Some of the most irritating house pests are mice and rats, which are species of rodents. Homeowners cringe at the thought of having these animals taking up residence in their homes.

I had to deal with this problem with a duplex I was renting back in the 1990s, so I can relate to those whose homes are being invaded. Although these animals have differences, they cause similar problems. Rats and mice can spread diseases, contaminate food and cause structural damage by gnawing, which can also cause fires if they chew on electrical wires.

What should you do if you have a problem with these animals? What are the best methods of keeping them out of your home?

The three main types of rodents that infest homes are the Norway rat, roof rat and the house mouse. The Norway rat is the largest. It has a thick and heavy body that can grow seven to ten inches in length. The animal is gray to brown with the underside gray to white. They burrow extensively in soil and prefer to nest in basements and crawl spaces.

Roof rats are smaller, with six to eight-inch bodies. They are black to brown with a lighter colored underside. Roof rats do not burrow much. They enter and build nests in the upper portion of homes, such as attics. The house mouse has a small and pear-shaped body two to three inches in length with a gray to brown color. They are excellent climbers and can infest both upper and lower parts of structures. Since they are small in size, they can gain entry into the home more easily than rats. Consequently, mouse infestations are more common than rats.

How do you know if rats and mice are infesting your home? Frequently, their droppings can be observed in the areas they infest. Sometimes a musky odor is present. They will form paths between feeding and nesting sites, which are referred to as runways. The animals use these paths continually and prefer to move along objects such as walls. Another sign is gnawed marks. New ones are light in color, and they will darken over time.

Keeping the rodents out of your home in the first place is the best preventative measure. They can enter through small openings and can gnaw through wood, lead, aluminum, and other materials. Rats can squeeze through gaps that are a one-half inch in width, and mice can enter smaller ones. They can also enlarge openings that are too small by gnawing. Several measures can be taken to exclude them. Seal openings in walls with materials that are resistant to the rodent’s gnawing such as small mesh hardwood cloth, galvanized steel or concrete. Plug holes with steel wool or copper mesh before sealing. Make sure any gaps under the siding at the top of the foundation are closed. Seal up openings around pipes and electrical conduits where they enter exterior walls. Keep doors to the outside closed when not in use, and install weather stripping around doors and windows to allow for a tight fit when closed. Cover air vents with a one-quarter inch hardwood cloth, and make sure dryer vent flaps work correctly.

Practicing proper sanitation, which eliminates places that provide rodents with food, water, and shelter, will help reduce their populations. Remove any debris next to the foundation, such as log piles, brick or stone piles, accumulations of leaves and other debris.

Prune any plant material 12 inches away from the foundation, and also pull back the mulch from the same distance. Clean any food or drinks that have been spilled and keep all food material in sealed containers or the refrigerator. Do not leave pet food out overnight as this will be attractive to rodents and other wild animals. Also, keep any bird feeders far away from the house as possible.

Once you have determined they are infesting your home, several methods of control can be utilized. Poison baits are effective in reducing rodent populations. They consist of a poison that is disguised as food material. The rodents consume it and will perish in a couple of days.

The active ingredients of the baits are at small levels and reduce the chances of the rodents avoiding it due to taste. The main drawback to them is that the rodents often die in inaccessible places, which may cause a foul odor. As with all pesticides, make sure you follow all label directions and safety precautions when using baits.

Snap traps are commonly used for control. Rats need larger ones than mice. Several foods can be used as baits, but peanut butter is the preferred choice. The traditional wooden traps are commonly used and the least expensive, but the newer plastic, single-kill mouse traps are much easier to set and clean.

The traps should be placed in their runways, such as along walls. Trapping is advantageous in that, unlike baits, they are not toxic and allows for the disposal of dead rodents, thus reducing the likelihood of odors from dead ones. If these methods do not get rid of the rodent problems, you should contract pest control professionals.

An infestation of rats or mice can be disturbing to the homeowner. However, employing a combination of preventative measures and using the proper controls will help bring the problem under control.

Timothy Daly is an Agricultural and Natural Resource Extension Agent with UGA Extension Gwinnett. He can be contacted at 678-377-4011 or

tdaly@uga.edu.