A friend has been having the same problems (old house out in country, with all the external integrity of swiss cheese). We tried the non-toxic baking soda, flour, sugar thing from this vid and it seemed to work. We tried both the salt version, and the sugar...and the sugar won out and got results. As a bonus, as my friend said, "I don't have to worry about crazy, industrial grade poisons in my house too."
Oh man, that's cool that something natural actually worked for you! If I put sugar out, I'd probably wake up to ants. I'll check out that video though.
Thanks for reading!