You can use safely diatomaceous earth. There are very finely ground commercial products that come in cans and it can be puffed out in a light dust. This is also good for ants and many other pests. You can eat the stuff, but it is best not to inhale it. Never use the DE intended for pool filters, that is impure and can be noxious.
I just sent a can of it to a friend in NYC who is having problems with them in his apartment. Can't quite get them to stay away, even after pest control treatments, so he's trying this now.