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17 Sept 2020

Pests in collections – silverfish

Written by Lesley Scott, ACR Conservation Advisor, Edinburgh & East
A close-up of a woman with white conservation gloves holding a hardback book with an orange cover.
Wendy Purvis, Operations Manager at Falkland Palace, examining books for silverfish damage
Awareness of the pests that can cause damage in historic properties and diligence in preventative practices aimed at controlling the impact of pests on collections is a vital part of how conservation teams care for and preserve objects and interiors.

The usual bustle of collections staff and volunteers carrying out their pest management programmes and regular housekeeping in properties wasn’t possible during lockdown. Unfortunately, this was when pests were at their most prevalent and there’s been a resurgence of tiny invaders previously kept in check through preventative practices. Coupled with some warm and wet weather raising temperatures and humidity levels, one of the oldest insects on the planet has been spotted within our collections – silverfish.

Silverfish (Lepisma saccharina) are commonly found in homes worldwide, especially in more humid or damp areas, where they can be seen at night, scuttling across surfaces. These long-living insects derive their name from shiny metallic scales on their bodies and the way they move side to side, like a fish. They’re notoriously very difficult to get rid of and are able to live for a year without food as long as they have access to water.

The good news is that they don’t bite, predate on other insects or spread disease. But if left unchecked, they can damage your treasured pictures, furnishings and wallpapers, grazing through objects that contain starch or other sugars. They’re also partial to dandruff, glue, toothpaste, detritus and microscopic mould.

Close-up of the top of a book, with a small, silver insect crawling on it.
Silverfish are a species of insect older than the dinosaurs! Common in homes as well as historic properties, they can damage collections by grazing on starches and glues if undetected

Speedy little critters, they can run faster horizontally as opposed to vertically, being equipped with six legs to get away from predators such as spiders. If you do see one and think they resemble something prehistoric, then you’d be right as there were silverfish around some 100 million years before dinosaurs.

Close-up of the head of a silverfish insect, showing its front two legs and antennae.
Silverfish have six legs, a tapered, segmented body with long antennae and three long bristles on their back end. They are thought to be the one of the oldest and most primitive insects alive.

In historic houses they enjoy eating the organic ink on historic labels, scraping letters away as they graze, making the text illegible and causing loss of vital information. As with most unwanted pests in historic properties, they thrive in isolated, dark, infrequently used areas and are not always obvious until the damage has occurred.

A page from a book showing pest damage by a silverfish.
Detail of historical damage from silverfish grazing on a book cover. Returning from lockdown, vigilant staff found evidence of past silverfish damage in books at Falkland Palace

Pest problems are not new and treatments have been undertaken since the 1700s, which have saved many historical objects. However, as some of the treatments included pesticides or the use of poisonous substances, which we now understand have risks to human health, modern approaches are geared towards preventative measures known as integrated pest management programmes (IPM).

IPM was first used in the food industry in the 1950s to prevent the overuse of pesticides. These principles were adopted and introduced into museums in the 1980s and we use them today throughout all Trust properties.

The use of chemical treatments to eradicate pests is limited to when it’s absolutely necessary. The advantages of an IPM systematic approach to monitoring and targeting treatment is that it’s minimally invasive for our collections, as well as being better for the health and safety of people and the environment. Once established, it’s also cost-effective and sustainable.

A small triangular museum trap used for monitoring insects
A blunder trap used to determine evidence of pests in historic properties. We monitor numbers by using traps to catch those insects that blunder into them

Silverfish will always be present in our properties, but we have learned to live with them in a controlled and monitored way by having housekeeping regimes including dusting, checking and maintaining environments that suit the collection’s care rather than the insects. So if you visit our properties and see someone with a torch, dusting, or strange little triangular traps under furniture, you know that the battle to preserve Scotland’s heritage is ongoing.

Close-up of a bookcase being dusted with a paintbrush.
Silverfish are nocturnal, so regular cleaning disturbs these hard-to-spot insects

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