Is pest control treatment effective?

IPM - Integrated Pest Control in Museums and Archives

Text by Astrid Hammer, Vienna (2012)

6.0 treatment

6.1 General

It wasn't long ago that pesticide use in pest control was common in museums. Many of the products recommended so far are no longer permitted because of their highly harmful effects, e.g. carbon disulfide (carbon disulfide), DDT or dieldrin (banned since the late 1970s). As research has shown, various pesticides also have a damaging effect on materials, e.g. dichlorvos. As a result, alternative treatments have been developed or are still being developed.

They are targeted gentle treatments that are only used when necessary (Pinniger, D. (1998): Controlling Insect Pestes: Alternatives to pesticides, Conserve O Gram 3/8, US National Park Service: http: // www.

After preparatory measures (see chapter 5.5 First steps in case of infestation) have been taken, such as isolation and packaging of all infested materials (, intensive vacuuming in infested areas, Disinfection and identification of the pests, advice is given on the appropriate treatment.


6.2 temperature

Very low or very high temperatures kill all stages of the insect, i.e. egg, larva, pupa and the adult. Temperatures below -25 ° C for 3 or more days, or temperatures above 55 ° C for one or more hours are usually effective. It is important to keep the objects in a micro-environment to ensure a stable relative humidity. This is done using closed PE bags or the Thermo-Lignum process. After treatment, the objects must be left in their controlled environment until they reach ambient temperatures again.


6.2.1 Cold / Freezing

The freezing of collection items has been one of the widely used methods since the 1970s, e.g. to free objects from natural history collections or textiles from pests. For a long time it was assumed that many objects should not be exposed to these low temperatures, as this can damage the material. This particularly includes glass, metal, glue, paints, sensitive (oil, acrylic on canvas, painted, varnished wood) or very old objects. In the meantime it has been shown that most objects and materials survive this treatment without damage and are therefore safer than assumed (e.g. Carrlee 2003, see 'Links'). In addition, it is an easy-to-use method, is quick to achieve success, requires little staff and is relatively inexpensive.


  • Fast freezing should be ensured within 4 hours (possible at -29 ° C) so that the insects do not acclimate to the low temperature. Allow good air circulation around the object!
  • Carefully pack in a polyethylene film / bag to avoid damage caused by fluctuations in humidity and condensation, possibly include absorbent material.
  • Duration: 3 days at -30 ° C (strand 2008, see 'Links'), 2 weeks at -20 ° C (if only one household freezer is available). Repeated freezing and thawing is not necessary!
  • Thawing in the packaging and acclimatization: 24h
  • Very good and up-to-date overview: Low Temperature Treatment (2012) - the latest findings, methods, devices, literature etc.
  • Very good video on the subject: Thompson-Webb, J. (2010): Expert Series: Pest Removal by Freezing or
  • Strang, T. (2008): Controlling Insect Pests with Low Temperature, Canadian Conservation Institute Note 3/3
  • Carrlee, E. (2003): Does Low-Temperature Pest Management Cause Damage? JAIC 42, 141-166 or low-temperature-pest-management-cause-damage /
  • Freezing methods on large objects in large numbers: Harris, K. (2011): Freezing matresses, ICON News 36, 18-20

Cold is also used preventively - to slow down the activity of the pests and thus prevent infestation: Low temperature storage of films using Vindons 5 ° C 35% RH heritage suit to avoid mold infestation (see chapters 3.2.3 and 3.2.4. Climate management).


6.2.2 Heat (heat, hot and warm air treatment) Brief description

  • A heat treatment at 55 ° C for about one day will permanently dehydrate all insects in all stages (egg, larva, beetle) and destroy the protein molecules (the 55 ° C must reach the inside of the animal).
  • Small objects can be heated in the oven, larger objects require a commercial furnace.
  • The objects should be packed to ensure stable humidity and to minimize / prevent damage.
  • Suitable for objects that do not contain veneer, glue, wax or other heat-sensitive material.
  • Advantages: Inexpensive, easy to perform, effective process with low maintenance costs.
  • Disadvantages: High temperatures can damage veneers or melt glue. However, damage such as shrinkage or other deformations can be reduced if the humidity around the object is controlled (Strang 1996, see 'Literature' below). This is done in the Thermolignum process. Thermolignum®

Thermolignum® Warm Air = controlled supply of humidity-regulated warm air at 55 ° C.

