Rodent Control

There are many species of rodents. Most of them live outside and seldom present a problem for humans, while others (such as squirrels and groundhogs) are considered "nuisance wildlife" rather than "pests." The rodents most commonly encountered as structural pests and handled by exterminators in Pennsylvania are Norway rats and house mice, which together are known as "commensal rodents." (The word "commensal" literally means that they "eat at the same table" as we do.)

Mice

There are several species of mice in Pennsylvania, but the mouse most commonly encountered as a pest of homes and other buildings is the common house mouse. Other species, such as the deer mouse and the field mouse, are also encountered inside buildings from time to time.

Although dismissed by many as unimportant (and considered "cute" by others), mice are serious pests. Mice are involved in the transmission of several serious diseases including hanta, murine typhus, Lyme disease, ehrlichiosis, and many others. Because of their small size and largely uncalcified skeletal systems, they can squeeze through openings as narrow as a pencil, which enabled them to live in close proximity to humans and to contaminate food, cooking surfaces, and utensils. Mice also cause countless fires and communications outages every year when they chew through electrical and communications wiring.

Mouse Control

Effective mouse control consists of identifying mouse travel paths (or "runways"), placing baits and/or traps to reduce mouse populations, and (where practicable) using exclusion to keep them out of sensitive areas of buildings. In seldom-used buildings such as cabins that are unattended most of the time, multiple-catch mousetraps are often a good choice. In some cases, an insect treatment should be applied as the rodent population is eliminated to prevent displaced parasites from seeking new hosts.

Rats

The rat most often encountered as a structural pest in Pennsylvania is the Norway Rat, which holds the dubious distinction of being one of the first pests to be scientifically linked to the spread of disease. In 1898, the French scientist Paul-Louis Simond conclusively established the connection between rats, fleas, and the plague outbreak commonly known as the "Third Pandemic" of 1855 - 1899. (The causative bacterium, now known as Yersinia pestis, had been identified by the French bacteriologist Alexander Yersin in 1894.)

Rats are still a major public health threat even today. In addition to plague, rats are involved in the transmission of cryptosporidiosis, Lyme disease, hanta, rat-bite fever, and a host of other illnesses carried by their parasites. Rats also cause structural damage and cause fires by their gnawing, and can inflict painful bites.

Rat Control

Effective rat control control consists of identifying the rats' nests (which may be inside or outside), runways, and access points, baiting or trapping to reduce rat populations, and (when practical) sealing them out of sensitive areas (known as rat exclusion). In some cases, ongoing treatment may be needed to maintain a rat-free zone. Insect treatments may also be needed to prevent displaced parasites from migrating to new hosts.