Integrated Pest Management (IPM) for paper archives

What is IPM?

Integrated Pest Management (IPM) is a long-term management strategy to provide practical, safe, cost-effective and sustainable methods to prevent collections from being damaged by pests.

Principles of IPM

The principles of IPM are prevention, monitoring and control.

Prevention. Keep pests out and make the environment unsuitable for pests.

Monitoring. Recognise the pests and the damage they cause and assess by inspection and trapping.

Control. By improving the environment and by evaluating and implementing control methods.

You should:

Document any action taken. Monitor, evaluate and document the results.
Evaluate your IPM strategy regularly and update your strategy to improve it as necessary.

It is more effective and less expensive to prevent pests from becoming established than it is to treat a collection for pest infestation

Pests in paper collections

Pests in paper archives can be insects, rodents, birds or other animals that may cause damage to your collections.

Rodents cause damage by gnawing and chewing, as well as with their urine and droppings; which have associated health hazards. Birds pose a risk to collections due to their droppings. However, rodents and birds increase the risk of insect problems. Bird nests attract insect pests. The bodies of rodents and birds provide food for insects, attracting insect pests into your archives. In a paper based archive, insects are likely to pose the greatest threat.

When you look through your archive you may find evidence of historic rodent damage, and it is probable that you will find evidence of insect activity and damage to your collections such as holes, grazing of the surface, remains of insects and frass.[1] Much of the insect damage may be historic, however it is important to have a knowledge of pests to spot, deal with and prevent further damage to your archive.

IMAGES - Examples of damage

Image shows a manuscript where the bottom edge has been eaten away. *‘rodent damage’. Image courtesy of West Yorkshire Archive Service*

What pests need to thrive

It is not often possible to completely exclude pests from an archive and therefore it is important you create an environment which is unsuitable for pests if they do get in. By preventing the conditions that pests need to thrive you can stop them from becoming established and thus from damaging your collections. To thrive pests need food, shelter and a suitable temperature and relative humidity.

Food

Different insect pests have different requirements for food. In other words, some will be attracted to the adhesives, whilst others are attracted to the textiles or wood.

The food needed comes from several sources in your archives. One source is the archival material itself. Some examples are:

Adhesives such as gelatine and starch
Animal glue used in bindings
Parchment bindings on books
Wooden boards in books
Textiles used in bindings or found as inclusions in archives

Another source is the storage furniture such as wooden shelves, cabinets and cardboard boxes. These can all provide food for pests.

Other sources of food are found in your archive building including office areas, staff welfare areas, public spaces where food is stored and consumed, and areas where education activities take place. (Handling collections as well as the materials for craft activities can provide food for pests). One archive suffered an infestation of biscuit beetle due to an outbreak which originated in the toaster in their staff kitchen!

Shelter

This is sometimes referred to as harbourage. Shelter can be found in areas that are undisturbed for periods of time, making archive stores an ideal breeding spot.

The most common sources of insect problems are:

Old bird, wasp and bee nests in attics
Blocked chimneys and fireplaces
Old heating and ventilation ducts
Cavity walls and floors
Unused rooms or cupboards particularly in attics and basements.
Gaps between walls and floors
Dead spaces behind and under storage cabinets, display cases and plinths.
Dead spaces under and behind storage shelving
Woollen carpets

Environment

Different pests have differing needs for temperature and relative humidity. Some pests require the temperature to be above a certain level. Higher temperatures will increase the life cycle of insects. As a rule of thumb, warm temperatures of 20°C and above will encourage insect breeding. Some insect pests, such as biscuit beetle, will survive at low humidities. For biscuit beetle this is 40% relative humidity. Others, such as woodworm, booklice and silverfish, require a high relative humidity to survive, 60% and above. Archival material or collections that are damp are particularly susceptible to attack from some species. Additionally, when paper is damp it can support mould growth. Mould is eaten by some insect pests, causing damage to the paper surface at the same time.

In conditions of extremely high relative humidity, paper may be damaged by woodlice and snails.

What insect pests are eating your archives?

Common furniture beetle (Anobium punctatum). Woodworm. Generically known as a ‘bookworm’. Damage caused by larvae. Causes damage to wooden boards, paper, wooden storage furniture, plywood and card boxes. Does not thrive when relative humidity is below 55%. Only successfully completes its life cycle when wood is in an environment above 60% relative humidity.

Wood weevils (Euophryum confine and Pentarthrum huttoni). Causes damage to wooden boards and books. Needs high relative humidity to thrive.

Silverfish (Lepisma saccharina). Causes damage to the surface of paper and books. Feeds on starch, glue, ink and microscopic mould. Only breeds rapidly and causes serious problems in conditions of above 70% relative humidity. The Grey silverfish (Ctenolepisma longicaudatum) is now present in the UK. It is able to survive and breed at a lower relative humidity.

