How to Use Instant Mashed Potatoes to Kill Field Mice

Updated November 21, 2016

Microtus pennsylvanicus, or the field mouse, is a stocky rodent measuring 4 inches long with partially concealed ears and short legs. Its fur is grey or reddish brown with black tips. Field mice squeeze through cracks to enter a home, and eliminating them is essential as they are known to carry fleas, worms and diseases transmittable to humans. Avoid chemicals by putting out mashed potato flakes. Mice eat the flakes, which swell on contact with stomach moisture and kill them.

Find where field mice are nesting in the home. They like being inside walls and under sinks where there is access to water, so inspect places such as laundry and bathrooms, hot tubs and kitchens.

Check for mice trails along walls. Field mice travel the same runways between food and nest areas, which are usually close to walls. Confirm their presence by looking for droppings. Field mice leave 3/16-inch, pellet-shaped droppings that are green when fresh and fade to brown or grey. Check 10 to 30 feet on either side of the trails for others signs of mice.

Locate entry points along the trail. Field mice are able to chew through most materials to enlarge tiny cracks and create numerous small openings in baseboards. Place 2 tsp of instant mashed potatoes in piles along the travel route between entry points and the food supply. Field mice are attracted to different things and sample new foods.

Where children or pets are present, make bait boxes out of cigar or cardboard boxes with openings on opposite sides. Mice like to eat in concealed areas, and bait boxes prevent pets and children from getting at the mashed potato bait.

Check the piles of potato flakes regularly. If they are smaller or there are droppings nearby, it's likely field mice are eating the potatoes. Replenish the mashed potato flakes in the potato piles until there are no more signs of mice eating them.


Sanitise mice-infested areas with bleach using gloves after mice have been eliminated.


Handle dead mice with gloves, and wear a dust mask when vacuuming or sweeping infested areas.

Things You'll Need

  • Instant mashed potato flakes
  • Gloves
  • Bleach
  • Dust mask
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