Rodents

When the health department receives a complaint about rats and/or rat-breeding conditions on a property, a Pre-Inspection Notice (PIN) is sent to the responsible party, asking for the conditions to be corrected. If the responsible party does not comply by the deadline stated in the letter, the property is inspected by the Housing and Community Environment Program. If the inspector observes evidence of rodent activity on the property, they will cite the responsible party and send a Notice of Violation (NOV) and a copy of the inspection report in the mail. The NOV gives them a specific amount of time to take care of the problem. If the property fails a second inspection, the owner will receive a warning letter that may result in a required appearance in Magistrate’s court and/or fines.

Once the environmental and sanitary conditions on the property are cleaned up, residents are obligated to control the rats. Excellent “do it yourself” rat control products are sold in local hardware stores. As long as the “directions for use” on the product label are carefully followed, the rats may be gone in a month. Commercial pest control companies also provide rat control services. Licensed pest control contractors are able to use a wide variety of rat control products, some of which are restricted-use pesticides not available to residents.

Rat problems are often a shared neighborhood problem. One way to converse with neighbors about rats is to share the Health Department’s pamphlet, Resident’s Guide to Rodent Control(PDF, 458KB). If there are conditions that cause rats to remain on neighboring properties, like improper garbage storage or dog feces that is not regularly picked up, a complaint can be submitted by calling the Housing and Community Environment Program at 412-350-4046, by filling out our online complaint form, or by contacting your local municipal government. If evidence suggests that the source of the rat problem is the common sewer, more information is available in the document, How Rats Enter Homes from Sewers(PDF, 455KB). Printed copies of these materials can be requested from the Housing and Community Environment Program.

If you live in your own home without tenants, state law allows you to purchase and place rodent bait on your own property. As long as the “directions for use” printed on the product label are carefully followed, all formulations of rat bait that are sold in hardware stores are safe and effective at killing rats.

However, owners of commercial and rental properties with four or more units must hire a commercial pest control company to service rodent and insect pest problems. Unless the landlord or a maintenance person is a certified pesticide applicator with the Pennsylvania Department of Agriculture, it is against state law for them to use pesticide in rental units/apartments. It is important to give advanced notice to tenants when you are planning to use pesticides and keep all records of treatments conducted.

The safest way to expose rats to a pesticide in the home and yard is to buy “tamper-proof bait stations” sold in hardware stores. Bait stations have large chunks of bait (called “bait blocks”) secured inside a strong plastic box. To prevent animals from removing the bait box, secure or anchor bait stations to the ground or fence post using stakes and wire. Place bait stations along the same route that rats normally travel — along building walls and fence lines. Rats are more likely to eat from stations set along pathways they normally travel.

Direct burrow baiting means placing rat bait directly into the rat burrow. This is a safe and effective delivery method. Always read and follow the manufacturer’s label, using the smallest amount of bait that will be effective. Use disposable gloves when handling bait and wash your hands afterwards.

A typical rat burrow is 2.5 to 3 inches in diameter, 6 to 8 feet in length, and only 6 to 8 inches deep. Fresh dirt “kick-out” can usually be seen at the entrance. However, bagged bait should not be used in burrows. Rats may push the bag out of the burrow where children, pets or wildlife can get to them. Instead, place small amounts of loose or pellet-sized bait into burrows with a long-handled spoon or funnel. This will ensure that the bait is placed deep into the burrow where rats are more likely to eat it.

Provide a continuous supply of bait until feeding stops. Collect and dispose of any dead rodents found during the course of a rat control program. You can pick them up using a sturdy plastic bag inverted in your hand. Then, seal them in the bag and dispose of them with household garbage. Be sure to remove and properly dispose of all uneaten bait at the end of a control program.

Rats find harborage in and around your backyard and eventually take advantage of entry points into your home in search of food and shelter (see illustration below). Once rats get inside of a home, snap-type traps help reduce the chance of a bad odor caused by a poisoned rat that has died in an inaccessible location. However, rat traps take a lot of time and effort to achieve any measure of success. It is also important to find the points of entry and seal openings with rat-proof materials (see: Rodent-Proof Construction and Exclusion Methods from Internet Center for Wildlife Damage Management(PDF, 974KB)) such as steel wool, metal flashing, cement, etc.

Devices intended to frighten rodents away, such as high frequency and ultrasonic sounds, are generally ineffective for controlling rats in homes and gardens. Ultrasound has not been shown to drive established rodents out of buildings or cause above-normal mortality in their population. Ultrasound cannot be recommended as a solution to rodent problems.

Although house cats, some dogs, and other predators may kill rats, they do not effectively control a rat population under most circumstances. Rather, many rat problems around homes can be related to the keeping of pets. Rats are often found living in very close association with dogs and cats, and frequently live beneath a doghouse, feeding on the dog’s food and waste when it is absent or asleep.

There are some odors and tastes that may irritate rodents initially, but no repellents have ever been found to solve a rat problem for more than for a few days. As long as the environmental conditions that initially attracted and fed the rats are eliminated (garbage, pet food and waste, etc.), rat control with a pesticide is usually the most permanent and cost-effective method.

An exhaustive review of current rat control methods and materials is found at the University of California Integrated Pest Management Program.

If you have any questions about the products or information provided, please call the Housing and Community Environment Program at 412-350-4046.

These recommendations are provided only as a guide for managing rat problems in the home and yard. It is always the pesticide applicator's responsibility, by law, to read and follow all label directions for any pesticide being used. No endorsement is intended for products mentioned, nor is criticism meant for products not mentioned. The author and the Allegheny County Health Department assume no liability resulting from the use of these recommendations.

• Resident’s Guide to Rodent Control(PDF, 458KB) from Allegheny County Health Department
• How Rats Enter Homes from Sewers(PDF, 455KB) from Allegheny County Health Department
• Practical Guide to Rodent Control(PDF, 2MB) from Los Angeles County Department of Public Health
• Rodent-Proof Construction and Exclusion Methods(PDF, 974KB) from Internet Center for Wildlife Damage Management
• Burrow Baiting Guide(PDF, 914KB)
• Review of Rat Control Methods from University of California Integrated Pest Management Program
• Rodent Information from the Centers for Disease Control