WSU Extension


Brown marmorated stink bug
Clover mites
Cluster flies
Fruit flies
Fungus gnats
Giant house spider
Hobo spider
House centipede
House dust mites
House flies
Little house flies
Mice and rats
Moth flies (drain flies)
Multi-colored Asian lady beetle
Odorous house ants
Pavement ants
Root weevils
Seed bugs
Sowbugs and pillbugs
Spiders (non-biting)
Thatching ants
Western boxelder bug

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Caption: Roof rat (Rattus rattus)
Photo by: unknown
Mice and rats
(revision date: 4/21/2021)

Use Integrated Pest Management (IPM) for successful pest management.

These rodents are commonly problems wherever humans exist. Rodents will feed on just about anything including garbage, pet food, bird seed, meats, and nuts. Structural damage can occur from the rodents nesting and gnawing in and on the structure. Both mice and rats are generally nocturnal (more active at night) and if they are seen during the day it might indicate a heavy infestation. In Washington there are primarily two species of rats: The Norway rat and the roof rat. Norway rats have a tail that is shorter than their head and body combined. They build nests under buildings, low shrubs, wood piles, garbage dumps, and accumulations of junk. Roof rats, on the other hand, have a tail that is longer than their head and body combined. They are somewhat smaller than the Norway rat. They are also better climbers, building their nests in trees, attics, walls, or vine-covered fences. There are also two main species of problematic mice in Washington: The house mouse and the deer mouse. The house mouse consumes and contaminates many food stuffs because they tend to nibble on food and then discard it. Mice can also damage stored items or cause expensive appliances to malfunction because of their gnawing or nest building. The deer mouse is one of the most common mice found in agricultural and forest areas. This mouse prefers to eat seeds but will also consume fruits, insects, and fungi. Deer mice generally nest underground but will nest in hollow logs, or unoccupied buildings. Deer mice are also a primary carrier of Hantavirus, a dangerous, often fatal pulmonary disease.
Management Options

Non-Chemical Management
  • Keep food sources such as garbage, pet food, and bird seed in tightly-sealed, rodent-proof containers.
  • Repair cracks, small holes, broken windows and doors, and install door sweeps to keep rodents out of the structure.
  • Remove shrubs and brush near buildings that could provide shelter for the rodents. Manage compost piles.
  • Trap rodents by placing traps in areas they frequent. Look for gnaw marks, droppings, urine stains, and grease smudges on walls to know where to find the rodents.
Select non-chemical management options as your first choice!

Chemical Management

Non-chemical strategies are effective for managing rodents if used consistently. The bait products listed here should be used ONLY in conjunction with non-chemical strategies. Tomcat Rat Killer is labeled for use against both rats and mice; other products listed below are for MICE ONLY. Consult a pest management professional if you need additional assistance with rodent management.

If you choose to use a pesticide, some examples of products that are legal in Washington are listed below. Some products are labeled for just INDOOR or just OUTDOOR use, or may allow both uses. Be sure to choose a product appropriate for your situation. Always read and follow all label directions.
  • Tomcat Mouse Killer
    Active ingredient: bromethalin  |  EPA reg no: 12455-121-3240
  • Tomcat Mouse Killer III
    Active ingredient: bromethalin  |  EPA reg no: 12455-129-3240
  • Tomcat Rat Killer
    Active ingredient: bromethalin  |  EPA reg no: 12455-122-3240
  • Tomcat Rat & Mouse Killer - Child & Dog Resist Disposable Station
    Active ingredient: bromethalin  |  EPA reg no: 90780-9
  • d-Con Bait Station XI Kills Mice RTU
    Active ingredient: diphacinone  |  EPA reg no: 3282-102
  • Victor Fast-Kill Brand Bait Station
    Active ingredient: Bromethalin  |  EPA reg no: 36488-62
  • Harris Mouse Killer Refillable Bait Station
    Active ingredient: chlorophacinone  |  EPA reg no: 7173-303-3
  • This list may not include all products registered for this use.

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Caption: Roof rat (Rattus rattus)
Photo by: unknown