Getting Rid of Carpet Beetles Naturally?

I killed a carpet beetle larvae in my walk-in closet a couple of months ago. At the time I didn't know what kind of bug it was, only that it wasn't a bed bug so I didn't think anything of it. (I had a mild bed bug infestation in my last apartment.)

Tonight, I found two more of these things in my linen closet so I did some Googling and was able to ID them as the varied carpet beetle larvae. I haven't seen any adults so I'm not sure where they came from. I also didn't see any holes in my sheets and clothes (knock on wood).

I vacuumed my apartment thoroughly and sprinkled some diatomaceous earth along the walls of my closets. I have no idea where the source of the problem is. I looked all over the interior of my apartment. My best guess is that they're coming from outside, another apartment unit, or maybe even the basement of the apartment building. What else can I do to prevent a severe infestation? I don't want to use moth balls and pesticides like a lot of websites suggest, because I have two cats.

By Amy