What did biscuit beetles eat before humans invented the custard cream?

Our kitchen hygiene has improved of late. I have not seen a biscuit beetle, Stegobium paniceum, for over a decade. They are, methinks, a declining species in East Dulwich. I blame all the new grand kitchen extensions being built, with sliding glass doors, picture windows, flush-fitting cupboards, and Tupperware storage boxes.

Our previous house, over in Nunhead, had a very unfitted kitchen. We unfitted it ourselves. And in place of the crammed and cramped wall units and plastic work surface, we stuck in a salvaged (for which read ‘old’) chest of drawers for the plates and saucepans, and put some shelves into the old larder alcove to make…well, a larder. This was cutting-edge kitchen chic at the time, or so we thought.

It was after a week of finding the small beetles floating in the milk of my breakfast cereal that I decided to try and find the source of the Stegobium infestation. They  were in the porridge, the Shreddies and the Rice Crispies, in the sugar, flour, lentils, rice and paprika; they had bored holes into the spilled cat biscuits knocked under the boiler; they had chewed through the tin foil of the Oxo cubes. And they had turned my medium egg noodles into ticker-tape. Of course, I thought this was fascinating. But I did agree it was a bit much to be sharing the kitchen with so much wildlife — we had a clear out.

My noodles have been ticker-taped by biscuit beetles. You can just see the behind end of one, bottom left.

Although in Britain this is the ‘biscuit’ beetle, a sign of our predilection for a little something to dunk in our tea, elsewhere in the world it is usually the ‘drugstore’ beetle. I’m guessing that this is because it feeds on the milk or starch powder that makes up most of the aspirin tablet, rather than an addiction to pharmaceutical products.

I recently got to thinking about where these cosmopolitan beetle pests might have lived, before they became so attached to our store cupboards and bread bins. The only time I have ever found Stegobium ‘in the wild’, was in a series of small ledges under arched supports of bridges over the River Wandle, in Wandsworth and Deptford Creek, in Lewisham, accessible only by boat. I poked out some of the grass, leaf litter and bird droppings accumulated  during the many years they had been the perfect shelter for feral pigeon nests. Stegobium was present in droves.

Perhaps pieces of bread and digestive biscuit had been brought back to these nesting ledges, although having seen pigeons squabble over the crumbs fed to them in parks, I suspect that if it is not swallowed at once it will be pinched by some other bird. In the end I doubt much human food gets returned here. On the other hand, the grass used to line the nest cavities was often heavy with seeds. It is these seeds, which would seem the obvious ‘natural’ food for Stegobium. Grass seeds, after all, gave us the staples of modern human food — wheat, oats, barley and rice — from which we have created biscuits, bread and breakfast cereal.

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