These nasty invasive creatures destroy carpets quite rapidly and their larvae are easy to observe wriggling around in the trash that used to be your nice Axminster carpet. Larval stages often abide in your loft in the nests of birds that have roosted there or in the soffits.
Unfortunately, they also eat furniture fabrics and clothes and being small, measuring about 3mm in length, usually the damage is observed first before the beast itself. The beetles are the adults and do little damage themselves excepting to breed more larvae. Treatment by a pest control practitioner is essential.