Rodent Control

Vector Control actively monitors City owned property to prevent and treat rodent infestations. City of Norfolk residents should take steps to reduce rodent populations by reducing food sources, eliminating harborage, and treating infestations when necessary.

Rats and mice are responsible for the spread of a number of diseases, either directly, by contamination of food, or indirectly, by way of rodent fleas and mites.

Rats continuously gnaw to keep the growth of their teeth in check and to gain entrance to obtain food and shelter. Rats destroy approximately ten times more food through urination and defecation than they actually eat. Additionally, numerous fires have been started by rats chewing through electrical wiring.

Rodents of Public Health Concern

  • House Mouse - The house mouse is identified by a small slender body. The ears are large, the tail is semi-naked and is as long as the head and body together.
  • Norway Rat - The Norway Rat has a stocky body. The tail is not quite as long as the body and head together. Norway rats weigh between 12 and 16 ounces. This species is larger, stronger, more aggressive, and better adapted for producing young and surviving in colder climates than the roof rat. Indoors, the Norway rat prefers to nest around the floors of buildings, but when populations are large, it will occupy attic areas, suspended ceilings and under floors. Outdoors, the nesting places are often in burrows alongside of foundation walls.
  • Roof Rat - Roof rats are smaller and sleeker in appearance than the Norway rat. Their ears are larger, and their nose comes to a more pronounced point. Whereas Norway rats live in burrows or under floors. Roof rats prefer to live in areas elevated above the ground. Roof rats can be thought of as "vegetarians" as they prefer to eat seeds and plant foods such as fresh vegetables or fruits.

The territories of most rats are between 50 and 150 feet radius around the nest. If need be, however, rats will travel 1300 feet or more daily to obtain food and water. In urban areas most rats remain around the buildings and yards which provide their necessities, and unless they are disturbed, they do no move great distances.

Rats constantly explore and re-explore their surroundings, but are wary of new foods, new objects, or changes in their environment. This is termed "neophobia" which means " a fear of new". This neophobic behavior may last for several hours or even for several days. Even a change in position of a familiar object causes suspicion. This is why traps and bait boxes are sometimes avoided for several days.

Recognition of a Rodent Problem

Important signs of a rodent infestation are:

  • The presence of live or dead rodents.
  • Rodent nests. These can be made up of many kinds of materials, such as bits of paper, straw, rags, etc.
  • Rodent odor. A distinct odor from rodent urine may indicate the presence of rodents.
  • Droppings. The presence of droppings can indicate activity and possible severity of the problem.
  • Evidence of gnawing. Rodents gnaw in an attempt to obtain shelter and food, also to keep their front teeth, which grow constantly, from becoming too long.
  • Rub marks. Deposits of body oil and dirt from rodents found along frequently traveled routes may be used as an indicator of habitual pathways.
  • Tracks. Footprints indicate the presence of rodents and furnish information regarding places where they travel or which they frequent.
  • Rat Burrows. Burrows consist of tunnels dug below ground and are used by rodents for nesting and as a path for travel.

Rodent Control Measures


Food source removal is a key component for successful rodent control. Garbage, food, or feed should be stored in sealed containers. Spilled food and garbage should be cleaned up regularly. Outside debris and vegetation should be eliminated, as it provides essential harborage. Use the following checklist to ensure your property is protected:

  • Eliminate weeds from the exterior of buildings and maintain an uncluttered, weed-free perimeter of at least three feet around buildings.
  • Trim any tree branches overhanging buildings, they can be used by rodents as a travel path into your home.
  • Eliminate any outside debris, such as old equipment, boards, pipes, or wood piles that rodents can use for hiding or nesting. When storing wood or other materials, ensure that they are elevated at least 6 inches above the ground.

Rodent Proofing

The most effective and permanent rodent control is to keep rodents out of buildings. Doors, windows, screens, and cracked concrete are all areas where rodents can gain easy access. Be aware of openings near the top of buildings as well. Roof vents, eaves, attic vents, overhangs, and roof top air conditioning units provide access. Down spouts need a screen on the bottom as well as the top.

Baiting and Trapping

A successful rodent control program will combine the elements of baiting and trapping to achieve the highest rate of success. With any rodenticide, bait acceptance is the key to good control.

Exterior Baiting

  • Set up a perimeter baiting program using tamper resistant bait stations.
  • Place stations every 30 to 50 feet around the perimeter of the building.
  • Maintain a fresh, uninterrupted supply of bait.

Interior Baiting

Use a versatile bait station (one that can be re-located) along walls, in corners, under pallets, appliances, and other tight areas.

Places stations every 15-30 feet for rats and every 8-12 feet for mice. The use of bait stations in which the bait is secured inside the station is recommended for the following reasons:

  • People and wildlife might shake bait out of the bait station.
  • Rodents can move or kick bait into the station entryways, making it accessible to a reaching hand or a pet's paw.
  • Secured bait provides added bait protection in sensitive areas, such as around children or pets.


Non-poisonous Trapper Glue Boards are a useful tool for monitoring and capturing rodents. The effective use of glue boards depends on the correct placement of the boards. Identify rodent runways and harborage, place the boards directly in the runway, flush against the wall between the rodents' harborage and feeding areas.

What We Do

The Vector Control Division is responsible for rodent control on city property. Vector Control actively works to prevent rodent infestations on city property using a variety of methods. Rodent prevention measures include removing rat harborage and food sources, placing rodent bait stations, snap traps, and glue boards.

The Bureau of Environmental Health addresses rodent concerns on private property.

If you have concerns about rodents, please contact us at (757) 664-6510 or online.