Few pests generate as many persistent myths as do pest rodents and their management. Who hasn’t heard stories about “rats as big as cats,” and how some rodenticides supposedly make rodents go outside to drink, or perhaps allegedly mummify them? Here are some great rodent myths:
MYTH: SEWER RATS ARE DIFFERENT FROM WHARF RATS.
FACT: The common commensal rat goes by many nicknames, such as house, wharf, barn, sewer or brown rat. But the correct common name for Rattus norvegicus is the Norway rat. The name supposedly is derived from the fact that the first named specimens were from Norway. Actually, these animals originated in central Asia and spread throughout the world by exploration, commerce and settlement.
The other common commensal pest rat in the United States and many other countries is the roof rat, R. rattus. It’s also called the black, plague or ship rat. This rat is smaller than the Norway rat and is found in warmer areas, such as in California, Texas and Florida. Cotton rats (Sigmodon spp.) are between rats and mice in size. This native species can be especially common around homes in Southeastern and South-Central United States.
The wood rat or pack rat, Neotoma spp., can be common around homes in the Southwestern states. Many native rodents might invade structures, such as taking insulation from crawlspaces for nesting material.
MYTH: RATS CAN GET AS BIG AS CATS.
FACT: The common wild Norway rat rarely reaches 1 pound. A few examples approaching 2 pounds have been recorded in captivity, but these rats become older and heavier than would likely occur in the wild.
A big Norway rat has a body about 8 inches long, with a tail nearly as long. Some so-called “rat” sightings in rural areas or along rivers and streams may have been other animals, such as muskrats.
MYTH: THE MICE THAT PEOPLE COMPLAIN ABOUT ARE ALL THE SAME SPECIES.
FACT: The common house mouse, Mus musculus, is present throughout the United States and is the most common commensal mouse pest to be found in and around structures.
But don’t assume the pest in your house is necessarily a house mouse. Native rodents such as deer mice and voles also can be seen in and around homes. Shrews also can be common and are not even rodents, but insectivores.
Most rodenticides are only labeled for control of Norway rats, roof rats and house mice. Don’t create an off-label product use situation by failure to identify the rodent species before designing your control efforts.
MYTH: RATS AND MICE ARE NOCTURNAL (ONLY ACTIVE AT NIGHT).
FACT: Rats and mice are more active when there is less danger about, which in many cases is at night. But they can dart about during daylight hours as well to secure food and shelter, especially if they have learned there are routes they can take and areas they can go where they will not be challenged. In some environments, such as nightclubs and theaters, rodents may take advantage of the fact that there is less human activity during the day.
Also, consider that rats and mice live in social groups where dominant animals may defend the best shelter, food areas and potential mates. Less-dominant individuals might be forced to be active at more-dangerous times, such as during the day. Regardless of the time, their eyes and ears are always alert to the slightest sounds or movements.
MYTH: IF YOU SEE RATS OR MICE IN THE DAYTIME, THERE MUST BE A LARGE POPULATION AROUND.
FACT: Individual rats and mice sleep only for short periods and might move about at any time of the day or night. They are more visible during the daytime, and so even small populations may give themselves away by sightings when people are up or businesses are open.
Rats and mice normally will move and forage about in the open much more extensively at night, but sightings are not a good indicator of how many rats or mice are living nearby.
A better indication is the amount of signs in the area, such as burrows, droppings and damage.