Philip Hensher: The plague in our cashmere-filled closets

I said goodbye to an old friend yesterday morning.

When I got my results for my degree, twenty-five years ago this summer, I decided to celebrate by buying something I would always love. I went to the wonderful Oriental Rug Shop in Sheffield, and bought my first carpet. It was – it's hard to talk about it in the past tense – a Qashqai, a beautiful object. It cost £750, which seemed like a lot to a student in 1986. But I don't think I ever regretted it for a moment.

We've bought other beautiful carpets since then, some with quite dramatic histories. But I always loved my Qashqai best. George Bernard Shaw asks rhetorically "Who ever looked at beauty when it has been three days in the house?" Well, you do take pleasure in a lovely carpet, I believe, and this one has followed me round ever since. Yesterday we had to throw it out. I'd been defending it and apologising, and promising that something could be done, but yesterday I had to admit defeat. There's an empty space on the floor, and the silent companion of a long stretch of my life has disappeared. "Sentimental value" is the phrase. I don't see why you can't love a unique, irreplaceable object with perfect sincerity.

Or, come to that, hate with a passion the small brown things – Hofmannophila pseudospretella might be the Latin name – that have munched their way through it, in the dark patch under the bed. Moths! I first became aware of them a couple of years ago. A friend said casually, "You've got a hole in that sweater". I looked, and it was so. It was in a curious place, where it couldn't have been through wear or cigarette ash falling on it. I couldn't think what it could be. I put on another sweater a day or so later, one I didn't wear so often, and this one, horrifyingly, was like lace in places. I shook it, and out of the dark of the back of the wardrobe flew three or four small brown things, with that nauseating, uncommitted, half-hearted attempt at flight. I've come to think they are just too stuffed with cashmere canapés to take off with any energy.

I have no awareness of any plague of moths before the turn of the century. Explanations differ. Some people think that it's to do with general warming, which seems unlikely after such a cold winter. Or central heating. Or the spread of cashmere as an ordinary material for clothes – it was seriously "luxe" thirty years ago, but now everyone's got it in their wardrobe.

Personally, I think the explanation is this. Sometimes, for no rational reason, waves of pure evil arise in the world, at the idle bidding of Satan. There is nothing for us to do but hunker down, heads in hands; wait for the flood of evil to pass; and prepare to buy new sweaters for ourselves every three months. Before you write in with the solution, I have to say that we've tried everything, and nothing seems to work. We've tried freezing all our clothes, and the moths were back within a fortnight. We've tried mothballs – I actually saw a fat moth sitting on top of one, smugly cleaning whatever moths have instead of whiskers. John Lewis succeeded in selling us some cedar strips, "the natural deterrent". Ha, ha, ha – like tough South London moths are going to run from a bit of wood.

We've tried an unbelievably macabre device, a strip of gluey paper imbued with moth pheromone. That one certainly trapped the moths, if you had the stomach to watch them die slowly in apparent agony. (Some members of the household were of the opinion, by now, that they thoroughly deserved it; others were more squeamish.) Anyway, that didn't work either, since the moth pheromone had the side-effect of luring in every moth from five hundred yards around.

Once you had broken the shame of admitting an infestation, friends and acquaintances chipped in with their horror stories. Someone in Devon told of an Asian moth so ferocious that it could actually eat through plastic– so much for those giant Ziplocs. Another said, helpfully, that the chemicals in the old-style, effective mothballs were now banned in the UK, but could still be had in India and Bangladesh. In-laws were dispatched to inquire in the stores of Dhaka and Calcutta.

A Christmas present to my mother, a cashmere shawl from Jaeger, was shredded by our moths almost before we could hand it over. The moths started to move on from our sweaters to our trousers. I started to eye polyester jumpers longingly, to wonder what was so bad about artificial fibres anyway; and one terrible day, putting that beautiful piece of music, Ravel's Miroirs, I found myself skipping over the movement called Noctuelles. Ravel captures their indeterminate movement just too well. It had got to the point where I couldn't listen to a piece of music about moths.

"Have you considered – they're coming from somewhere," a fellow sufferer said. We emptied the wardrobe, but it seemed to be more of a meeting place, a clubhouse, than their cosy home. And then we took the bed up, and there it was: my lovely Qashqai, chewed to bits, and a horrible gritty substance mixed with the digested wool which was, what, their shit, their eggs? Better not to think. "Please," I said. "I'll spray it. We'll cut out the holes. The worst bits can stay under the bed." But it was no use. I knew we would wage a pathetic, long-running war of attrition; it would take on the psychic dimensions of war, not against the evil of the moths, but against my beloved carpet, snipping and trimming as the months went by. I bit the bullet. The carpet went out with the bins. And as I dropped it in, a small, brown, flapping object rose, indomitable, indestructible, unafraid. I wonder if Jeyes fluid would work.