When Nancy McDonald found roof rats in her attic last winter, she says she "freaked out."

The Lutz homeowner promptly called highly rated Rick Ricker Termite & Pest Control Inc. in Odessa. Three months later, she says, the last rat had been trapped and they haven't come back.

"Some people say they don't hurt anything, but you know what, I didn't want them up there," McDonald says. "I was not happy with them up there."

Natural climbers

Roof rats - also called black, fruit or citrus rats - are one of the top household pests in Florida, according to Bill Kern, associate professor of entomology and nematology with the University of Florida.

They're called roof rats because they are natural climbers and prefer to nest in trees or attics. They chew on wires, ducts and insulation. In the United States, they are found mainly in the Gulf Coast states and California.

One female can produce 40 offspring a year, and those babies can produce their own litters within four months.

Ricker says roof rats can move into a home undetected, particularly if the attic is well insulated so the homeowner can't hear them. He likens them to squirrels in that they do their foraging outside.

"They get brazen when they overpopulate," he says, adding that one customer had a roof rat nesting on the cover of his Harley-Davidson.

Wait for a professional

Getting rid of them requires sealing all access points, removing food and nesting areas, and trapping the remaining rodents. Exterminators have their own preferences regarding the proper order. Some trap, then seal. Others seal, then trap.

Dan Soles, owner of highly rated Soles Exterminating in Seminole, does the latter. "The rule of thumb is any hole one-half inch in diameter," he says. "If they can squeeze their head through, they can squeeze their bodies through."

The No. 1 access point in most slab homes is the Freon line that runs from the air conditioner compressor on the ground up the exterior wall and into the attic, says Mike Ahles, environmental control technician with the St. Petersburg Sanitation Department, which offers free rat control to residents.

Once the building is sealed, Soles sets traps instead of using bait inside. Ricker agrees with that approach. With bait, "You will wind up with a dead rat and you won't be able to find it," he says.

Although homeowners' first impulse is to clean when they find rats, Ahles prefers they keep everything the same, capture as many rats as possible, then clean. "If you disrupt everything, it is going to scatter them," he says.

Costs vary widely. McDonald's rat abatement was covered under her $360 annual pest control contract. Soles says he charges about $95 for a basic job.