As with any city bordering a river, the City of Alexandria has a rodent population. To control the rodent population, Alexandria has several programs in place that operate on a daily, proactive basis throughout the City. These programs are administered by the Department of Code Administration. If you see any evidence of rodents please call the Department of Code Administration at 703-746-4200 or email the Maintenance Code Team to file a complaint.
Disease Transmission by Rats
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.
Physical Damage to Property
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 then they actually eat. Additionally, numerous fires have been started by rats chewing through electrical wiring.
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.
- Runways. These are frequently traveled paths along floors, stairs, and shelves, where droppings, rub marks and stains from rodent urine are found.
- 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.
Behavior of the Norway Rat
Norway Rats, as well as other rats, prefer food with a high carbohydrate and protein content although almost any type of food will be taken, food items in household garbage provides rats with a balanced diet.
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. Rat burrows start out usually short, varying between 12-30 inches in length. As the rats mature, begin to rear families, and the population grows, the burrows become enlarged and expanded.
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 not 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.
Behavior of the Roof Rat
Roof rats can be thought of as the "vegetarians" of the commensual rats as they prefer to eat seeds and plant foods such as fresh vegetables or fruits. The roof rat is appropriately named because by nature it is a climber and commonly lives above the ground in "roof" or aerial areas around structures.
The following proactive rodent abatement measures are requirements for construction, demolition, and land disturbance projects.
- According to the VA Code of Ordinances (Sec. 11-6-5) Whenever the code official notifies in writing the occupant of any building or premises that there is evidence of rat infestation of the building, the occupant shall immediately institute rat eradication measures and shall continuously maintain such measures in a satisfactory manner until the building or premises is rat-free or the code official advises that there is no evidence of rat infestation. Unless such measures are taken within five days after receipt of the notice, the occupant shall be punished accordingly.
- Upon receipt of written notice from the code official to the effect that there appears to be inadequate ratproofing or no ratproofing, the owner of any building specified therein shall take immediate steps to ratproof the building. The work and improvements necessary to ratproof the building shall be completed by the owner in time specified in the notice, which in no event shall be less than 15 days, or within the time to which a written extension may have been granted by the code official or the owner shall be punished accordingly. Compliance with this program should eliminate the rodents and prevent them from migrating to adjacent properties.
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.
- Consider sources of available water, such as ditches, stagnant pools, decorative fountains, and ponds. These are essential elements of a rodent's environment.
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 to wall voids and other areas in a structure. 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. Inert ingredients must appeal to a rodent's sense of taste and desire to gnaw. Start your baiting program by determining the severity of the infestation. Keep in mind that if rodents (particularly rats) are seen in the daylight then the problem could be quite severe.
- 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.
Use a versatile bait station (one that can be re-located ) along walls, in corners, under pallets, appliances, and other tight areas.
Place 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.
- Rodents can move the bait to their nest or other areas.
- Secured bait provides added bait protection in sensitive areas, such as around children or pets.
- Secured and elevated bait remains free of moisture that can collect on the floor of the bait station, thus prolonging it's useful life.
Non-poisonous Trapper Glue Boards are a useful tool for monitoring and capturing rodents. The effective use of glue boards depends primarily 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.
Factors that limit glue board effectiveness are dust, moisture on the rodent's foot pads and the boards become ineffective with age.
Rodent Control Program
The City of Alexandria has undertaken an intensive rodent abatement program. Rodents not only carry disease but also destroy property. To control the population, Alexandria has several programs in place that operate on a proactive basis throughout the city every day.
The Rodent Control Program is funded through the City's annual budget which provides funds for the baiting of sewers and other outdoor properties owned by the City.
There are three species of rodents which are of most concern:
- House Mouse, Mus musculus;
- Norway Rat, Rattus norvegicus; and
- Roof Rat, Rattus rattus
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. The potential reproductive capabilities of rodents are impressive, a female produces 4 to 7 pups per litter with a gestation period of about 19 days. If conditions are good, she is capable of giving birth every 24 - 28 days.
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 then the roof rat.
Roof rats are smaller and sleeker in appearance then 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. Theoretically, one female rat could have from 3 to 6 litters of 6 - 10 offspring per year. In other words, one adult female could be responsible for 320 million descendent within a period of three years.