Don't heave your hot dog remains into the bushes after a backyard barbecue. Don't leave the trash uncovered. And whatever you do, don't feed the dog on the porch unless you're certain every last kibble is gone before you go inside.

Exterminators and rodent experts say a mild winter and construction in the valley have birthed an abundance of rats this season — and residents trying to mimic the overgrown country garden look of Sunset magazine may be contributing to the problem.

DNews graphicFacts about ratsRequires Adobe Acrobat.

"They are overpopulated this year big time," said Ron Douglas, owner of Critter Control, a pest extermination company specializing in bats, raccoons, moles, skunks, rats and squirrels. "It doesn't help that people want to set up their backyards like a nature walk."

One Holladay man moving dirt from an old compost pile found a rat nest full of a dozen squirming rat babies.

Another long-tailed rodent used a dryer vent to bust into the basement of a home in West Valley City, then chewed through the plastic mattress of a water bed.

Visitors have complained about seeing rats at Layton Commons Park, where the ideal combination of duck food and pond water are a premier rat attraction.

Local health agencies say there have been no recent cases of rat-transmitted disease, but all report an increase in rat complaint calls this summer.

"Environmental conditions this year have been perfect for rodents," said Gary Cook, an urban wildlife specialist with the U.S. Department of Agriculture. A mild winter meant fewer rodents hibernated, so more bred all year. The annual winter "kill off" also didn't happen.

Now it's hot and dry outside, and Cook's calls are coming from people who live in areas with canals, irrigation systems, streams or other water sources. Local water sources for rats are drying up, so they are migrating to water. "People are seeing them a lot more because of that."

"There are definitely more because of the wimpy winter and all the housing construction going on," said Douglas, who has answered many rat calls from new housing subdivisions with open fields next door. "And they're definitely getting into housing."

"I'm not going to say they're widespread, but they are definitely there if you look for them," said Craig Weinheimer, an inspector with the Salt Lake Valley Health Department. "And once you've positively identified one, you tend to see them wherever you look."

Utah has kangaroo rats and desert rats, but the rodents most disconcerting are the Norway rats — Rattus norvegicus — the brownish gray mammals with a pointy nose and a long, "ratty" tail, according to Rachel Jolley of the Utah Division of Wildlife.

Rats live in colonies, usually one male to a few females and a hoard of babies. While mice will travel only 10 yards or so for food, rats will shuffle 150 to 200 feet sniffing out food or water. They can chew through almost any substance, including concrete, wood and leather, and they can cause extensive damage to wiring systems if they gnaw their way into a home.

From Sandy to Magna and into the Avenues, rats have been sighted in fields, businesses and high-end neighborhoods.

"We're getting a lot of calls about rodents in general," said Eric Olsen of Wasatch Exterminators. This has been a great harvest season for fruit, but that means more rats, mice and insects, too, he said.

What a difference a little fur on the tail makes, says Diane Keay, environmental health supervisor for the Salt Lake Valley Health Department. "You see something with a naked tail and nobody likes it, but you put something out there with a furry tail like a gerbil and everyone likes it."

In some cases, people may unknowingly bring on their own rat problems.

"This lady is telling me, 'I don't know why I have rats,' " Critter Control's Douglas jokes. "She's got 10 bird feeders and a pile of wood as big as a car and I'm telling her, 'That's their condo, and those are their restaurants right over there.' "

Bird feed. Dog food. Ornamental ponds and leaky sprinkler systems can all beckon a rat. "The stereotype is, it has to be a slum with garbage all around," he said. "That's not true."

Correct those problems, health officials say, or buy one of myriad rat traps, baits or poisons.

"And importantly, people should leave rodents alone," Keay said. "People should never stick their hands down a rodent hole." Rats are carriers for a number of diseases, but they don't carry rabies.

Rampant rat populations have been reported throughout the country this summer.

New York City Mayor Rudy Giuliani proposed a rat task force after people spotted some at Gracie Mansion. In Fort Worth, Texas, a couple driving to a mall spotted a "wave" of rats in a field earlier this month, according to an article in the Forth Worth Star-Telegram.

Steve Westover, general manager of Steve Regan Farm Supplies, is selling many more baits, traps and poisons. "But you do have to view rats and mice like any other pest in the yard . . . like a snail in your garden or an aphid on the rose bush."

But rats?

Westover agrees: People really freak out about rats.

"There's more folklore to them," he said. "And they're bigger."

E-MAIL: lucy@desnews.com