How do you tell mice from rats, and what does the sign mean?
The size of the droppings, the gnaw marks and the tracks give a rough guide to the species. Mice leave small, pointed droppings and rats leave larger, blunt ones, and the age of the sign shows whether the activity is recent.
Droppings are the most useful sign. Mouse droppings are small and pointed, and they are scattered along a route. Rat droppings are larger and blunter, often found in the corner of a room or along a wall. Fresh droppings are dark and moist, and old ones are grey and dry.
Gnaw marks tell a similar story. A mouse leaves a fine mark on a box or a cable, and a rat leaves a broader mark with heavier teeth marks. Marks on a door bottom or a wire can show the route, and the inspection checks them against the gap they point to.
The sign is worth reading in context. A sound in the ceiling at night, a smell in the attic and droppings in a pantry point to different routes, and the inspection follows each one before choosing the plan.
Why is sealing as important as the bait?
A rodent that can get in will keep getting in, so the bait or trap reduces the animals already inside but the seal stops the next arrivals. Doing one without the other leaves the job half done.
A mouse can fit through a gap about the width of a pencil, and a rat through a hole about the size of a coin. The inspection looks for gaps at pipes, wires, vents, the eaves, the crawl space access and the bottom of doors, because those are the routes that let animals in.
The seal must be made of material that rodents cannot chew through. Metal mesh, a durable filler and a metal flashing are common choices, while soft foam and thin plastic are not. The seal is checked after the work and again at the next visit.
The timing matters. Sealing a route while animals are inside can trap them in the wall, where they die and cause a worse smell. The plan removes the animals first and then seals the route, unless the inspection finds a reason to do it in another order.
What clean-up keeps the rodents from coming back?
Removing food and cover near the house is the other half of the job. The AgCenter advice on wood, cardboard and cellulose and on keeping mulch back from the foundation applies, because those items give rodents shelter close to the wall.
Food is the first thing to clear. Pet food left out, open bags of feed, unsealed pantry food and food scraps near a bin give rodents a steady supply. Storing food in sealed containers and taking out the bin regularly removes the reason to stay.
Cover is the second. Stacked wood, cardboard boxes, pallets and debris against the foundation give rodents a place to rest, nest and approach the wall unseen. The AgCenter advice is to remove wood, cardboard and cellulose from around the home, and that advice serves rodent control as well as termite prevention.
Mulch and vegetation against the wall are the third. A dense bed of mulch or a thicket of plants at the foundation gives cover, and keeping it back from the wall reduces the approach. The foundation clearance review sets out the distances.
How are traps and bait placed, and what should the owner watch for?
Traps are placed along the walls where rodents run, and bait is placed where it is safe from children and pets. The owner watches the traps, the signs and the entry points, and reports any new activity with a date.
Rodents run along walls and edges, so traps are set against the wall with the trigger facing the wall. Bait is placed in a secured station where it cannot be reached by children or pets, and the placement is recorded against a plan of the building.
The owner's job is to report. A trap sprung on a check, a new dropping or a new scratch is information, and the plan should be updated with the date. A sign that keeps coming back after the work is a sign that a route has been missed.
Keep the traps and the bait out of the reach of children and pets, and do not move a station without telling the service. A moved station can give a false result, and a loose bait can be eaten by a child or a pet.
