Thursday, July 6, 2000; A1, A18

Ken Thomas holds a roof rat he trapped on his deck in southwest Santa Rosa. He was holding the rat for the Marin/Sonoma Mosquito and Vector Control District, which will test it for disease.

Rat problem spreads to county

Homeowners fear
disease-bearing pests

By MICHAEL COIT
Press Democrat Staff Writer
Photo by Mark Aronoff, Press Democrat

Slender rodents with long tails scurry across the back deck of Ken Thomas' home in broad daylight, a sure sign that the rat population is growing.
    Thomas trapped seven of the nocturnal pests in the past three days, including one in a cage trap provided by the county so the animal can be tested for disease.
    Yet Thomas, a west Santa Rosa resident, said he's fighting a losing battle.
    "The infestation is so bad," he said Wednesday. "The other day, there were two of them out there and one in the trap. At night you can see them run down the top of the fence."
    The North Bay's rat problem has spread from Marin County to Sonoma County, with roof rats joining the more familiar Norway rat as a growing nuisance.
    Sonoma County's top rat observer said trapping and whatever other controls homeowners and pest control professionals use seem to barely dent the population.
    "The numbers have just been increasing," said Ed Meehan of the Marin/Sonoma Mosquito and Vector Control District. "Daytime activity is an indicator of a large population."
    Mild winters the past three years have spelled good times for both roof rats and Norway rats.
    "If there's mild, wet weather, then food grows and all the way up the food chain things grow, populations grow, and that includes rats," said Mary Ann Rogers, owner of R&R Pest Control of Santa Rosa.
    Residential and commercial building also has displaced rats and brought people closer to the rodents.
    "The development has contributed to it because we're taking their home space," said Kelly Cureton, manager of Earl's Pest Control Inc. of Novato.
    "Then these customers call us and say, we've got a rodent problem, and we say, it was their home before it was your home," Cureton said.
    Rats are a nuisance because they eat food products and damage homes by gnawing on pipes, wire, wood and even stucco.
    Rats are a health worry because they can cause food poisoning and carry fleas and mites that can infest a home. Rats also can carry plague, some forms of hepatitis and typhus fever.
    The pest control district added rats to its target list three years ago. But Meehan is the only technician assigned to controlling rats, answering some 50 calls a month from Windsor to Sausalito.
    Homeowners who contact the agency are urged to rat-proof their homes to keep rodent populations from getting established.
    Sealing openings around pipes and other utility connections from outside a home and repairing broken screens and vents will keep out Norway rats seeking food and roof rats seeking areas to burrow.

    Experts say that thinning ivy and other dense vegetation where roof rats burrow also can help.
    Pet food and backyard fruit also should be kept off the ground because rats, particularly roof rats, feast on fresh vegetables and fruit.
    Pet food and backyard fruit also should be kept off the ground because rats, particularly roof rats, feast on fresh vegetables and fruit.
    "Once they're established, they pretty much stay there," Rogers said. "The succeeding generations move out in a circle. You can have fairly large populations in fairly small areas if the problem is not taken care of early."
    Prevention hasn't kept roof rats from plaguing Thomas' neighborhood.
    "They're all over," he said. "It's a major nuisance." Rats chewed the electrical wiring of his spa. Rats also chewed through underground plastic pipe to get in and out of the sewer system.
    Spring traps that kill rats and cage traps that lock them away alive help, but Thomas said he has seen rats avoid them.
    "You can only do so much about the problem," he said.
    Thomas said he fears the potential health impacts of rats if their numbers aren't brought down.
    The pest control district isn't directly involved in controlling rats because that would be too costly, Meehan said.
    The agency may seek funding from Marin County or its cities to pay for surveillance and control measures because of the large rat population. A similar proposal has yet to be drafted for Sonoma County, Meehan said.
    In the meantime, he said, the rat population should reach a natural ceiling.
    "They will reach a point when they reach their carrying capacity. It depends on the area and what people do" to control them, he said.
    Meehan said rat-proofing homes helps reduce the carrying capacity. "They will die off or start competing against each other. They have smaller litter sizes and they basically have to move out."
    Spring traps, glue boards, cage traps and weatherproof bait blocks will work to eliminate rats from homes.
    Pest control professionals also have started using rat zappers, a new device that lures rats into a metal tube where they step on high-voltage plates and suffer heart attacks.
    "Everyone's trying to build a better mousetrap," Cureton said.