Boric acid. It kills just about any bug it comes in contact with, and from what I've read online, it's what professional pest control uses against carpet beetles. Put down a light dusting of it behind baseboards, crevices, etc. if you have light colored carpet, dust the entire carpet and leave it for at least a day before vacuuming. It's harmless to humans insofar as touching it. However, it is poisonous if ingested, so don't let small children or pets around it!