the above pests, e.g. Bogong moths, mice, birds, possums and of course, humans and
  • those which are predators e.g. spiders, tiger-beetles & rodents.

Chemical Treatments

If good housekeeping doesn't work and your inspections indicate that the pest is not under control or an infestation arises, it's probably time to attempt some chemical control. The fragility of most heritage collections and the fact that they are handled, does however seriously limit chemical methods for control. Many of the pesticides in commercial use are very much less toxic than those formerly used, however care should still be taken. Some are very damaging to natural environments because they are very potent poisons for the invertebrate organisms that form the basis of all food chains. They should never be disposed of into waterways.

If you do have a pest problem, then I'd advise calling in a pest controller. It is best however to have a rough idea of what your problem is and where it's focussed. No pest controller will know a building as well as its inhabitants. They might know what areas to expect problems in (e.g. kitchens, sub floors), but any information you can offer will help. In particular, give as much information as possible outlining the kind of problem you wish to solve, the affected areas, the sensitivity of your collections and any other information you feel might assist the operator to target the problem. If you can't identify the insect but can point out the damage and it's location then that is of great assistance to a pest controller. It's important that the health and safety considerations are addressed. When you ask a pest controller to quote for a treatment expect them to supply a full schedule of proposed pesticides, their application rates and to provide Material Safety Data Sheets (MSDS) on all substances. A word of warning; the MSDS lists safety precautions, spill procedures and so on, for stock solutions. These don't necessarily translate so severely to the diluted application. A common skirting board spray, Deltamethrin, has an LD50 of 135-5,000mg/kg (depending on the formulation) but is used at a concentration of 0.015% or less. Gerozisis and Hadlington's book has a reasonable and useful outline of the approach a responsible pest controller should take in dealing with a pest problem.

The choice of treatment time and frequency are very much a consequence of what the pest is and how widespread. Most pests are inactive over winter, however silverfish and textile pests are at it all year round. The usual strategy for dealing with such pests is to use a "knock-down" pesticide such as a pyrethrin followed by a skirting board spray of a synthetic pyrethroid. A brief note about synthetic pyrethroids; these are synthetically manufactured analogs of the natural, Chrysanthemum extracts. They generally have a very high toxicity to insects but a low mammalian toxicity; Permethrin for example has an oral (mammalian) LD50 (the estimated amount, given by mouth, which will kill 50 of the test animals, usually mice) of 10,500 milligrams per kilogram of body weight; the much nastier and commonly used organophosphate, dichlorvos has an oral LD50 of 56-80 mg/kg. Domestic pest control applications invariably use these pyrethroids; most surface and aerial sprays available in supermarkets use them in various combinations and with synergists (low toxicity substances that enhance the pesticide's effectiveness at low concentrations). Although synthetic pyrethroids are extremely toxic to invertebrates and are a serious hazard to the ecology of waterways, they tend to be readily broken down by light and soil microorganisms within a few months.

A typical pest problem, for example, might be one where rodents and silverfish need management. A pest controller might deal with this problem by;

  • fogging with a non-residual pesticide like pyrethrum to get an immediate knock-down effect; sometimes dichlorvos ("Insectigas") is suggested but this is hazardous to many collection materials,
  • spraying skirting boards and thresholds with a residual, synthetic pyrethroid (maximum efficacy about 3 months); these replace the very much nastier organophosphates and carbamates,
  • permethrin dusting powder, a very low toxicity synthetic pyrethroid, is dusted into building crevices and around pipe gaps etc in walls; areas which are popular refuges for insect pests,
  • placing baits or traps out for mice and rats.

These strategies tap into the behavioural habits of pests. Most pests will avoid crossing an open room but prefer to sidle around the edge of it and pause behind cover. Insects therefore pick up tiny amounts of pesticide as they wander along the edge and skirting boards of a room. Since they are also fastidious about cleanliness, they're always ingesting tiny amounts of pesticide during grooming. Mouse baits and traps tend to be placed where the rodents might pause behind furniture and also in warm spaces where they prefer to nest; behind fridges, freezers and hot water heaters.

A word of caution; it may be advisable to schedule treatments for after hours or on weekends. This is basically to keep staff and external clients away from the process. Many modern pesticides are not hazardous during application; skirting sprays are applied locally in a water spray without misting and the water diluent dries off rapidly. The sight of spraying can however generate real concerns in staff, a legacy of the bad old "overkill" days. Before any treatment is carried out in a facility, all staff should be notified of the upcoming procedure (even if it's done out of hours) with any advice on precautions to be taken. It is essential that the health and safety structures are notified. If concerns are expressed then it's the health and safety representatives and the OH&S Committee that will be asking questions about the neglect of the duty of care provisions of the legislation. Out of hours staff such as cleaners and security must be warned of the nature of the spraying and security must be advised of the safety precautions after any fogging treatments.

It's best to escort the contractor around. This not only provides for feedback during the treatment, but allows one to note the rodent bait locations and to familiarise the contractors with the nooks and crannies the building. Contractors inevitably leave any fogging or misting till last since the building needs to then be left vacant for at least four hours (overnight is better) until the pyrethrum breaks down. Note that the contractor then posts a warning (with the time of treatment and exclusion period) on the building's entrances to prevent accidental access. If any person is required to enter the building before the exclusion period ends appropriate respirator equipment should be used. The education of pest controllers is not limited to the building's layout; the contractor's often not aware of the collection's sensitivities. A common problem with rodent baits is that the level of proteins and carbohydrates in the bait are well within the nutritional preferences of carpet beetles. When inspecting a rodent bait station it's therefore important to stress that any bait infested with carpet beetles be disposed of, including the bait box, and the area treated. Typically, a quarter of bait stations can be so affected and a contractor who is inspecting the bait for signs of rodents may completely miss a carpet beetle infestation. A further advantage in accompanying the operator is that you'll get an appreciation of what your service levels should be.

Be realistic however; even if your pest management program does utilise periodic pesticide use (and most institutions do need it), it is impossible to completely eradicate and exclude these pests. It is essential therefore that you know your building and that you help target all such pesticide use since the ineffective use of these poisons is a danger as well as a waste.

The application of the pesticide is not the end of the story. It is also very important to record as many details of the treatment as possible, including the following (adapted from J. Dawson, CCI, no date);

  • the pest being treated for,
  • the pesticide, its trade name and manufacturer (MSDS),
  • stock and mixture concentrations and the solvent used,
  • the application method and follow-up procedures,
  • who carried out the operation and when,
  • the prevailing environmental conditions if relevant,
  • where it was applied,
  • monitor for any effects on collection material,
  • monitor for any health problems possibly attributable to the pesticide application (required under OH&S legislation).

The Cycle Begins Anew...

At this point the success of the treatment is evaluated. The approach to a pest threat, like any risk management strategy, is basically a cyclic one. After an inspection reveals a problem and a mitigation strategy is put in place (cultural change, physical modification or treatment), the results are evaluated by careful follow up inspections. New mitigation strategies must be implemented if the problem's not solved. Many organisations under-estimate the level of resourcing necessary to maintain this kind of vigilance however it only requires one infestation to show the very real costs of ignoring such risk management strategies.


Bernard Kertesz is Senior Paper Conservator at the Australian War Memorial and a long time member of DISACT. He has a biological sciences degree and long experience administering a pest management program. This is a brief introduction to the issues involved in setting up such a program. If you've any enquiries regarding pest management the author can be contacted at

Updated 12 August, 2005 , webmaster, CPBR (