This is based on the recognition that merely containing populations is sufficient to prevent damage, and is also less expensive, more sustainable, and poses fewer risks to humans and the environment.
In the context of archives and museums, most of the task is to create conditions that are detrimental to the development of pest populations, to make access to endangered pieces as difficult as possible, and to resort to containment measures only when a population spreads.
In the context of archives and museums, a pest is any biological life form that accelerates the decay of an object worthy of protection - that is, not only animals (such as rodents, mites, insects, and birds), but also lichens, fungi, mold, and moss, insofar as it attacks the fabric of a monument, for example. In most cases, this involves destabilization of the affected object through feeding damage, but also contamination with feces and other metabolic products (which can create an acidic or alkaline environment) or - in the case of moss and other plants on monuments - decomposition of mortar.
Depending on the pest species, different materials are at risk. Some creatures - such as rodents, mites and many beetle species - have a very broad food spectrum, while others specialize in certain materials: Clothes moths mainly attack animal fibers, i.e., fur, felt, silk, and wool; woodworms create the characteristic holes in furniture and beams; paper moths spread through archives. Birds, lichens and plants are more relevant to architectural monuments because of their outdoor habitat.
Pest prevention - prevention
Prevention occurs primarily through two strategies: first, making it as difficult as possible for pests to gain access to the objects to be protected through mechanical barriers, and second, creating environmental conditions that prevent pests from surviving and reproducing.
Outdoors, nets and spikes are placed on monuments as protection against pigeon droppings to prevent birds from perching on ledges and ledges. In depots and archives, organic materials, such as textiles, paper, wood, etc. - especially if they are very valuable and susceptible to feeding damage - are stored in inaccessible places, such as in airtight containers.
Many pests fare worse in cool, dry environments than in warm, moist ones. The room temperature should therefore always be kept at around 18°C, and in magazines and warehouses possibly even cooler. Humidity can be kept at about 50% by appropriate air conditioning. An exception to this is the paper flea, an insect that thrives even better at this value and must therefore be kept in check by other measures.
Strict hygiene is also an effective measure, since dust and other dirt particles can serve as the first food source for the pests themselves or their prey.
Early pest detection - monitoring
At least twice a year, but ideally even more often, all premises in question should be thoroughly inspected, including all containers, storage furniture and especially spaces between them and adjacent walls/floors - sometimes microclimates develop there that do not match the conditions measured in the rest of the room, thus encouraging the development of nests and foci undetected. Signs of pest infestation may include feeding damage (such as the characteristic holes found in woodworm infestations), the presence of eggs, larvae, shed skins, hairs and adults, and in the case of mold, a corresponding odor and stains on objects. Sticky traps are suitable for regular recording of insect infestations, provided they are replaced at set intervals; rodents can be detected by live traps.
Once an infestation has been identified, the second step is to pinpoint the population so that targeted action can be taken.
Pest control - IPM
The use of poisons or similar should be avoided as far as possible in accordance with IPM. Infested individual items can be exposed to strong temperature changes (by freezing or brief heating) - this is possible not only for small objects such as display cases, but even for medium-sized buildings by temporary isolation using tarpaulins and the use of hot blowers. As far as possible, animals and their nests, and on monuments, plants including roots should be mechanically removed. Sometimes pests can be controlled by other, harmless animals: ichneumon wasp populations have proven effective against clothes moths, but do not cause any damage themselves. Only as a last measure is killing advised.
Control methods according to DIN 16790 Integrated Pest Management
Many pest control methods are listed in the European standard DIN 16790 "Conservation of cultural heritage - Integrated Pest Management (IPM) for the protection of cultural heritage". The alternative methods defined there are preferable to an application of chemical products.
In addition to principles and strategies of integrated pest management, the following points are defined there:
General characteristics, prevention, detection and diagnosis, and response and treatment.
- Photosynthetic organisms
- Other hazards
- Low temperature
- Elevated temperature
- Oxygen deprivation or altered/controlled atmospheres
- Biocidal products
- Other treatments