As the illustrations show, the Norway rat is a larger, more stocky rodent than the roof rat. The tail of the Norway rat is shorter, whereas the roof rat's tail is longer than its body.

Though Norway rats, roof rats and house mice are omnivorous, the roof rat may tend to favor fruits, nuts and vegetables.

The city commensal (living with man) rat and mouse are little different from their country cousins except that, like man, they have adapted to the "asphalt jungle". Norway rats and house mice are distributed throughout the United States. Roof rats are primarily found in warmer, coastal areas.

City rats and mice may encounter more physical barriers to movement than do country rodents. While streets, railroad tracks, and bridges are not complete physical barriers, studies have shown that the "home range" of a rat rarely crosses these obstructions.

The home range of rodents is simply the normal limits of their movements. The home range generally contains food, water, and shelter Rodents will usually leave this area only under stress. For mice, this distance is as little as 10 - 20 feet, and for rats as little as 50 - 100 feet. Since over 80 percent of each individual rodent's movements will normally be within these distances, control efforts must be spaced so that individual home ranges are encountered.

Therefore, typical use directions on toxic rodent baits may state placement at 30-foot intervals. Otherwise, the rodent may have everything he needs close at hand and won't travel to where the bait is placed.

Rodents in cities are extremely used to human odor and activity. Just the presence of people or the cleanup of an area will not necessarily disturb many rodents, without some killing or removal techniques. Rodents have few natural enemies. Dogs and cats may kill the occasional rat or mouse, but these pets cannot keep a rodent population under control. It is up to the main enemy of pest rodents—people—to control these pests.

Unwanted rodents can be more than a nuisance; they can inflict serious injury through bites and the transmission of disease. They also steal our food, damage commodities, and weaken structures. Unchecked, their population will continue to grow at an alarming rate. Any rat in the urban environment is one rat too many!