Integrated pest management

Insect damage is fast, local and irreversible, and it is the risk most likely to be discovered too late in a collection that monitors climate diligently. A webbing clothes moth population in an unopened textile store can do more damage in one summer than fifty years of imperfect humidity.

The countermeasure is not a product, it is a cycle: monitor continuously, identify what you catch, act on the finding, then check that the action worked. Integrated pest management is that cycle, and the reason it is described as integrated is that the main lever is not treatment but housekeeping and building fabric.

Monitor

Blunder traps, sometimes called sticky or delta traps, are the backbone. They catch crawling insects that walk into them, they cost very little, and a numbered grid of them across a building turns a vague worry into a map. Pheromone traps target a specific species and are far more sensitive for that species, which makes them the right choice for confirming clothes moth or for tracking a known problem, but a poor general survey tool.

What matters more than trap choice is discipline: fixed positions, fixed check interval, and a record of counts over time rather than a note that says “some insects”. A single beetle means little. Six in one corner in June, when the same trap caught nothing in March, means a great deal. Insect monitoring traps covers placement and recording.

Identify

The count is only interpretable once you know what you caught, because the species tells you whether you have a collection problem or a building problem.

The main groups in European collections are the fabric pests, chiefly the webbing clothes moth and the carpet beetles, which attack wool, silk, fur, feather and skin; the wood borers, chiefly the common furniture beetle, whose flight holes are the visible symptom of larvae that have been inside for years; the paper and starch feeders such as silverfish and booklice, which are strongly associated with damp; and the general scavengers such as spider beetles, which live on debris and dead insects and tell you the housekeeping needs attention.

Silverfish and booklice are worth singling out because they are as much a humidity signal as a pest finding. A rising silverfish count in a store is often the first sign that the space has gone damp, and the useful response is a hygrometer as much as a trap. Identifying museum pests covers what to look for.

Prevent

This is where most of the benefit is, and none of it involves buying a treatment.

• Quarantine everything incoming. New acquisitions, loans and returns get inspected and, where warranted, treated before they enter a store.
• Deny food and shelter. Dust, dead insects, birds’ nests in roof voids, and stored food anywhere near collections are what sustain a population between meals of your textiles.
• Close the routes. Door brushes, sealed service penetrations, insect screens on opening windows.
• Prefer sealed enclosures. A boxed textile in a closed container is far less exposed than one on an open shelf.
• Keep it cool and dry where the collection allows. Most collection pests breed slowly or not at all below roughly 15 °C, and the damp-associated species need humidity to persist.

Treat

When something is infested, treatment is about killing every life stage including eggs, and doing it without leaving residues on the object.

Freezing is the workhorse for textiles, furs, herbaria and most organic material that tolerates it. It needs a low enough temperature reached fast enough, an adequate hold time, and correct bagging so that condensation forms on the plastic rather than the object.

Anoxic treatment holds the object in an atmosphere with almost no oxygen for several weeks. It is slower and needs more equipment, but it suits material that cannot be frozen, including some composite objects, painted surfaces and certain plastics.

Heat treatment under controlled humidity is used in some institutions and is fast, but the margin for error with mixed-material objects is smaller.

After any treatment, the object goes back into a clean, sealed enclosure and the traps around it get watched closely. Treatment kills what is present; it does nothing about the source, and if the source is a bird’s nest in the roof the problem returns next season.