Unidentified Insect

It looks a lot like a carpet beetle larva. (Do you keep a laundry basket in the bathroom? Check it for more, or for the dried molts.)

If so, it should do well in your Terrarium; they're tough little characters. I've had one in a jar for months. I haven't fed it; it's housed with just a scrap of feather and wool. I just checked it now for the first time this year. Doing fine.

I wouldn't want one to escape, though.

I have several blog posts about the beetles; here's a decent photo, though the long hairs on the tail are almost invisible: http://wanderinweeta.blogspot.com/2009/10/shameful-failure-at-hospitality.html

Or plug "carpet beetle" into the search box on my blog; I have quite a few posts about them.

Thanks; that is our guy alright. I have noticed some of the adults dead on our window sills, so the invasion now makes some sense.

Unlike the house centipedes, I suppose this is one critter I should not try to live in harmony with.