During the treatment, the relative humidity is constantly regulated in relation to the temperature, i.e. if the room temperature rises slowly during the heating phase, the relative humidity is increased, if the temperature falls during the cooling, the humidity is reduced. In this way, the wood moisture of the object always remains constant at the respective temperature. Tensions in the object itself cannot arise; Veneers, mounted or gold-plated surfaces do not change.

With the help of a complex, electronically controlled control technology, the objects are treated in a climatic chamber under their respective optimal conditions. The humidity in the objects is measured at various points and used as the basis for the further process. Based on this data, the other factors relevant to the process are calculated and the process is programmed. Parameters such as room temperature, room humidity and core temperature are documented.

Types of Thermo Lignum Process:  
  • mobile: The chamber is brought to the site of the damage and the objects are treated directly in front of the building.
  • In situ: Non-transportable, permanently installed or very large art objects (such as antique choir stalls, built-in organs) are covered with insulating material on site; all sensors are brought in and the measured values ​​are checked.
  • Treatment of buildings: Modified hot air process, i.e. the introduction of 55 ° C warm, humidified air into the building while enveloping the building. Introduced climate sensors guarantee the most extensive control of temperature and humidity.



Another method:


  • Nold, U. (2006): Wood-destroying insects, including a humidity-regulated hot air process applied in the Westphalian Open-Air Museum Detmold
  • Pinniger, D. (1996): Insect control with the Thermo Lignum Treatment, Conservation News 59
  • Tscherne, F. (2009): Applicability of a humidity-controlled warm air treatment. Thermo Lignum process for pest control on historical art objects made of wood with colored or gold frames and jsp? s = pest control
  • Strang, T.J.K. (1996): The effect of thermal methods of pest control on museum collections, 3rd International Conference on Biodeterioration of Cultural Property, Bangkok, Thailand 1995.
  • Pinniger, D. (2003): Saving our treasures - controlling museum pests with temperature extremes, Journal of the Royal Society of Chemistry, 10-11


6.2.3 Solar thermal treatment

The use of solar radiation for pest control, developed in 1995 by Tom Strang (CCI), is of particular interest in areas with relatively high solar radiation and limited access to expensive equipment and technology.

To do this, objects are wrapped in cotton and black plastic bags. This prevents fluctuations in air humidity and the escape of moisture, increases internal temperatures and prevents UV and visible light. The object exposed to the sun reaches temperatures of approx. 60 ° C inside, which results in the death of all insects and their stages within a few hours.




6.2.4 Microwave treatment


Microwave treatment is controversial, but sometimes the only choice with built-in woods.

Microwaves can heat an object unevenly, resulting in partial overheating. In addition, undetected metallic objects such as staples can generate sparks and ignite the objects.

By heating the wood to 60 degrees between 300 MHz and 300 GHz for about quarter of an hour, the insects are completely killed

Fig. Left: Mobile microwave irradiation of the parquet beetle in the Bodemuseum. From:



6.3 Anaerobic processes

The object is enclosed in a gas-tight container, from which oxygen is removed and / or inert gases (humidified nitrogen, CO2 or noble gases e.g. argon) is replaced. It is considered safe to use for most materials and objects. Iron cyanide blue pigments (iron blue, Prussian blue), which bleach under anoxia and permanently enter into chemical reactions, are an exception.


