Controlling rats and mice is more than just plugging entry holes, setting traps, and putting out poison bait.  The best control is to take away available food, water, and shelter.

SANITATION

The first step is a cleanup program.  Rats and mice find shelter under old lumber piles and stacked firewood (should be stored 18 inches off the ground), piles of old papers, boxes, bags, broken-down sheds, trash dumps, high weeds and abandoned vehicles.  All such areas must be eliminated or corrected.  Any control program without environmental improvement will be ineffective.  These rodents can rapidly restore their original population levels due to their high birth rate.

Interior sanitation also needs to occur.  Once rats or mice are in your house, their population levels will increase if there is available food and water.  Remember rats will eat about anything.  If there is a cockroach problem, rats or mice can feed on the insects.  Clean up food crumbs and fix water leaks.

RODENTPROOFING

This means stopping the movement of rats and mice into buildings or other areas where they are not wanted.  Rats can squeeze through a hole the size of a quarter; mice can move through a hole the size of a dime.  Favorite entranceways are poorly fitting doors and windows, holes around lead-in pipes and wires, dryer vents, joints between building foundations and walls, cracked siding, and unscreened doorways.  All such openings should be closed using sheet metal, hardware cloth or cement.  Doors and windows should be adjusted to close tightly.  It is also important to have tight-fitting covers on floor drains.

POPULATION REDUCTION

There are five methods generally used for population reduction:  trapping, glue boards, burrow fumigation, tracking powders, and oral toxicants.

• Trapping is a practical way of removing rats and mice, especially where poisons might be hazardous and where odors from dead animals would be objectionable.  The most effective and versatile trap is the wooden-based snap trap.
• Glue boards involve the use of a non-toxic sticky substance on heavy squares of cardboard.  They are placed in active runways.  When the animals become trapped, they are killed and the board is thrown in the trash.  These are well-suited for restaurants and food-handling establishments.
• There are several chemicals federally-registered for use as fumigants against commensal rodents.  They should never be used where there is danger of people or non-target animals coming in contact with the gas.  For that reason, most fumigants can only be used by professional pest control operators.
• A tracking powder is effective when food is plentiful.  They work by having the rodent come into contact with it; then the rat or mouse cleans itself; and, the rodent ingests the poison.  Tracking powders should never be used in areas where there is any danger of the powder coming in contact with food or surfaces where food is prepared.
• There are two general types of oral poisons:  single and multiple doses.  Killing success with single dose poisons depends on the animal consuming a lethal amount at one meal.  Multiple dose poisons have a lower concentration of toxicant.  They rely on several days of consecutive feeding.  No toxic bait is 100% effective.  Trapping is necessary for every last rodent to be removed.  Also, placement of bait inside a structure can cause several problems.  Children or pets may eat the bait and have adverse reactions.  Rats and mice that eat the bait may die in a wall void or other unreachable areas and produce a decomposing odor.