As you wander around the College you may see pest traps tucked into corners or placed high out of reach. These are part of a pest monitoring programme that I have been developing for several years and they play an important role in the preventative conservation that happens at the College.
What is preventative conservation?
Preventative conservation is about slowing down damage to objects. Certain pests can damage historical objects, mostly by eating or burrowing through them, so it’s important to make sure their numbers are controlled. Of course, pests don’t just damage objects. They can also be an indicator of environmental issues that could affect the collections as a whole.
Pest monitoring at Eton College
The two main traps I use are blunder traps and moth pheromone traps.
Blunder traps aren’t aimed at any specific pest, they trap anything that “blunders” on to them so that the general pest activity in that space can be monitored. These are normally placed on the ground, and you’ll find them in corners and along room edges.
Moth pheromone traps emit a pheromone that lures in male clothes moths. They help give an impression of how many moths there are likely to be in an area. These traps are usually placed off the ground, on windowsills or ledges.
Every three months, I collect and analyse the traps. The moth traps are relatively easy to assess, the more moths there are the bigger the problem. With the blunder traps, analysis can take a bit longer. There are many types of insect and not all of them are a threat to collections.
There are lots of pests that have been identified as a threat to collections and/or indicators of environmental issues. There are over 50 types of beetle and 7 types of moth that I need to be aware of.
At the College, the most predominant species of moth is the Common Clothes Moth. The adult moths don’t actually cause any damage, it’s their larvae that feed on animal protein like wool, fur and feathers and so are a big threat to carpets, natural history specimens and woolly jumpers.
The most common “museum pest” that we have at the College are Varied Carpet Beetle. Like moths, the larvae (also known as “woolly bears”) feed on animal protein and will often be found around natural history specimens. They are also a common household pest so you may find them around your homes.
The College also occasionally gets bigger pests, like the mice that were found in one of the Libraries a couple of years ago.
How to deal with them
The first thing I do is thoroughly check the area around a trap and try to identify the source of the problem. Have the pests come in through a gap in a window or even down the fireplace? Is there something new in the room that they could have come in on? Treating the space is just as important as treating the object.
For the objects, there are several ways to tackle pest issues including high temperatures; carbon dioxide and anoxia (low oxygen). The method used at the College though is freezing. We have two freezers on site specifically for treating objects with pest issues, so I wrap the items and then freeze them for 2-3 weeks. This is usually long enough to kill the adults, larvae and eggs. Afterwards, they are cleaned with a museum vacuum (a small vacuum that has variable suction) and put back.
As for the mice, I use humane traps to catch them, luring them in with shortbread and walnut, and then release them away from the College. None of them have returned to the collections…yet!
By Sara Spillett, Conservation Housekeeper