6.3.1 Nitrogen gassing

The use of nitrogen (N.2) in a controlled atmosphere leads to the death of the insects within 2 to 6 weeks. This was shown by means of respiration measurements before and after the oxygen concentration was reduced to 0.1-0.3%. The deprivation of oxygen causes a disturbance in the glucose production of the insect and leads to weight loss and consequently the death of the insects and their stages. The effectiveness of the treatment depends on the temperature, the relative humidity, the duration of exposure and the type of insect (Child 2008 (see below 'Literature') and nitrogen gas). Higher temperatures reduce the treatment period, since the animals' breathing increases with increasing temperature and leads to a faster loss of fluid (Valentín 1993, see below 'Literature'). Two weeks are sufficient at 25 ° C, and longer treatment times are required at lower temperatures. Higher humidity lengthen the process. Argon, which is much more expensive, works 25 - 50% faster than nitrogen (Nieves 1993, see below 'Literature') and offers even greater safety in the treatment of pest infestation, since argon also kills fungal tissue, for example, while nitrogen enables the same fungus survive oxygen deprivation (Koestler et al. 2004, see below 'Literature').

Systems that use nitrogen and argon are usually flow-through systems consisting of a gas-tight chamber that is either a rigid (mason jar, showcase or stainless steel barrel with a glass lid) or foil container (aluminum composite foil, escal foil, foil tent). The gas flow first removes the oxygen and then maintains the low oxygen level.

Smaller scale anoxic treatments can be performed with gas impermeable bags and oxygen absorbing chemicals such as Ageless or RP-K. The oxygen deficiency can be checked with the "Ageless eye". A pink color indicates the anoxic state.


Methods / Companies:
  • Humidification device for humidifying the gas flow during nitrogen gassing
  • Automatic gas supply Oxymin
  • Altarion® NitrogenoGas and tent fumigation with Altarion®-Vikane® gas (purified acid-free sulfuryl difluoride)
  • Nitrogen gassing
  • Veloxy nitrogen generator and
  • ZerO 2 System Hanwell Instruments Ltd. Oxygen absorbers, Flexicube, Flexiart, Flexitube and ZerO 2 Alert containers to indicate the absence of oxygen.
  • ZerOx system from b Cat (Williamsen et al 2011, see below 'Literature'): creates an environment with low oxygen content and controlled air humidification / temperature, removal of oxygen by means of carbon filters, for depot, treatment in containers, Tent, polyethylene bags, showcases.
  • ISOLCELL nitrogen generators VSA Adox N 2, PSA and Isosep
  • Accelerated nitrogen gas supply one week in a gas-tight autoclave at 24-26 ° C, 55-65% humidity and 0.0% O2 in the vicinity, 0.1% O2 in the object. The excess supply of nitrogen, which is made available by the build-up of a 4 bar nitrogen atmosphere with 0% residual oxygen, triggers a lethal dehydration process and possibly hyperacidity in the animal in addition to anoxia.

(Supplement to
  • Bergh, J. E. et al. (2003): The effect of anoxic treatment on the larvae of six species of dermestids (Coleoptera), J Appl Ent 127, 317-321 .00751.x.pdf (here also further literature on treatments).
  • Child, R., Pinniger, D. (2008): Using Anoxia to Kill Insect Pests: Methodologies and Methods
  • Koestler, R. J., Tavzes, C. and Pohleven (2004): A new approach on the conservation of wooden heritage, International Research Group on Wood Preservation, 35th Annual Meeting, Ljubljana, Slovenia 2004, available through IRG Secretariat, Stockholm, Sweden.
  • Selwitz, C., Maekawa, S. (1998): Inert gases in the control of museum insect pests. Los Angeles: The Getty Conservation Institute
  • Maekawa, S., Elert, K. (2003): The Use of Oxygen-Free Environments in the Control of Museum Insect Pests. Los Angeles: The Getty Conservation Institute (good summary of all Anoxia methods for museum objects).
  • Nieves, V. (1993): Comparative analysis of insect control by nitrogen, argon and carbon dioxide in museum, archive and herbarium collections, International Biodeterioration & Biodegradation 32, 263-278.
  • Willemsen, E. et al (2011): Innovation in Low-O2 Technology: A Solution for Conservation, Protection and Treatment, Restaurator, 13-26.
  • Berzolla, A., Reguzzi, M.C., Chiappini, E. (2011): Controlled atmospheres against insect pests in museums: a review and some considerations, J. Ent. Acarol. Res. 43, 197-204.
  • Valentin, N. (1993): Comparative analysis of insect control by nitrogen, argon and carbon dioxide in museum, archive and herbarium collections, Int. Biodeterioration and Biodegradation 32, 263-78.


