It sounds like you need to have a thorough inspection of your home. Mice need only a 3/8-inch gap to enter. Simply laying out toxicants without finding the openings and closing them, as well as reducing food and habitat in the surrounding property, is a recipe for continued problems, as you have discovered.
Find the openings. Visit http://icwdm.org/Inspection/Default.asp and click on the link on inspection techniques to go to a free online course on how to inspect. Then at least you will know how your pest controller should be inspecting.
Next, make sure you don't have bird feeders on your property that haven't been modified. Bird feeders spill food, which helps to increase mouse populations. If your home has been invaded by mice, you've probably been feeding them as well, if unwittingly. Carefully examine your home for every possible source of food and evidence of feeding: kitchen, pantry, garage, garden shed, etc. Look for anything that mice might eat: grass seed, pet food, stored food products, etc. Permanently place these in rodent- proof containers of glass, metal, or heavy plastic. Eliminate all products that have been fed upon by mice. Carefully eliminate all traces of spilled product.
Third, control aggressively. The fact that toxicants used by your pest controllers "worked" is evidenced by the noise reduction. The mice died. The bigger issue is that the holes were not closed, and other mice reinvaded your home.
To learn how to secure your home against mice, visit these two Web sites: http://www.ianrpubs.unl.edu/epublic/live/g1105/build/g1105.pdf and http://www.ianrpubs.unl.edu/epublic/pages/publicationD.jsp?publicationId=23. They will provide you with research-based information.
There is no magic solution—just a lot of hard work. But your problem is solvable for the long term provided the proper steps are taken and a thorough effort is made.
You can also read our tips for how to hire a professional. It will help you find a qualified professional Wildlife Control Operator National Directory.
It is always prudent policy to request at least three written quotes whenever a major pest control project is undertaken. Request specifics. It is also prudent to ask for references. It's your home and your money; protect thoroughly, spend wisely.
