How to Bug Proof Your Home: Rodents

Pest Management In and Around Structures May 28, 2009 Print Friendly and PDF



Effective methods of rodents control include exclusion, habitat modification, trapping, and poison bait. The use of traps and/or poison baits can effectively provide short-term control. However, using the methods of exclusion and habitat modification described earlier can provide effective, long-term control by preventing rodent infestation.

House Mouse

House mouse
House mouse

House mice (Mus musculus) are the most common mammals in cities next to man and probably the most troublesome rodents in the United States. Their gnawing and nest building activities can cause structural damage. Often nests are made in large electrical appliances, where they may chew wiring as well as other insulation resulting in short-circuits or even fires. In addition, they are also health risk pests. House mice are transmitters of many diseases including the hantavirus, a virus that can target the lungs and cause pulmonary problems.

Roof Rat

Roof rat
Roof rat

The roof rat or black rat (Rattus rattus) is an Old World rodent species not native to North America. The roof rat is implicated in the transmission of a number of diseases to humans, including murine typhus, leptospirosis, salmonellosis, rat-bite fever, and plague.

It is also capable of transmitting a number of diseases to domestic animals and is suspected in the transference of ectoparasites from one place to another. In addition to consuming and contaminating stored food and feedstuffs, roof rats will gnaw on wiring (posing a fire hazard), and tear up insulation to use it for nesting material. The rats will feed on the fruit and vegetative portions of many landscape and garden plants including tree bark.

Roof rats are nocturnal (active at night). Roof rats prefer to forage for food above ground in elevated areas indoors and outdoors. They are agile climbers and travel through trees and along vines, wires, rafters, and rooftops.

They prefer to nest in secluded areas above ground in such places as attics, overhead garage storage, in the vine cover of fences or buildings, and in wood piles or other stored materials where harborage can be found.

Roof rats will also burrow in the ground especially in hot, dry environments. In these areas, they may use trees, materials stored on the ground, concrete slabs and sidewalks to support shallow burrows.


  1. Seal any gaps and holes and install door sweeps. Gaps of a 1/4 inch (the diameter of a pencil) permit entry of small mice, gaps of a 1/2 inch are large enough for small rats.
  2. Any previous rodent damage in your home must be repaired and protected from future attack. Use a strong material such as cement, mortar or appropriate sealants to fix gaps. Stuffing steel wool or mesh into rodent spaces only provides temporary protection. Filling cracks with a soft material like cloth will not stop the rodents from burrowing through and they will use the cloth for nest material.
  3. Employ proper sanitation procedures and eliminate harborage. Use pest-resistant food storage containers.
  4. Clean up the yard from clutter and ensure the compost bin is pest proof.
  5. Check for potential water sources that may be attracting rodents and have them repaired or removed.
  6. Secure garbage in proper rodent-proof containers.
  7. Harvest citrus and other fruit in a timely manner and pick up fallen fruit promptly.
  8. Prune shrubs so that the ground below them is clearly visible. Mow, trim, or remove ground cover plants that grow over one foot in height.

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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.