My mum recently had moths in her carpet and it looked exactly as you described. We treated the area with a flea spray for cats and dogs which was about £3.99 as the shop owner advised us that this would work. I then made up sachets using equal parts of the following herbs.
Dried rosemary
Dried wormwood
Dried sage
We had to get the wormwood on line from
http://www.baldwins.co.uk
I also used sage, rosemary, thyme, sandalwood and cedarwood essential oils. Basically the stronger it smells the more repellant it is to the moths. It seems to have worked, but you might need to go through your wardrobes and cupboards to see if you can find the source. They had made themselves comfortable in a pair of sheepskin slippers at my mums
