Rodents urinate continuously, contaminating everywhere they go. A rat expels up to 5.5 liters of urine per year. Rats produce about 40 droppings per day, mice about 80.
Cutting off sources of food and water for rodents is the first step towards elimination. Store food, birdseed, pet food, garbage, compost, and recyclables in secure metal, glass, ceramic, or heavy-duty plastic containers with tight-fitting lids. Feed pets at scheduled times. Put unfinished food in the refrigerator. Promptly clean up spills and crumbs. Keep bird-feeding areas clean of spilled seed. Move firewood, garbage cans and debris piles away from the house.
Next, entry points need to be identified and sealed off. Poke steel wool or wire mesh into entry holes with a screwdriver or attach flashing. Prune branches away from the roof. Seal openings underneath and behind appliances with latex caulk. Seal gaps around water, gas, and heating pipes, heat registers, air ducts, electrical chases, and false ceilings.
Rats tend to be very shy and cautious animals. When confronted with a new object in their environment, such as a trap, they will often avoid it for days until they are used to its presence in the area. They have poor eyesight so they leave behind a strong pheromone odor telling them where to run. Set traps at night, when mice and rats are most active, and check or remove them in the morning. A dab of crunchy peanut butter on the trigger is an enticing lure. Live trapping with box traps or glue boards may be used for monitoring and for removal. It's better to trap intensively for a few days than to set only a few traps for a long time. Snap traps can be attached to rafters with nails and to pipes with wire. The trigger should snap towards the wall.
Rodenticides are sold in many different forms, including pellets, powder, blocks, and meal. If you choose this option, follow the manufacturer's label carefully or work with a professional. They are very effective in eliminating domestic rodent pests. Pesticides can be hazardous to children, pets, and wildlife. In addition, animals that eat poisoned mice could be poisoned themselves. Poisoned rodents may die inside walls and sub floors where they cannot easily be removed. Their slow decomposition creates foul odors and attracts other pests, such as flies and beetles.