We have a rule here; tenants that don't pay rent aren't welcome. I have had literally thousands of dollars of damage from mice.
Living in a 100+ year old house, mice have always been a problem. Before my second marriage, cats provided a solution but the new wife has a phobia about cats so they went and the mice came. Diligent setting of traps would keep them under control but after a few weeks of no activity the vigilance goes lax.
Two years ago, I posed the question to the internet, "How small on opening can a mouse get through?". The consensus was if you can fit a pen in the hole the mouse can get through. So I crawled around the foundation, sealing any crack or crevice more than 1/4" in size with mortar. The building technique for foundations 100 years ago used mortar for the outer layers in the 20" foundation but the inner core was loose rock so a breach of the outside layer would lead to a labyrinth of passages. Mortar back then was also lime mortar which tends to crumble over the decades
The house doors are all sealed weather tight so they were OK. The basement entrance was an issue as that door was old and had a less than perfect seal. I put a couple of screen door closers on the door and we keep a stop on the door to ensure that it is closed. For almost two years, there was no sign of a mouse.
Then, about a month ago, as we were watching TV, one skittered across the living room floor. With all the work outside, we had become lax in checking the basement door and several nights, there the door was left slightly ajar. I suspect that a family took up residence as I have trapped a number of them since. Hopefully, with diligence, I can clean out the infestation and we'll be good again.
The woodworking shop is hopeless as that building is even older with no chance of a hermetic seal. It is strange that having all the nice pine shavings from the planer that the critters have a distinct preference for user manuals as nesting materials
Same goes for the forge. Last year, I had to rebuild my Miller welder because a mouse crawled in through a vent slit and made a nest on top of the secondary wiring. I had a similar issue where a mouse built a nest in the insulation of a lab convention oven.
And so it goes, the barn, my boats, the tractors. They had even built a nest in the air intake and chewed up the ignition wiring of my wife's Audi.
I don't use poisons as I don't like dead mice decomposing in inaccessible places. The old fashioned Victor traps with the metal trigger pan work well. The pail with water and pivoting paddle also works.
Maybe it's time for a pet ferret.
