I would like to address a few of the comments.....
1) The electronic devices don't work at all, under any circumstances.
2) A well fed cat has no desire to catch mice, and when it comes to rats, a smart cat will stay away from them, knowing that a rat can do a lot of damage to a cat. There are exceptions, but usually the outcome is the cat looses. Some mice keep cats company when you are not home.
3) Mice can breed approximately every 6 weeks and their life expectancy is about 1 year, unless they get picked off by a owl or some other predator. Female mice become sexually mature at 6 weeks after birth and males at 8 weeks. If you do the math, a pair of mice can quickly multiply to the point that you have a major infestation.
4) Mouse poisons such as Decon are anti coagulant type of poisons. The chemical name is Warfan, the same type of product is given to humans for heart disease. When a mouse ingests the poison, and then slips through a small hole, the body gets bruised, and that bruise will bleed internally until the mouse dies from hemorrhaging. I have heard that some mice will develop a resistance to this form of poisoning, but I have never been able to confirm this independently. I don't use Decon, but another product that was manufactured by Purina called Assault. I found that it worked better for my mouse control. I suggest that you change brands of poison periodically to assure that the poisons will continue to work.
5) The old fashioned mouse trap is still the most effective way. Mice run along the walls, not across the floor, so place the traps along the walls whenever possible. If the mouse trap has become contaminated with blood, then wash it in hot running water before you reuse it.
6) Mice are cannibalistic if there is a shortage of food. They will devour any carcass that is in a trap. They will also eat a poisoned mouse, and that in turn is how they develop a immunity to the poisons, so I believe.
7) If your cat eats a mouse that has been poisoned, it will not harm the cat. The poison isn't that strong and the cats body will not have a negative reaction to the poison. I got this information a long time ago from my veterinarian.
House Mouse Prevention & Control
Dusty