Also, if your dog has fleas and/or ticks, wash them in a solution of Dawn & it kills them on contact. Be sure to rinse ol' Rover thoroughly and put some moisturizing conditioner on him afterwards because it removes all the oil on his coat & it'll make him itchy.
Another "organic" method I have found for keeping ants & tree roaches out of the house is to spray around the doors and into the weep holes of the house a concentrated citrus oil. I use Orange Glow. It's highly toxic to anything with more than four legs and it works great!