Residential Pest Control: Norway Rat vs. Deer Mouse

Safe and effective residential pest control involves thoroughly understanding a pest’s biology and behavior. Applying blanket pesticides is no longer a viable method for controlling an infestation, which means your local pest control company must formulate a more strategic and multi-pronged plan of action. The first step toward doing this is, of course, to accurately identify the pests in question – this is especially true for rodent pest controlHigh-five sitting wild deer mice isolated on white.

As homeowners, it’s tempting to lump mice and rats into the same category when it comes to residential pest control. After all, they’re both rodents, they both carry diseases, and to say they’re both an undesirable presence in the household is generally an understatement. Both have also been a problem for centuries, mainly due to their incredible ability to survive and reproduce.

However, rodent pest control experts must differentiate between mouse control and rat control, because the tactics and approaches required for each can differ. That’s why, when a homeowner detects an infestation it’s important to consult a local pest control company to accurately identify the pests before any action is taken.

Two rodents that are often mistaken for each other are the deer mouse and the Norway rat. Both are commonly found in the Pacific Northwest, and they share some similar habits. Both will gnaw at paper, books, wood or upholstery to use for nest material. They will also chew plastic, cinder blocks, wiring and soft metals such as lead and aluminum – creating potential fire hazards. Like any other rodent, they are attracted to food sources within a home, can contaminate said food sources with their urine and excrement, and are harbingers of many nasty diseases. So when rodent pest control is required, how’s a homeowner to tell whether the culprit is a deer mouse or the Norway rat?

The following is a look at what differentiates these two pests, as well as how to identify an infestation.

About Deer Mice

Deer mice, or peromyscus, are native to North America and differ from their fellow mice in several key ways. For starters, they have larger eyes than the common house mouse and can reach 5-8 inches in length, which is why they’re easily mistaken for rats. They often have two-toned coloring, with a white underside and darker colors covering the back. Deer mice are also faster runners and jumpers than regular house mice – hence the name, which was coined in 1833. Like other mice, they can squeeze through holes as small as a nickel; sealing up holes in your home large enough for these critters to crawl through is an important component of mouse control.

About Norway Rats

Norway rats are one of the two main species of rats (along with the roof rat) that are typically found in the Pacific Northwest. They are larger than the roof rat, with the adults reaching 13-18.5 inches in length from head to tail. They are usually covered with coarse, brown hair and have whitish-gray bellies.

The Norway rat is not from Norway originally but is now believed to have come from Asia (most likely China). The English naturalist John Berkenhout, who wrote Outlines of the Natural History of Great Britain in 1769, gave the species its, rattus norvegicus, believing it migrated to England from Norwegian ships in 1728. He was wrong. Ironically, there were no Norwegian rats in Norway at that time.

So… Which One is It?

Although an adult Norway rat is roughly double the size of a deer mouse, an adolescent Norway rat will appear similar in size to an adult deer mouse, which is why telling the two species apart at a glance can be tricky. Your local pest control company will identify whether the critter infesting your home is a deer mouse or a Norway rat by collecting a specimen for analysis. The shape and size of the head relative to the body is a key distinguishing factor – the rat’s head will be short, stubby, broad and large relative to its body, whereas the mouse’s head will be triangular and small relative to its body. The deer mouse also has a sharper and narrower snout and larger ears than the Norway rat.

Even if you think you can identify the species yourself, it’s best to let a rodent pest control expert handle the infestation. Deer mice and Norway rats can be carriers of the dreaded Hanta virus, which can be transmitted through their urine, saliva and droppings. A person can be exposed to Hanta virus by disturbing or cleaning rodent droppings as well as by living or working in an infested setting and breathing in the contaminated dust. Because of this danger, your best bet is to call a residential pest control company for help.

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