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Facts About...

Rodent Control


What is it?

Rodent control means the elimination or reduction of rodents in and around buildings or lands used by people for work, leisure, or shelter. Rodents such as the Norway rat (also known as brown, common, and sewer rat), the roof rat and the house mouse commonly require control.

What is the problem?

Rodents eat almost anything, breed quickly, damage buildings and can be carriers of disease which can spread to humans. In a year a pair of mice can eat over 4 kilograms of food and leave about 36,000 droppings. An adult rat can eat 20 to 40 kilograms of food per year. Given the right conditions, a single pair of rats and their offspring can grow to very large numbers. Rats and mice contaminate about 10 times more food than they eat and can damage buildings and other articles by gnawing through rubber, aluminum and other soft metals (even light steel), cinder blocks, plastic and wood. Mice need only a 6 millimetre space and rats a 12 millimetre space to get through an opening. Rodents carry mites and fleas and spread diseases such as salmonella and Hantavirus.

How do I know if I have a problem?

The easiest way to identify a rodent problem is by seeing their droppings: black, rice-size droppings suggest the presence of mice; and black, bean-size droppings suggest the presence of rats.

Other signs of a problem include:

  • Burrows - fresh digging around foundations and into walls (rats)
  • Runs - dust-free “pathways” along otherwise dusty walls and floors (rats or mice)
  • Gnawing Marks - on wood, concrete or other materials if entries or food/water are nearby
  • Sightings - mice in daytime are common; rats in daytime indicate over-crowding; “for every rat seen, suspect 25 unseen”
  • Smudge Marks - greasy film left by fur along walls, often associated with “runs”

How do I control rodents?

There are many things you can do to control rats and mice. Good sanitation is most important.

  1. Rodent Proof Buildings - Seal outside openings where rodents can enter your home with the use of coarse steel wool and sheet metal around pipes and electrical conduits.
  2. Eliminate Harbourage - Good housekeeping is very important. All stored items should be kept 24 to 30 centimetres off the floor for easy cleaning. Clearing brush and trash from around homes and buildings reduces hiding places for rodents.
  3. Remove Food and Water - All water leaks should be repaired immediately and spills cleaned up. Food items should be stored in rodent-proof storage containers.
  4. Control Existing Population - Traps and rodenticides may be used to reduce or eliminate existing populations.

Traps involve the physical trapping of rodents. Always place enough traps: 1-2 metres apart for mice, and 7-10 metres for rats. Make sure you use the correct trap (rat traps for rats, mouse traps for mice). Concentrate on areas of high rodent activity that are inaccessible to children and pets.

Rodenticides are chemicals which are used to kill rodents. Concentrate on areas of high rodent activity that are inaccessible to children and pets. RODENTICIDES ARE POISONOUS TO HUMANS AND OTHER ANIMALS!

ALWAYS READ AND FOLLOW THE LABEL DIRECTIONS AND PRECAUTIONS

How can I protect myself?

Treat all rodents as infectious. Dead rodents, their urine and droppings should be handled with gloves and disposed with household garbage in tightly sealed bags. Any foodstuff contaminated by contact with rodents or their droppings should be discarded. Special care should be taken with mouse droppings and urine. A wet method of cleaning should be used, such as wet wiping or mopping with a household disinfectant. Wash your hands after handling traps, poisons, rodents and wearing gloves. A licensed pest control operator should be contacted for heavy infestations.

Additional resources

More information can be obtained from

Durham Region Health Department, Environmental Help Line 905-723-3818 or 1-888-777-9613

April 22, 2013