How to Spot a Roof Rat Infestation and Keep Them Out

Few things are less welcome than a houseguest that never leaves, and roof rats fit that description perfectly. These small rodents, usually about six to eight inches long, resemble other rats but have a slimmer build, black or brown fur, a pointed snout, large ears, and a long, hairless tail. Unlike rats that stay closer to the ground, roof rats prefer elevated spaces such as attics, garage storage areas, rafters, roofs, and even the inside of walls.

So how can you tell whether roof rats have moved in? In an exclusive interview with Hunker, Ben Hottel, an entomologist at Orkin, explained the most common signs of an infestation, the best ways to remove these pests, and how to keep them from returning. He noted that they often use utility lines and tree branches as bridges into homes instead of crossing open ground.

There are also important health risks to consider. Hottel said roof rats and other rodents can carry several diseases, including rat-bite fever, which can spread through bites or contact with a dead rat, salmonellosis, which can come from food or water contaminated by rat feces, and leptospirosis, which may occur when rats contaminate stored food in a pantry. If you suspect an infestation, here are his expert recommendations.

Signs that roof rats may be living in your home

Hottel pointed to three major signs of a roof rat infestation. The first is droppings. Roof rat droppings are about half an inch long and have pointed ends. If you find them around the house, especially in an attic or rafters, it may be a sign of roof rats.

Another clue is grease marks. According to Hottel, unexplained greasy streaks on surfaces can indicate roof rats, since oils from their fur leave marks as they move along baseboards and other surfaces. If those marks appear, it is worth checking for droppings as well. The most obvious warning sign is seeing the rats themselves. Even one sighting, whether the rat is alive or dead, should not be ignored. Hottel said that if roof rats are visible in the home, it often means other rodents are also hiding nearby.

If you start looking for nests, check the attic, loft, or inside the walls. Hottel explained that roof rats prefer sheltered indoor spaces and often build nests from shredded materials such as paper, cloth, and cardboard.

How to remove roof rats and prevent them from coming back

Once a roof rat problem has been identified, the next step is to act quickly. As with any rodent issue, Hottel said calling a professional pest control company is essential. A serious infestation should not be taken lightly, and trained professionals can develop a targeted plan to eliminate it effectively.

Homeowners can also take preventive steps to reduce the chance of roof rats getting in. Sealing entry points is one of the most important measures, since these rodents do not need much room to squeeze through. Hottel said roof rats can fit through holes as small as a quarter. Gaps around exterior doors should be sealed, and utility line access points should be properly closed off. Installing screens on vents can also help, although Hottel warned that this work can be dangerous for people without training and may be best left to professionals.

Another useful step is trimming back tree branches. Because roof rats use branches as routes into homes, cutting them away can make access more difficult. Finally, remove food sources by securing garbage bins, cleaning up fallen fruit or nuts, and making sure home compost is rodent-proof. These steps can help keep roof rats out of the yard and away from the house.