Common booklice (Liposcelis bostrychophila). Causes damage to the surface of paper and books. Feeds on starch, paper and microscopic moulds. Thrives in conditions of high relative humidity. Population increases rapidly in temperatures over 25ºC.

Varied carpet beetle (Anthrenus verbasci), Guernsey Carpet Beetle (Anthrenus sarnicus) and Vodka Beetle (also referred to as the brown carpet beetle) (Attagenus smirnovi). Damage caused by larvae, often referred to as ‘woolly bears’. Causes damage to bindings, and materials such as wool, fur, feathers, silks and skins. Feeds on animal glue and other protein-rich material.

Leather beetles (Dermestes lardarius). Also known as hide beetle or larder beetle. Causes damage to bindings with animal glue.

Biscuit beetle (Stegobium paniceum). Also known as drug-store beetle. Damage caused by larvae. Causes damage to paper, books and starch-rich board.

Spider beetle (Ptinus tectus and Niptus hololeucus). Causes damage to wooden storage furniture, wooden boards and paper.

Fungus beetles and Plaster beetles. Causes damage to papers and books. Grazes on microscopic moulds.

Clothes moths. There are a number of species of moths that cause damage to textiles. The common or webbing clothes moth (Tineola bisselliella) and case-bearing clothes moth (Tinea pellionella) are two of the most important species. Damage caused by larvae. Causes damage to textiles. Occasionally will tunnel into leather book bindings. Are rarely a problem in archives.

Image shows a small brown moth with its wings closed. *‘Webbing clothes moth’. Image courtesy of West Yorkshire Archive Service*

Illustrated poster of insect pests in historic houses and museums

Monitoring insect pests

You should regularly inspect your collection, storage areas and the building for signs of recent and current pest activity. Signs of recent and current activity could be seeing live insects, finding shed skins, frass and faeces and damage to archival materials. Identifying where conditions are favourable for pests to thrive can act as a starting point for your monitoring.

Image shows the bottom of a row of old books, on the shelf around the bottom of the books is a chalky cream powder. *‘Insect Frass’. Image courtesy of National Library of Scotland*

Key locations to monitor are:

Storage areas
Under and behind shelves and other storage units
Food service areas
Mechanical and service rooms
Basements and attics
Windows and doors
Fireplaces

Insect pests should be monitored using insect traps. Sticky blunder traps should be used for silverfish, booklice, carpet beetles and other crawling insects. Make sure that you use the correct trap for the appropriate insect species. There’s no point in using a pheromone trap for cockroaches when it’s other insect pests that are the problem. Traps should be placed in a regular grid pattern against wall floor angles, preferably in corners, at access points such as doors, windows and chimneys and near collections you are concerned about. Pest traps should be checked regularly and changed when necessary.

Most sticky traps will remain effective for at least one year. Pheromone traps will have a shorter usable life. For example, AF lure traps are effective for eight weeks.
Minimum frequency of checking is quarterly, March, June, September and December. Traps in areas with vulnerable material should be checked monthly. In areas where infestation has previously occurred or where a potential infestation has been identified, traps should be checked every two weeks.

Record the details of visual inspections, from your insect traps and of non-pest insects. This will allow you to see changes over time, distribution of pests, change in spread and numbers, the effect of any control measures you put in place and enable you to identify further actions required.

Image shows a printed grid headed with the trap number and location. The top line of the grid lists different pests, the left hand column lists dates. The correlating boxes list number of type of pest found. *‘Insect pest trap record’ Image courtesy of National Library of Scotland*

Remember to inspect cupboards, cabinets and drawers because they may have hidden cracks and voids which allow insect access. You should also check wooden storage furniture, floorboards and storage containers made of board for signs of active insect infestation.

Dealing with insect pests

As ever, prevention is better than cure. You should set up an IPM programme based on the IPM principles of prevention, monitoring and control:

Create an environment that is inhospitable to pests by removing sources of food and shelter, and addressing temperature and relative humidity
Practise good housekeeping. Archival material and the rooms where they are used and stored should be kept clean. Dirt and debris which accumulate in archives provide a food source for pests. Your housekeeping should include the dead spaces and hard to access areas which pests love. Keep the staff kitchen, and other areas where food is consumed, clean.
Practise good maintenance and insect proofing. Birds' nests should be removed. Create barriers to the entry of pests such as sealing doors, windows and ventilation ducts.
Inspect your archive, storage areas and building for signs of current pest activity.
Use pest traps.
Quarantine new acquisitions. Check for pests before putting the archival material into your archive.

If you discover an infestation there are four steps to follow:

Isolate material
Treat materials (Those visibly infested and those that have come from infested areas)
Treat the room/building - clean infested area. If appropriate, use a targeted treatment with an approved insecticide.
Prevent re-infestation

The treatment of the infested material depends on the type of material and the extent of the infestation. Remedial treatment includes: