Safe Rodent Control

      Nontoxic rodent control
      Metro natural gardening segment for KATU AM Northwest
      Carl Grimm, December 19, 2011

      T'was the holiday season and all through the house, not a creature was stirring except maybe a mouse But never fear, Carl Grimm from Metro is here to help you keep critters away using least-toxic controls.

      Beware of rodents - and of toxic baits
      Rodent feces can transmit some diseases and rats can bite people and damage structures. But beware of toxic baits, too. Several baits now on store shelves pose an unreasonable risk to children, pets and wildlife, and their manufacturers have refused rulings from the U.S. Environmental Protection Agency to remove them from stores. Any bait that is uncovered is dangerous. Baits that are in tamper-proof enclosures are better, but only as a last resort, and only for use outdoors, since rodents poisoned indoors can rot in walls and smell terrible.

      The best strategies to keep rodents away are removing food, shelter and access and then using traps.

      Don't feed the wildlife
      Wipe kitchen counters well and put away all food in airtight containers, ideally in glass jars or tins.
      Don't leave pet food out for more than a half hour, and keep bird seed, chicken feed, fallen nuts and fruits, and garbage off the ground outside.
      In general, avoid clutter in the yard and home. Firewood should be at least 18 inches off the ground and vegetation at least 3 feet from the foundation. Boxes and piles of stuff should not be on the floor near walls inside.

      Keep 'em out
      Rodents can pass through holes larger than a 1/4 inch. Rats can chew small holes into large ones. Cover all entry points to your home, including unscreened crawl space openings, vents and window gaps, pet doors, gaps in garage doors and around pipes or wires entering walls, and uncapped floor drains. Use sheet metal, screening, wood, or caulk to seal holes. Be sure products you use are low VOC and do not have cautions in the label's fine print about cancer, reproductive harm or other impacts.
      Keep garbage cans and yard waste bins shut tight. If necessary, use bungee chords.
      For compost, use a rodent-resistant bin (with a lid, floor and no holes larger than 1/4 inch).

      Use traps and clean up rodent messes
      Trap types include snap, glue, multiple catch and electronic. Whichever one you use, always place them against a wall or other vertical surface, and in the areas you have seen the rodents or their droppings.
      Place snap traps so rodents are likely to pass directly over the trigger. Put a lot out - a dozen is not too many. Place them in pairs end to end or with triggers towards the wall so rodents cannot jump over them easily.
      Use different types of bait at the same time. A smudge of peanut butter on some, cheese on some, small pieces of bacon or cracker tied on to others with string.
      To protect pets and children from snap traps, put them in small cardboard boxes with holes cut on either end. Or you can use glue, multiple catch or electronic traps. But glue and multiple-catch traps do not kill the mice, so you will have to drown them in a bucket or otherwise euthanize them.
      Dispose of dead rodents in a plastic bag in the trash.
      Wear disposable gloves while cleaning up rodent feces, and do not vacuum or sweep them up. Instead, soak them with a 10% bleach solution and let stand for at least 20 minutes. Then use newspaper, paper towels or rags to wipe droppings up. Bag up and dispose of everything in the trash. Wash your hands and launder your clothing when you are done.

      For serious infestations, call a professional
      Look for a certified prevention-based, least-toxic company at Be sure to ask for least-toxic, prevention-based controls and get a plan and a guarantee in writing.

      If you have a recurring problem with rats
      You may have a sewer line break. Call your county vector control office or Extension Service for specific instructions:
      Multnomah County Vector Control: 503-988-3464
      Clackamas County Vector Control: 503-655-8394
      Washington County OSU Extension Service: 503-821-1150

      Remember these tips so you'll be sure to have "not a creature stirring, not even a mouse," and have a happy holiday!

      Need more information about keeping your home free of hazardous chemicals? Call Metro at 234-3000 or visit