Response Methods to Eliminate Pests

Response methods

Sanitation to reduce pest populations.

Action

Aggressive application of Avoid and Block stages. Physical removal of pests and frass, by picking or brushing by hand, or by vacuuming. Sweeping and mopping are less effective than vacuuming to remove most pests.

Response methods

Subdivide for protection, quarantine, and treatment.

Action

Seal objects in containers or bags to subdivide problems into manageable units for treatment.

Response methods

Dehumidify to remove hazard.

Action

Mould growth occurs only in conditions above 65% RH (or equivalent moisture contentsfor each material). Changing ventilation patterns or adding effective refrigerant or absorbent dehumidification systems to reduce high humidity throughout the year will reduce mould damage. For example, consult Case Study 2.

Response methods

Dehumidify to reduce viability.

Action

Damp-loving insects (e.g. silverfish, psocids, lathrids) require elevated humidity for at least part of their life cycle. Eliminating damp in walls, basements, attics, and service rooms year-round will reduce the numbers of these insects.

Response methods

Cutting off or restricting ground water.

Action

Water that is taken up into organic structures accelerates fungal attack. Using dampproof layers, including materials to drain water away from site, and elevating structures to break absorbent contact with soil are three strategies that slow fungal attack.

Response methods

Cool to exterminate or control.

Action

Place affected object in a polyethylene bag or equivalent vapour-barrier container and hold (most conservatively) at −30 to −20°C for 1-2 weeks. −20°C for 1 week kills most insect pests infesting museums (Strang 1992). Lower than −40°C for insect pest control is not necessary and begins to risk thermal stresses on temperature-vulnerable composite objects (e.g. mixed metal-wood veneer). Permanent storage in cold rooms, at less than 10°C, will minimize insect damage risk, but elevate moisture risk and catastrophic mould risk if moisture is not controlled by bagging, mechanical systems, or prompt intervention if the system fails. There are very few objects in general collections that cannot be exposed to this cooling method. Consult Case Study 3.

Response methods

Heat to exterminate.

Action

Heat an object at 55°C for 1 to several hours. Exposure is calculated on maximum thickness of the object component or determined by direct measurement of the object. Consult Strang (1995, 2001) for detailed guidance on issues surrounding heat disinfestation. Enclose the object in a water-resistant bag to prevent desiccation. A wide variety of objects can be safely heat treated. Solar heat can also be harnessed for this purpose (Strang 1995, 2001). Consult the "Thermal control application guides" section. Commercial heating processes balance moisture in the treatment chamber so individual bagging is not required. Wood for export shipments such as pallets and crating is now heat treated to destroy timber pests and marked "HT" (Canadian Food Inspection Agency, ISPM 15). Consult Case Study 4.

Response methods

Fumigation to exterminate.

Action

Fumigate objects using carbon dioxide or nitrogen in approved plastic bubbles or fumigation chambers. Nitrogen fumigation by oxygen scavengers can be done in small bags, e.g. using Ageless with heat-sealable, oxygen-barrier plastic films (Maekawa and Elert 2003). Toxic gas fumigants are not desirable because of their environmental and health effects and chemical interaction with objects. Few toxic gas fumigants are available in Canada to use with museum objects or structural fumigation.

Response methods

Apply fungicide to exterminate.

Action

Wood attacked by fungi can be treated in situ with fungicides. Borates, one of the lowest toxicity systems, continue to penetrate after application, but are washed out by surface water. Other residual fungicides may be coloured, less penetrative, or have restricted use. Surface sterilants, such as dilute sodium hypochlorite bleach (0.5%) or 70% ethanol, can be used on hard surfaces in places that do not directly affect objects. Quaternary ammonium compounds in cleaning solutions can also kill microorganisms but may affect metals, so do not use them directly on objects. The effectiveness of biocidal cleaning solutions depends on contact time.

Response methods

Apply pesticide to exterminate.

Action

Pyrethroids (e.g. permethrin), carbamates (e.g. bendiocarb), etc. are generally applied as sprays of liquid chemical mixed with a diluting agent, now commonly wateremulsion-based formulations, but some solvent-based sprays exist. Baseboard, crack and crevice, and cavity sprays are advised. However, direct or incidental spraying of objects is highly discouraged, as it can cause staining as well as mechanical and chemical damage. Pesticides have a range of action speeds, but are not equally effective against all insect pests or life stages because of their differing abilities to be picked up and absorbed or ingested. Pesticides are registered for specific pests and cannot be used outside their defined purpose (Dawson 1992).

Response methods

Apply desiccant powders to exterminate.

Action

Silica and diatomaceous powders especially formulated for insect control can be blown into problem cavities and dusted under permanent exhibits to eliminate pest shelters. The particulate size is larger than those types of particulates that pose a severe chronic exposure hazard to human respiration; however, protective equipment is necessary when working with these powders. Some powders are co-formulated with "knock down" pesticides.

Response methods

Trapping to reduce a rodent population.

Action

Snap traps can be baited and attached to runways. They generally ensure that the rodent is killed quickly. Adhesive traps are efficient and do not suffer from trigger failure. There are some guidelines for humane use, particularly early removal of a rodent caught in a trap, and killing it if it is still alive to reduce its suffering. Repeat action trap cages can remove larger numbers of rodents in high-population densities than can single traps. Live traps will not ensure the rodent is removed permanently from the site because they may re-enter after being released in the open. Sealing the affected space is essential for effectively trapping rodents in order to remove them from a building or they will continue to enter from exterior sources.

Response methods

Rodent baits to exterminate.

Action

Toxic baits (e.g. warfarin) are delivered in bait stations to reduce inadvertent poisoning of pets and people. Toxic baits are not advised for use in collections for two reasons. Poisoned rodents may die in building cavities or in collections and attract very destructive insect pests. Rodents can carry poison baits and other items (e.g. glass fibre insulation) with their mouths in a manner that protects them from swallowing the materials. Rodents caching bait outside the bait station creates a potential poisoning hazard to humans. Bait stations are more commonly used outdoors around the periphery of buildings. Caution: rodenticide baits are dyed with warning colours (blue, red, green) commonly seen in food, particularly children's candy. Many rodent bait formulations also support insect pest life, so remove any bait after its utility decreases.

CCI Technical Bulletin Nº 29.