Julia & Angelika--You are probably already familiar with the use of
pheromone traps to monitor the size of an insect problem, but others may not
be. Insects Limited is a company that sells pheromone traps specific for
wool eating pests--and is very helpful in telling you where and how to
deploy them. Their website is www.insectslimited.com They just had a
conference & workshop in Copenhagen in June. Their  recent Newsletter,
"Fumigants & Pheromones" Issue #67 Spring 2003 has some very good
information on trap placement and species, as does the website (click
Museums). With suspicion of insect activity, these pheromone traps are an
excellent way to monitor a collection.
My sympathies to our European colleagues for the terrible hot weather--a
newspaper article pointed out recently that the higher temperature
accelerates the life cycle of insects. With more generations present, the
number of potential insects may be unusually high.