dos & don’ts: Rodentology

• Do the applied rodentology and don’t let the house mouse (Mus domesticus) masticate and contaminate structures and food. As a medically significant pest, the house mouse must be eliminated though integrated pest management (IPM).
• Do define IPM as inspection and investigation, identification, establishing threshold levels, implementing two or more control measures (cultural, physical, mechanical, biorational and chemical), and evaluating effectiveness.
• Don’t forget an exhaustive survey of the property must be conducted to define the scope of the infestation. Contiguous areas must be included in the survey. Immigrants will travel from other areas to exploit resources and return to refuges.
• Do know the signs a house mouse is present.

• New scats are shiny and soft, versus old scats, which are mottled, dry and fragile.
• Various scat sizes indicate the presence of young and mature mice.
• Urine pillars — repetitive layers of urine — indicate a well-established infestation.
• Cetimide is a chemical from urine that has an odor.
• Rub marks are tags along runways from the touch of a house mouse’s body (a mix of sebum, cholesterol and environmental dusts).
• Established house mouse paths can be repetitive travel routes along landscape, foundations, fences, sills, walls and utilities.
• Gnawing/mastication is also a sign. House mouse incisors leave a gnaw mark about 2 mm wide.
• House mouse refuges are globular and have shelf orientations.

• Don’t neglect the cultural controls clients can perform to improve sanitation. For example, organizational cleaning (storage and rotation), resource cleaning (cleaning agents), and exclusion or rodent-proofing.
• Do remember house mouse threats increase as service time and quality decrease — PMx = Dx + Rx (pest management = diagnostics + prescriptive products). pmp

Dr. Mitchell, D.O., Ph.D., M.P.H., B.C.E., a board-certified physician and entomologist, is principal technical specialist for PestWest Environmental, as well as PMP’s Technical Editor. He can be reached at docmitchell@northcoastmedia.net or 515-333-8923.