I have individual tubs. I did think of spraying the PAM on the outside of the tubs, but I was afraid that would not be effective at eliminating the bugs. You have a good point about preventing transfer of bugs from one enclosure to another.

I don't think I'll be using sevin dust. Even if the chemicals were safe, I'd worry about what the dustiness of it would do to the mice.

Another idea I read which sounded good was putting a flea/tick collar in the enclosure...well, it sounded good for about half a second until I thought about the mice chewing on it. Hey! New chew toy! nomnom. Hmmm. I think not!

I suppose I could look at the cost of the Frontline as a savings compared to the vet bill I thought I was going to have when I had the prolapsing problem.