Bill Landsberger is what one might call the modern version of the Staatliche Museen zu Berlin's ratcatcher. His job is much more complicated than that, however, and he has his sights on much smaller pests than rats, for the entomologist based at the Rathgen Forschungslabor (or research laboratory) is currently working on a ground-breaking pest prevention programme for all the museum collections. In the following interview, Landsberger explains what the programme involves and reveals why human beings often become unwitting accomplices for the insects.
Mr. Landsberger, what exactly does your job entail?
Well, as an entomologist at the Rathgen Forschungslabor I head up a programme against pest infestations, applicable to all institutions under the Stiftung Preussischer Kulturbesitz. It's known as Integrated Pest Management, or IPM. It involves the prevention, comprehensive systematic monitoring, identification, and finally also the elimination of pests in the event of an infestation.
What are the most common pests in museums?
A lot of them are the same one may already know in the home. The 'usual suspects' are clothes moths (which can also live off furs), common furniture beetles, woodworm, fur or carpet beetles, and biscuit beetles. Other collection pests are silverfish because they digest the cellulose in paper and thus present a threat to archives and libraries. And, in addition to insects, mammals such as mice and rats can also be harmful to museum collections.
What sort of damages can be incurred in an infestation?
Well that depends very much on the type of pest. Most often the result is of course material loss, when the animals eat wood, paper, or textile fibres. I've even known one instance in which mice built nests out of object labels. The worst-case scenario in such an eventuality is staff no longer being able to match the labels to their relevant objects, meaning that essential information relating to the objects gets lost. An infestation therefore doesn't always mean the total loss of the object, but it does cause an enormous amount of work and restoration costs. These costs make investing in an effective Integrated Pest Management worthwhile.
Are pest infestations a regular occurrence in museums?
I'm afraid they do happen from time to time and are hardly avoidable. One example would be the Ethnologisches Museum. There was an accession in 1983 of a wooden boat from the South Pacific. It entered the storerooms straight from the ocean, so to speak. Back then no one noticed the stowaways on board: a colony of drywood termites. Well, they certainly made their presence felt in 2011…
The termites spread over the storerooms and settled in other wooden objects. For example, a Venetian gondola, which was unfortunately placed close-by. That's precisely the kind of emergency our preventative system aims to avoid. Therein lies the ambivalent nature of my work: if everything goes well, then there are no problems and my job goes unnoticed. But if something goes wrong, then my job becomes a concern.
How do you react when an infestation is detected?
First I have to find out what kind of pest it is. In my lab I have a collection of live animals, specimens, and feeding marks that I can refer to for comparison. Once the culprits have been identified, I can decide what type of treatment is best. On principle, we avoid using control agents, because there are always alternatives. We routinely rely on two methods of treatment: oxygen deprivation with nitrogen and freezing the objects at -30°C. Ultimately, the conservators decide which treatment should be performed, whether the object can take it or not.
How do you monitor the collections?
We set up neutral adhesive traps in the storerooms. The insects run into the traps and get stuck there. In addition, there are traps that work with pheromones, like the ones for clothes moths. There are also traps that work with UV. Thanks to all these different types of trap we can always see which organisms are present in the collections' storerooms and which of those are potential pests. Basically it's an early warning system.
It sounds like there are pests lurking everywhere.
Exactly! I'm afraid we don't live in a sterile world, with all insects confined to the wild. The IPM plans for the more effective sealing off of weak points, such as windows and doors, to try and prevent pests entering in the first place. Take the Archäologisches Zentrum, for example. The doors to its storerooms are massive and several inches thick. They may be effective at keeping an elephant at bay, but there's nearly a whole centimetre between the door and the floor - no obstacle for insects. With a simple brush-strip draft excluder we were able to minimize the problem. But it's a good example of how architects and planners are still often unaware of the problem.
Are there any other ways that insects find their way into the museum?
The ever increasing number of loaned objects increases the risk of contamination. Which is why an integral aspect of the IPM is the routine treatment of new objects, be they loans or accessions. But there's another important factor I haven't mentioned - human beings.
You mean visitors and staff bring pests into the museum?
The insects enter by themselves, but people feed them by dropping food crumbs, woollen fibres, and other things that give the pests a reliable food source. Take the 'Gesichter der Renaissance' exhibition in the Bode-Museum, for example. It attracted huge crowds. There were so many people that additional cloakrooms had to be set up. Unfortunately, the coats were hung up directly above ventilation shafts and there was a steady stream of loose fibres that drifted down into areas that were seldom cleaned, because until then it hadn't been necessary. The result was a vast accumulation of lint and fibres - and a massive infestation of moths. Thanks to our monitoring processes we were able to detect them immediately and quickly got rid of them with a thorough cleaning.
Despite your programme, infestations do occur in museums every now and then. Behind the facade of every museum in Germany, is there a permanent battle raging, unseen by visitors?
In some other museums and collections, the battle is waged on a case-by-case basis, as before. If there's a problem, an exterminator is called who uses pesticides and then leaves again. That's one way of tackling the problem for the moment, but it's not sustainable. We're working towards a situation in which major infestations become extremely rare, but there's still a long way to go in implementing our programme. However, you will never be able to completely prevent pests entering the museum.
One last question: what is your 'favourite' pest?
I have spent many years working with termites. They fascinate me most of all due to their strong social structures, which are completely out of character for insects. Termites are my special friends.