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Rat and Mouse Control

There are many species of rodents, but only a few of them are common pests here in Ohio.

Norway rats (also called "brown rats" or "sewer rats") and house mice are the two rodents most commonly encountered as pests in Dayton and throughout the Miami Valley. Along with roof rats (which are rarely encountered in Ohio), they belong to a group known as "commensal rodents" because they "eat at the same table" as humans do, having adapted to eating our stored food and leftovers.

Both rats and mice are important public health pests because of their ability to vector serious diseases. They also cause many millions of dollars of economic damage every year from consumption and contamination of food intended for humans, pets, and livestock. They also damage stored property by their urinating, defecating, and incessant gnawing activity; and they create a risk of fires when they gnaw on electrical wiring.

Let's take a look at the rats and mice common to Ohio's Miami Valley and discuss why they have been considered pests from ancient times.

Norway Rats

A Norway rat facing the camera.

Norway rats (Rattus norvegicus) are also known as "brown rats," "wharf rats," "sewer rats," and "water rats." They're usually brown to gray in color, but variations are common, including jet black, pure white (albino), and tawny-colored individuals. They're fairly stocky animals as rodents go, with blunt noses and shaggy hair. Their bodies average from seven to nine inches in length as adults, and their tails from six to eight inches in length.

Norway rats also have the dubious distinction of being among the most notorious disease vectors in history. Awareness that rats were in some way associated with disease dates back at least to biblical times, and possibly even earlier. Rats are implicated in the transmission of plague, hantavirus, leptospirosis, lymphocytic choriomeningitis, rat-bite fever, and several other serious diseases. They also can transmit other disease organisms on their fur when they travel from places like sewers to human-occupied areas.

By nature, Norway rats are burrowers who build underground nests. It's not uncommon to find Norway rat burrows outside buildings that are well-sealed against rodents, but that have open dumpsters or trash bins outside. Around restaurants, rats often emerge from their burrows in nearby abandoned lots or other patches of earth to dumspter-dive for leftovers as soon as the restaurants close. They seem to be able to learn when the day's leftovers will be discarded, and emerge from their burrows on-schedule for their share of the buffet.

More commonly, however, rats look for nicer places to live than burrows, especially when winter is approaching. Ideally, they like places that are warm, secure from predators, and close to sources of food and water. Basements of homes and other buildings, barns, sheds, crawl spaces, sewers, or utility tunnels are considered primo real estate for rats; but they'll also make do with the spaces under buildings (such as underneath a slab foundation) if that's the best they can do.

Norway Rat Control

The effective control of Norway rats begins with non-chemical control, especially habitat modification. That means taking away the things they need to thrive, epsecially their food, water, and harborage (living spaces).

Because they've adapted to living on human leftovers, better waste management is often a part of rat control. Simple things like keeping dumpster areas clean and securing the lids on the garbage bins can go a long way toward fighting a rat problem. So can removing clutter that the rats live in during the warmer months.

If the rats are getting into a building, then obviously the building needs to be rat-proofed to keep them out. This may mean fixing holes, replacing missing bricks, installing door sweeps, and repairing basement windows. Basically, any opening that's big enough for a rat to squeeze through needs to be sealed.

Elimination or rat populations through trapping or the use of rodenticides is actually the third step in solving a rat problem. In most cases, traps are preferred because they're faster and avoid the possibility of a poisoned rat dying in a hard-to-reach area. But in some cases, such as when the rats are living in burrows outside the building, rodenticides are necessary.

House Mice

A house mouse in a corner amoung some wooden crates.

Because mice are smaller and "cuter" than rats, many people don't consider them as dangerous. That's a mistake. Mice carry many of the same diseases as rats do (and a few that they don't). Moreover, because they're smaller and less cautious than rats, mice actually come into much closer proximity to humans than rats do. It's not at all uncommon, for example, for mice to get into kitchen cabinets and drawers. Rats rarely get that close to humans.

In addition, mice have much smaller ranges than rats do. Most mice rarely travel more than 25 feet from their source of food. So a mouse that discovers the food in your kitchen cupboard may just decide to move into the kitchen wall right behind it so it doesn't have to travel so far to eat. If they're living there, chances are that they're also breeding there; and because mice are prolific breeders, a small mouse problem can quickly become a big one.

Mice are also curious creatures by nature. Although they don't travel far, they do explore extensively within their home ranges. That's why it's common to find mouse droppings in kitchen drawers where utensils are stored. There's nothing in there that's of any use to them. They just like to explore. Unfortunately, in doing so they spread disease-causing pathogens wherever they go. It's rare for a rat to walk across your kitchen counters, but mice do it all the time.

In short, from a health perspective, mice are every bit as dangerous as rats. Don't let their small size fool you. You definitely don't want mice in your home.

Mouse Control

Like rat control, mouse control also begins with habitat modification. This usually means storing foods in mouse-resistant containers rather than leaving it in its cardboard boxes, which mice can nibble through with ease. All human or pet food that's not in cans or jars (especially grain-based foods like pasta or cereal, dry beans, chocolate, and other plant-based foods) should be stored in mouse-resistant containers.

Tightly-sealed metal, glass, or Lucite canisters are good choices to make your food mouse-proof. Softer plastic containers will also suffice for a short time until the mouse problem is solved, but they're not a permanent solution. The mice will eventually gnaw their way through soft plastic. (Of course, once we get rid of the mice, you can use all the soft plastic containers you like.)

Because of their small size, mice are very difficult to seal out of a house. But every effort should be made to at least seal the most obvious openings. Adjusting the garage door so it closes tightly to the ground, installing door sweeps on all the doors, and sealing around pipes and wires where they enter the building, are all essential for effective mouse control. The gaps that the mice are using to get into the living area of the home should also be sealed. Often these are around moldings and pipe chases, especially in the kitchen.

Finally, the existing mice need to be dealt with. Trapping is the preferred way to eliminate a mouse population, but rodenticides may be needed in some situations. Sometimes it's just not practical to trap mice, for example, when the infestation is severe and the mice are traveling through the wall and ceiling voids. In those cases, careful application of rodenticides may be necessary.

Pro Zone Pest Control provides rat and mouse control to homeowners and landlords in Dayton, Springfield, Northern Cincinnati, and throughout Ohio's Miami Valley. Please contact us for more information about our rodent control services. We look forward to your call.