If you have rats in your attic, they’re probably roof rats. These rats, which are also known as black rats, enter your home through broken drains or through toilets. They’re good climbers and can find their way in by climbing wires or branches that are touching your house. They may also gnaw their way in. Rats belong to the Muridae family of rodents, which contains one-quarter of all the mammal species in the world. Fortunately, there are several ways to tell if they’ve invaded your home.
Roof rats like to bring food back to the attic or hide it in thick vegetation outside of your house. Look for caches of food, including citrus fruits such as oranges, which they’re especially fond of. They also eat dates, berries, snails, garbage and birdseed. If you have a birdfeeder, examine it for rat droppings. Look for hollowed-out rinds hanging from a branch after a rat has extracted the fruit growing on a tree. Rats eat fruit from ornamental trees inside your house as well as from trees outside.
Look for rat droppings and urine in stored food that rats have been feeding on. Examine food packages for signs of chewing. Look for large tooth marks on wooden structures such as doors and ledges where they gnaw. Check wall and ceiling insulation for torn insulation, which rats use as nesting material. Examine electrical wiring in your attic for signs of damage caused by chewing rats.
Hearing sounds in the attic at night is often one of the first signs that you have rats. Rats like to come out at night to forage for food. Look for smudge marks on the surface of rafters, where roof rats climb. These marks are caused by oil and dirt rubbing off the rat’s fur as it’s moving around. You may not see droppings, because roof rats like to live above false ceilings and other overhead locations, but the appearance of black, banana-shaped droppings approximately 1/4 to 1/2 inch long is indication of rats. Look for droppings in recycling bins or around pet food dishes and storage containers. Rats may leave your attic in the evening to look for food outdoors. See if you spot them walking along a fence top or utility line at dusk. If your dog or cat brings home dead rats, or if you’ve found a rat drowned in your swimming pool or hot tub, you may have rats inside your house, as well.
In addition to spoiling food, rats spread diseases like typhus, leptospirosis, food poisoning and ratbite fever, and they can spread plague. Traps and poisoned baits can provide short-term control of rats but, to eliminate them from your home permanently, you need to rat-proof your home. Thinning vegetation around your house and removing overhanging tree limbs will make it less attractive to roof rats. Make sure all garbage containers have tight-fitting lids. Seal cracks and openings around water pipes, electric wires, drain spouts and sewer pipes. Rats and mice can squeeze through holes only 1/4 inch wide. Since roof rats can chew through plastic, wood and caulking, use coarse steel wool or wire screen to plug holes. Don’t forget to seal access points in the roof, as well.
- University of California Statewide Integrated Pest Management Program; Rats; September 2011
- Urban Wildlife Control: Rat Pest Control FAQ's in Atlanta, GA
- University of Arizona Cooperative Extension: Roof Rat Control Around Homes And Other Structures
- University of California Museum of Paleontology: Introduction to the Rodentia
- Photo Credit NA/AbleStock.com/Getty Images