Have you ever opened your wardrobe to find your favourite winter jumper has been attacked by clothes moths and is ruined? This sort of problem isn’t just confined to the home and can be a headache for people working with museum collections too – and it’s not just clothes moths – there’s a whole army of ‘pests’ out there who’d like nothing better than to have a nibble at our precious collection!
Of course, out in the wild these ‘pests’ have a noble job to do – they make short work of dead branches, old bird’s nest and rotting rabbit skins – leaving nothing but dust and ‘frass’ (waste produced by the insect’s activity).
So who are the main culprits at the museum and what can we do about them? They can be divided into borers, shredders and grazers.
Borers are the larvae of insects such as furniture beetle and death watch beetle; rarely seen they leave clues of woody frass and distinctive holes. Death watch beetle prefer a damp hard wood with fungal decay and make larger holes, the adults ‘tick’ loudly in Spring for a mate. A water-based insecticidal timber treatment is brushed on wooden objects at risk when they enter the store – the treatment also has anti-fungal properties.
Shredders really can shred! Clothes moth and carpet beetle larvae ‘woolly bear’ love dark, warm environments and thrive on keratin-bearing materials – wool, fur, feathers. Woolly bears (hairy creatures whose skin moults as it grows) will eat and breed on non-pest insects too so it’s important to clear up dead cluster flies and spiders. Case-bearing clothes moth larvae are recognised by cigar-like cases whilst webbing clothes moth larvae secrete long silky tubes. Vigilance and regular cleaning are good deterrents before damage is done – and if they are found, gentle vacuuming, a conservation-grade, water-based, PH-neutral insecticide or a short-spell wrapped in the freezer usually does the job.
Lastly, there are grazers such as silverfish and booklice. These have a liking for refined cellulose (preferably damp) – paper, linen and cotton – and will ‘graze’ the surface area. Silverfish are known to like organic dyes and have stripped historic wallpapers following the pattern! Tiny booklice don’t have males and all lay eggs; under warm, humid conditions their population can explode. Sometimes museums find aids such as (bat-proof) sticky blunder-traps useful, especially for the monitoring of smaller suspects, but overall, vigilance, regular cleaning and good storage is key.
This month, the National Trust is set to begin a ground breaking new pest – control trial, to tackle clothes moths! Click here to read more about it.