I live in a residential development, but we have caught 3 field mice in our basement this week, which is finished. The seem to be staying in the basement, as we haven't caught any elsewhere in the house. We can't figure out how they are getting in. Does anyone know what we should be looking for on the exterior of our home, which is siding. Also, is there anything we can put in our yard to keep them out? My husband said he thinks there is a device that sends out high pitch signals that keeps them away. Help!!!