Posted by Penelope Lovesy at 05/06/2020 17:58:20
Pests are a constant issue for museums and their collections, and I don’t mean the variety that run about and throw stink bombs. You yourselves at home will have undoubtedly had your fair share of run-ins with pests, but what you encounter at home may well be different to a museum’s public enemy number one. That creepy eight-legged freak crawling across the bathroom floor might terrify you but it’s not going to scare our costumes or natural history specimens. Over the last few weeks I have had issues in my dining room with ants not understanding the current social distancing regulations but I’d not expect to open the door of Poole Museum to find hoards of the blighters carrying away an antique piano (even if TV’s ‘Ben and Holly’ suggests otherwise!)
Due to the varying make up of museum collections, pests are a regular threat and keeping a constant watchful eye out is imperative for their survival; the collections that is and not the pests. Maintaining consistent environmental conditions goes a long way to keeping many insects at bay and is essential for object conservation anyway. Many museum objects are sensitive to humidity, light and temperature but sometimes the conditions required for good collections care could also provide a wonderful habitat. Afterall, what self-respecting furniture beetle wouldn’t want to hang out in a cool, darkened room with a nice dry mangle?
And it’s with those pesky kids, I mean furniture beetles, that we’ll begin our examination of a few of the most notorious museum pests.
I’m sure you’ve all seen wooden stuff with little holes in and it’s likely that Anobium punctatum, or furniture beetle / woodworm to his friends, was responsible. These little beetles are only about half a centimetre in size, but they can rapidly destroy entire wooden collections if left to their own devices. You know how it is, boy bug meets girl bug on date at the fly-through, they hook up and have up to 70 babies at a time and find the most luxurious two up two down piece of wood they can as the nursery. To be honest, I don’t blame them, they’ll only live for five years so why not have as much fun as they can while they can? Well, obviously, it’s because they wreck museum collections and our responsibility as a museum is to care and conserve our collective heritage for future generations…of people…not woodworm. By the time you see physical evidence of the problem it is likely nearing its close, at least for that particular object. Female beetles crawl their way into the natural cracks in the wood and lay anything between 30 and 70 eggs at a time. Those little holes you see are the end of the young’s occupancy of the wood; the end of up to five years of entirely consuming the internal structure of the object. After their lengthy stay, the larvae head to the surface to pupate, before gnawing their way out as fully-fledged beetles, leaving the circular exit wounds as the go. Dark empty holes are long since vacated but fresh holes look pale and full of powder. You’ll often see the powder building up on the floor or other fat surfaces under the holes or even the resultant frass (droppings). Once you encounter one fresh hole there are more to follow so that’s the time to act, before the guests drop their keys off and give you a 5-star rating for their stay.
Next up are a group of critters commonly referred to as Carpet Beetles, but believe me, they’re not that picky about eating other things as well. The most widely seen of the bunch is the Varied carpet beetle (Anthrenus verbasci). These aren’t particularly big either, being a similar size to furniture beetles, and, unsurprisingly, it’s the offspring that cause havoc. The larvae are covered in fine hairs, which gives rise to the nickname ‘woolly bears’. These larvae are less than a millimetre when they hatch meaning they can get in just about anywhere that isn’t sealed. As they grow, they continue to feed on wool, silk, skins, feathers and fur and shed their outgrown skins, called husks. It can take two years for the larvae to pupate and reach adulthood; just think of the damage they can inflict on the contents of your wardrobe in that time! The Varied carpet beetle, the Guernsey carpet beetle (Anthrenus sarnicus), the Varied carpet beetle’s slightly larger cousin, and Anthrenus fuscus (which must be the grumpy cousin as it doesn’t have a common name) are almost impossible to tell apart; their markings are almost identical and the larvae similar in appearance too. But let’s face it, a carpet beetle is a carpet beetle and we don’t want their kind visiting thank you very much! As you might expect, more distant cousins might also come along for the ride. The two-spot carpet beetle (Attagenus pellio) is easily identifiable by the two or more spots, and Brown carpet beetle (Attagenus smirnovi), or Vodka beetle, is plain and brown with their young both being less hairy but impossible to tell apart.
The list of beetles that want to eat collections is gargantuan and include some wonderfully named characters; Drugstore or Biscuit beetle (Stegobeum paniceum), Cigarette beetle (Lasioderma sericorne) and Golden Spider beetle (Niptus holeucus) to name but a few.
The images at the top of the page show a couple of dastardly fiends that decided to take advantage of Poole Museum’s free entry. On the left is a dead furniture beetle with frass and on the right two ‘woolly bear’ husks from the larvae of carpet beetles.
In the next exciting instalment of Pests in Museums we’ll examine the dreaded moths and the secretive booklice and silverfish. Until next time; stay alert, control the pests, save collections!