Pest Monitoring to Protect Our Archive Collection

on Tuesday, 30 March 2021. Posted in Archives, Conservation, History Centre

Surprise! - Historic pest found in archive volume by an unsuspecting archivist

We’ve recently reviewed the Integrated Pest Management (IPM) programme that we have in place at the history centre so that we can effectively protect the archives from the possibility of any damaging insect pests.

IPM is a multi-faceted approach to pest management and our program is used alongside a number of other preventative measures such as good cleaning and housekeeping routines, thoroughly checking new accessions for any hitchhiking pests before they are put into the strong rooms and maintaining a stable environment within the strong rooms so that pests do not feel at home. This way we can continue to protect our archives into the future.

Insects can cause a real problem for historic collections, which can be tasty treats for them to feast on, causing irreversible damage and loss of information.

It is really important to protect the archives against possible pest infestations. A small number can quickly increase to become a big problem if left unchecked and cause substantial damage to a collection.

During the pandemic some collections such as The National Trust have reported increased pest activity due to the reduction in footfall and reduced monitoring and cleaning of spaces, leaving areas undisturbed for pests to thrive. With such large numbers of documents held in repositories such as WSHC it is impossible to frequently check all items individually, so programmes to monitor and reduce numbers are put in place.

We have set up ‘blunder traps’ in the History Centre, strategically located around the strong rooms and other areas of the building, and by frequently monitoring them we are able to get a picture of any pests present and which areas they are visiting.

The traps we use do not control pest infestations they simply allow us to monitor levels of pests. If we find a pattern of large numbers of any particular archive pest, we can then look into dealing with any problems and target them specifically.

Examples of historical pest damage found in our collection

Monitoring the Situation

We currently have 32 blunder traps around the building, these are placed near doors and vents; points where pests may enter the space, in areas where archive material is handled or stored.

A blunder trap in use in the archive lab
Checking each trap using stereomicroscopes

Before lockdown the IPM team checked the traps around the building as we would normally do on a quarterly basis. We collected all the traps before looking at each one under a stereomicroscope. Some of the insects and pests are so tiny they can barely be seen with the naked eye, so it is important to check each trap even if they look empty.

We have found all sorts of insects but not all are a threat to our archive collection such as spiders and ants. We keep a spreadsheet of all the insects we find that are considered to be archive pests known for consuming archive materials such as paper and leather. Commonly they will feed on things like cellulose, starches, and proteins found in collections hidden in adhesives in bindings, leather book covers and parchment documents to name but a few.

Common Archive Pests

Psocids commonly known as Booklice are a pest frequently found within archive materials. They feed on damp paper and books by scratching the surface and eventually leaving bare or translucent patches. They are difficult to see with the naked eye at less than 1mm in size and as they are so small it takes a large number to cause significant damage.

A Psocid found in some newly acquired documents

Silverfish (Lepisma Saccharina) are commonly found around the house but are an unwelcome guest in the archive. They are easy to spot due to their strange appearance and visible size usually between 10-15mm. They thrive in a damp environment, eat paper, books and textiles and also scrape the surface in the same way that Psocids do.

Varied Carpet Beetle (Anthrenus Verbasci) are quite distinctive despite their tiny size of 2-4 mm. They are round in shape with grey and gold scales. The adults do not cause damage themselves, but their larvae known as Woolly Bears will nibble away at archive documents.

Woolly Bears look as strange as they sound. They vary in size from 0.5mm-5mm and are short and fat with bands of hair and tufts at the head and tail. They will eat wool, fur, feathers and animal proteins leaving small neat holes.

A Woolly Bear

Dealing with a Situation Before it becomes a Disaster

One of the main concepts of an IPM programme is that we can identify a pest problem developing and deal with it before it becomes a disaster, causing irreparable damage to precious archive documents. Depending on the type of pest this may involve using more specialised traps such as pheromone traps that attract specific species, if possible, we will locate the source item that may have become infested. To treat an infestation we would package and remove items from the area of the infestation and place them in our conservation freezer if suitable (not all materials can be frozen) which has the required temperature level of -18˚C or below to kill the pests and halt their spread. It may in some situations be necessary to use chemical fumigants in situations where freezing is not suitable or has not worked.

Sophie Coles, Conservator (Archives)

For more information about Insect pests visit What's Eating Your Collection

The Conservation and Museums Advisory Service (CMAS) aims to promote excellence in the care and use of collections by providing conservation advice and practical treatments to heritage organisations and the public. It also supports museums in Wiltshire to meet professional standards and become sustainable.

If you would like conservation advice about your own documents or objects, please contact the team This email address is being protected from spambots. You need JavaScript enabled to view it.

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