6.3.2 CO2

Carbon dioxide (CO2) replaced by oxygen. The duration of treatment is approx. Four weeks with 8.2% - 4.8% oxygen, 60% CO2 and a temperature of 20-29 ° C. Newer methods show that the treatment times can be reduced if the CO2-Concentration is 80%. Then another 14 days are necessary. During this time, the CO2 do not fall below 60% and the temperature does not fall below 27 ° C. One advantage over the use of nitrogen or noble gases is that a CO2 Treatment requires less tightness of the chamber.

A disadvantage is the potential formation of carbonic acid with higher CO2Concentrations. This leads to damage to sensitive surfaces and pigments. However, the probability is low, as carbon dioxide only forms in water and not in moist air.

Further disadvantages are the long duration of treatment and complex safety measures to protect against escaping CO2which leads to suffocation.




  • Brand, S.J., Wudtke, A. (1997): Combating textile pests with carbon dioxide, depot in the German Historical Museum, Restauro 4
  • Warren, S.(2001): Carbon Dioxide Fumigation: Practical Case Study of a Long-Running Successful Pest Management Program, 95-101 in Integrated Pest Management for Collections, ed. Kingsley, H. et al., London: James & James


6.4 Use of natural enemies

6.4.1 Parasitic ichneumon wasps

The use of parasitic wasps for pest control has great potential. Parasitic wasps have been used in mills and storage rooms in the food industry for a number of years. Parasitic wasps are host specific, meaning they lay their eggs on the larvae and eggs of a particular insect.

Use in the museum area is still in the test phase. At the Pest Odyssey Conference 2011, Dr. Pascal Querner and Stephan Biebl results from 5 different museums in Germany and Austria, where parasitic wasps (Lariophagus distinguendus against the bread beetle Stegobium paniceum and Trichogramma evanescens against the clothes moth Tineola bisselliella) 1. for acute pest infestation and 2. for bowing.

The method seems to be promising, is inexpensive and can be used quickly and also as a preventive measure. The ichneumon wasp Lariophagus distinguendus was very efficient at combating beetles. Trichogramma evanescens proved to be less successful against the clothes moth, however regular use of wasps can minimize the moth population for years.

Further research is in progress, e.g. to determine the necessary distance between wasps and insects, the necessary number of wasps and treatment times per year.


  • Querner, P., Biebl, S. (2011): Using parasitoid wasps in Integrated Pest Management (IPM) against beetle and moth infestation, a critical evaluation, Conference Poster Pest Odyssey London 2011 .php
  • Querner, P., Biebl, S. (2011): Using parasitoid wasps in Integrated Pest Management in museums against biscuit beetle (Stegobium paniceum) and webbing clothes moth (Tineola bisselliella), J. Ent. Acarol. Res. Ser. II, 43 (2), 169-175
  • Biebl, S. (2009): Deutsches Museum: Beneficials against clothes moths, DpS 3
  • Mayhew, P., Heitmans (2000): Life history correlates and reproductive biology of Laelius pedatus (Hymenoptera: Bethylidae) in The Nederlands, Eur. J. Entomol. 97, 313–322 Parasitic wasps eat Trogoderma


6.4.2 Blue fur beetle Korynetes caeruleus (English Steely Blue Beetle)

This bright blue beetle is the natural enemy of the common rodent beetle / woodworm and the pied rodent beetle / dead clock. It imitates the larvae of the beetles in their feeding passages and eats them, pushing the drill dust out of the clogged feeding passages and creating the typical piles like the woodworm. After reaching adulthood, it lays eggs and dies. It is not able to destroy wood and could therefore be used to decimate the beetles mentioned.

Investigations into the use of the beetle in natural insect control are ongoing, see: Ott, R. (2007): Spurensuche - Investigations into the formation of dust piles in loopholes of the common rodent beetle, monument preservation in Baden-Wuerttemberg, Nachrichtenblatt der Landesdenkmalpflege 3, 164-167 http : // or



6.5 Pheromone trap Exosex

The Exosex system (moth confusion technique) has been on the market since 2007. English Heritage reported at Pest Odyssey 2011 on the use against infestation by clothes moths in an English manor house ( 20Lauder.pdf).

For more information, see Chapter 5.4.2 Monitoring - Traps and


6.6 Paper cleaning plant for removing mold



6.7 Traditional methods

Traditional methods are used when none of the above methods are applicable, e.g. for objects whose cultural origin, including spirituality, should be given special consideration, e.g. the Indian tribes of North America, Inuit or Buddha statues etc.

The methods in this case are:
  • isolation
  • Thorough control
  • Vacuuming
  • Monitoring

Back to tradition and monitoring:


6.8 pesticides

The use of pesticides is seen as the last option or weakest link in the IPM. Their use requires precise analysis and the greatest possible care. Professionals should advise and act with a high level of awareness.

Fumigations with pesticides are problematic because they represent a hazard potential for employees and the environment, are complex to carry out, e.g. due to the necessary exact sealing, the treated objects can outgas for a very long time, residues are left behind and there is no long-term effect. If carried out correctly, however, the application leads to 100% success.

Examples of pesticides:
  • Para-dichlorobenzene, a by-product of the production of the solvent monochlorobenzene, is harmful to health (liver, kidneys, lungs - carcinogenic effects) and accumulates in air and water.
  • Naphthalene, made from petroleum products, has little insecticidal activity and can loosen fats from objects. It is harmful to health (skin irritation, possibly kidney and liver, level 2 carcinogenic).
  • Camphor / camphor, made from essential oils of (among others) Lauraceae, is highly volatile. It has an EU approval for use against mites in beehives. It is irritating to the eyes and the respiratory tract. According to the recommendation of the MAK Commission, 13 mg / m3 used.
No longer in use:
    • Arsenic compounds (skins)
    • Mercury (II) chloride (herbaria, anatomical specimens)
    • Hydrogen cyanide (hydrogen cyanide)
    • organochlorine pesticides (e.g. DDT, lindane)
    • Methyl bromide (banned as a fumigant in Germany since 2006)
    • Dichlorvos / Vapona

Pyrethrum / pyrethroids - flower extracts from chrysanthemum species (Tanacetum) - act as a neurotoxic contact poison. Pyrethrum disintegrates quickly under UV exposure and has a short duration of action (approx. 20 min), pyrethroids are more stable. The carrier substance (e.g. rapeseed oil) leaves residues. The toxicity for warm-blooded animals is low. According to the MAK, 5mg / m3 can be used as an aerosol.

In the UK, Constrain ( is used as a mild insecticide to control all insects in museums, archives, historic buildings. It is made on a water basis, pH neutral, colorless and odorless and approved for use even by non-experts (Pesticides Regulations 1986). The active ingredient is permethrin. In terms of effectiveness, it is comparable to permethrin or bendiocarb powders as well as encapsulated chlorpyriphos (Pinniger et al 1994 and Morgan et al 1993, see below 'Links / Literature'). Examined materials such as textiles, paper, wood and metals showed no recognizable damage, changes in color, texture or sensitivity to corrosion. However, it is advisable to test with a very small amount before use.


Links / Literature:
  • - Solutions - Pesticide Treatment
  • Giere, P. (2008): Collection pests, Power Point presentation, 10th meeting of the curators' group at the Systematics 2008 conference Sammlungsschaedlinge.ppt
  • Pinniger, D.B., Morgan, C., Child, R.E. and Lankford, W. (1994): A novel micoremulsion formulation for the vontrol of museum insect pests. Proc IIC Ottawa Congress, Ottawa 1994.
  • Morgan, C., Pinniger, D.B., and Bowden, N.S. (1993): The effectiveness of residual insecticides against the carpet beetle Anthrenus and the implications for the varied control of the species. Proc 1st International Conference Insect Pests in the Urban Environment, Cambridge UK 1993.


Next chapter: 7.0 Introduction or implementation of the IPM and case studies

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