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Rodent Trapping and Chemical Control

Trapping and chemical control (also called baiting or rodenticiding) will only temporarily control rodents if no rodent proofing is done. Trapping and chemical control of rodents should be done after rodent proofing is completed.

Note: some rodents may carry diseases or parasites. If you will be cleaning up nests or carcasses after a rodent infestation, read this important information first.


  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 where droppings or rub marks are seen. Correct placement of snap traps is crucial to their effectiveness. It’s also strongly recommended to anchor snap traps in order to get a quick kill.
  4. Pre-baiting traps is an important step. Rats tend to avoid new objects. Place your traps, bait them, but don’t arm them. After the rats have taken the bait over several days, arm the traps. Follow the manufacturer’s label instructions for setting traps.
  5. Rats may learn over time to avoid traps, especially if you are not removing the carcasses every day. 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 or the type of trap used.
  6. Repeat the cycle of pre-baiting and trapping until no new signs of rat activity are seen.


How to clean up a rat or mouse from a trap


Chemical Control

A law was enacted in the state of California in 2021 that makes most anticoagulant rodenticides illegal for homeowners to use and purchase. There is a risk for all rodenticides to poison wildlife, pets, and small children, and these materials can be very toxic. The manufacturer’s label precautions and instructions should be strictly followed.

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

  • The chemical controls currently available as rodenticides are toxic to any mammal (including humans). Chemical controls should ONLY be used in tamper-proof bait stations to avoid accidental exposure.
  • Pets or wildlife that eat poisoned rodents may also become poisoned (called secondary poisoning). Be diligent about removing carcasses and dispose of them safely.
  • Rodents will sometimes die inside buildings in areas that are difficult or impossible to access, such as in wall voids, attics, or crawl spaces, causing bad odors.

Licensed private pest control operators have the materials and training to use chemical controls safely and effectively.



Page last reviewed: March 7, 2024

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