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Rodent Trapping and Control

Note: some rodents carry hantavirus, a potentially deadly infection that is transmitted when humans breathe in dust contaminated with the body fluids of infected rodents. If you will be cleaning up after a rodent infestation, read this important information first.


Trapping rodents is a perfectly acceptable method of control. It should be done after rodent prevention techniques and rodent proofing is completed. Trapping is especially desirable when rodenticides cannot be used near food, small children, or where domestic animals or livestock are present. Traps should be used indoors to prevent the serious odor and fly problems that can occur when poisoned rodents die in walls.

  1. Before any trapping, first determine where rodents are entering structures or where rat activity is occurring.
  2. Bait selection is important for trapping success. Peanut butter, nuts, bacon, pieces of apple, and moistened oatmeal are effective baits.
  3. Place traps perpendicular to runways along fence tops and next to walls. Correct placement of snap traps is crucial to their effectiveness.
  4. Pre-baiting traps is an important step. Rats tend to avoid new objects. Pre-baiting involves placing baited traps without setting them. This step allows rats and mice to become familiar with the traps. Place pre-baited traps in areas of rat activity for a few days.
  5. After a few days, set baited traps perpendicular (at right angles) to active rat runways where droppings are seen. Follow manufacturer’s label instructions for setting traps. Before setting, securely attach bait to the trigger.
  6. When the number of animals captured per day declines, check for fresh droppings. If droppings are still observed, the rodents may be avoiding the traps. Change trap location to new area of rat activity.
    Repeat the cycle of pre-baiting and trapping until no new signs of rat activity are seen.
  7. Some rodents can carry Hantavirus or other diseases. Therefore, when cleaning rodent areas, do not stir up dust by sweeping and vacuuming droppings, urine, or nesting material.
    Using rubber or latex gloves, apply a disinfectant or a 10% bleach solution onto dead rodents and droppings. Clean up with paper towels. Double-bag and dispose of waste in a garbage can with a tight-fitting lid. Afterward, thoroughly wash hands with soap and water.

Information about rodents and disease can be obtained from the District laboratory at (650) 344-8592.


How to clean up a rat or mouse from a trap



Chemical Control

Most rodenticides presently available for rat or mouse control are anticoagulants (stops blood from clotting). Commercial brand rodenticides are available at plant nurseries and hardware stores. The manufacturer’s label precautions and instructions should be strictly followed.

Residents should consider these important points when considering the use of chemical control:

  • These products are very toxic to people and animals! Rodenticides should ONLY be used in tamper-proof bait stations to avoid accidental exposure to children and pets.
  • Rats and mice ingesting rodenticides will sometimes die inside buildings in areas that are difficult or impossible to access, such as in wall voids, attics, or crawl spaces.

These products are very toxic to people and pets!

For assistance with any of these trapping techniques, or to schedule an inspection, please contact the District at (650) 344-8592.

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