Rats and Their Control

Rats have a special place in the hearts of pest control professionals because they were the first animal to be professionally controlled. The first exterminators were known as "rat catchers," and the profession came of age in earnest once people started understanding the connection between rats and transmission of Yersinia Pestis, or bubonic plague, in the 1300's.

Of course, people back then didn't fully understand the biology, but they did know that the more rats there were, the more likely people were to get sick with plague. Nowadays, with the benefit of modern science, we know that fleas were actually the obligate vectors. Rats (and some other animals, like mice) were merely reservoirs for the bacteria. Nonetheless, all modern-day pest management professionals can trace our heritage back to the rat catchers who pioneered the professions of pest control and environmental sanitation.

Rats are still among the most important public health pests here in California, in particular two species: the Roof Rat (Rattus rattus), and the Norway Rat* (Rattus norvegicus).

 

Roof Rats

Close-up of Rattus rattus, commonly known as the roof rat, on a painted wooden porch floor.

Roof rats are also called "black rats," but they can be brown or black in color, often with some gray mixed in. They're sleek and agile with pointy noses and big ears. Their tails are at least as long as their bodies and heads (usually longer), and the average length of a roof rat from nose to the end of the tail is about 13 to 18 inches.

The reason we call R. rattus "roof rats" is because they're commonly found in roofs and attics. In nature, they're aerialists, not unlike gray squirrels. That's why they have slender, graceful bodies and excellent balance. They're comfortable in high places and can easily run along tree branches and power lines to get into buildings.

Roof rats are also less associated with filth than Norway rats are. Roof rats really don't need humans or our garbage. Although they'll feed from a trash can or dumpster if it's convenient, they can live quite comfortably on plants, seeds, and nuts that they find in nature.

The thing about roof rats that attracts them to humans is our buildings. Although they usually live in trees in nature, they'll quite happily move into the attic of a building if they can get inside. Once they're inside a nice, cozy attic where they can can relax a bit and not worry about being eaten by predators, they make themselves at home, which includes reproducing rapidly. Populations of roof rats can reach several dozen in a house, or hundreds in a warehouse or other large building.

Roof rats can cause great damage to buildings through their gnawing, especially when they gnaw on electrical wires, which causes many fires every year. They also damage mechanical equipment, ductwork, and household items or clothing stored in the attic with their gnawing, droppings, and urine.

In addition to the damage, roof rats create a serious health hazard from their urine, droppings, and parasites. If the attic contains heating or air-conditioning equipment, it may distribute pathogens throughout the house. They can also cause odors that are very difficult to remove.

 

Norway Rats

A Norway rat, Rattus norvegicus, in an outside flower box.

Norway rats are also called wharf rats, brown rats, and sewer rats, and they're about as different from roof rats as they could be.

Norway rats are bigger and stockier than roof rats, with heavier tails that are shorter than their bodies and heads combined, blunter noses, and smaller ears. Their bodies are usually from seven to 10 inches in length, and their total length from their noses to the ends of their tails can range from 13 to 20 inches. They are predominantly brown or gray in color, but variations are common.

Although not graceful climbers, Norway rats can climb well enough if they need to. They also have good balance and can run along pipes if need be, but they're more comfortable on the ground. They're burrowing animals by nature, and although they'll happily move into homes and other buildings if given the opportunity, they usually stay in the basement and lower floors unless population pressures push them upwards or they are attracted upstairs by food.

Norway rats are excellent swimmers and can easily make their way through a town or city by swimming in the sewer pipes. Occasionally they make their way up into an occupied building and emerge through a toilet or a drain without a secured screen.

Unlike roof rats, Norway rats are much more dependent on humans for their food. They've evolved in such a way that human garbage has become their primary food source. They routinely feed from dumpsters and trash cans, even gnawing their way through plastic garbage cans if need be to get to the goodies inside.

Norway rats can cause serious damage inside a building by their gnawing. They can also easily travel through walls and ceiling to get around, usually to find food. Like roof rats, their gnawing on electrical wiring can cause fires. They also cause serious disease risk by their droppings, urine, and shed parasites. Occasionally they get into occupied areas of a house, and they will bite if they are cornered or threatened.

 

Rat Control

Bust-A-Bug provides rat control in Brentwood, Contra Costa County, and throughout most of the Bay Area. The control methods differ according to the situation, but typically include a thorough inspection, trapping, and the use of rodenticides. We provide rat control for both residential and commercial accounts, as well as wide-area rat control (for example, for condominium communities).

Exclusion, or "rat-proofing," is provided to our customers upon request. It includes a visual inspection of the house, foundation and neighboring fences and trees. It can help reduce rat activity for the long term and it is highly recommended. Not all homes will be capable of being rat proofed, so an inspection will let us know what can be done. If a rodent roof inspection is desired, please mention it. We charge a flat rate of $150 for roof inspections. Once the inspection is finished a verbal and/or written report is provided to our customers with what needs to be fixed. For side doors to the garage or garage doors that require fixing or weather stripping we recommend hiring a handyman who can do the work properly. Other smaller holes can be fixed by our tech for a small fee.

Another thing that is almost always necessary to effectively control rats (especially Norway rats) is habitat modification. This basically means making your property less attractive and accessible to rodents. This can include things like exclusion (sealing the rats out) and removing harborage areas. It also means denying the rats food, which can mean using better methods of disposing of garbage, removing pet feeding dishes when the pets aren't eating, and storing human and pet foods in rodent-resistant containers.

Fortunately, at Bust-A-Bug Pest Management, we provide a thorough inspection to help you make your home or business less attractive to rodents for maximum control of roof rats and Norway rats. Please, contact us for more information about how we can help you eliminate your rat problem.

 

* Both the taxonomic and common names of Rattus norvegicus were based on the mistaken belief that the species originated in Norway. We apologize for any perceived insensitivity.