Pest Management: a Perspective
Bernard Kertesz.
Introduction
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,
http://palimpsest.stanford.edu/bytopic/pest/
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.
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