Don't despair, you can be rid of them quite cheaply with a product sold on Amazon for £12.99 inc postage. It's in a spray bottle (500ml) with a black and yellow label, sold by Rugremedy and called 'carpet moth killer'. It's water based, odourless and really does work. Takes about half an hour to dry.
We had an infestation in the lounge and dining room. We had to pull out the furniture and spray all around the edge of the carpets. The grubs can be anywhere dark so you also need to spray under chairs and sofas, the backs of furniture, under rugs, pouffes, check also behind pictures and mirrors on the wall and inside and on the back of wooden furniture. Look at the backs of your curtains and also between the fabric and linings.
One bottle was sufficient to do downstairs but as a precaution, I bought two and treated upstairs aswell. It was hard work but worth it. Several friends use it now, we all find it excellent. I keep a bottle in the house and spray my carpets one a year, never had a problem since.