They scamper, we stalk

By James Ricci

May 9, 2007 12 AM PT

Times Staff Writer

IF you live in the Los Angeles area and are of the genus Rattus and the species rattus or norvegicus, the last person you want nosing around in your habitat is Ray Alegre.

A little after 3 a.m. on a recent Wednesday, Alegre knelt in the yellow industrial light of a warehouse parking lot in Commerce, getting ready to come after you. He was unwrapping a boxful of 60 ultra-sticky glue boards; should you carelessly tread on one, you might as well lie down, curl your pointy tail around yourself and get ready to meet whatever your sneaky little brain imagines to be your Maker.

“Here, we find rats,” Alegre said, nodding toward the 400,000-square-foot warehouse. “They leave the doors open, and merchandise and supplies come in, and they don’t know what’s coming in with it. When we took over this account, within the first three months we caught between 80 and a hundred.”

The 44-year-old Alegre, a technician with Covina-based Isotech Pest Management, has a reputation within his company as a man who can outthink, outplan and outmaneuver the cleverest Rattus. He is a decorated soldier in mankind’s unending war against its most fertile, unloved and constant mammalian companion -- a creature that, at this time of year, is reproducing furiously, preparing to dispatch hordes of juveniles into the Southern California landscape.

Biologists call rats commensal, which means they “share the table” with man -- an elevated way of saying they live primarily by eating our food. They are also famously neophobic -- that is, wary of new things (such as traps) that they encounter in a familiar environment.

The black, or roof, rat, Rattus rattus, arrived by ship in America about 1600. The brown, or Norway, rat, Rattus norvegicus, came around the time of the American Revolution.

In most of the United States, the Norway won out. Los Angeles, however, is among those coastal regions blessed with both varieties. The lush, ground-level landscaping favored by homeowners here offers abundant nesting for Norways, and the palm and fruit trees afford perfect harborage for roof rats.

What’s more, we have avocados, which rats love to distraction. “You’ve got an avocado tree, you’ve got rats,” Alegre’s sidekick, pest technician Miguel Garcia, likes to say.

Garcia had pulled up in the darkness just as Alegre was finishing his prep work at the warehouse. When Garcia opened the back of his Isotech truck, out wafted the atrocious odor of decomposing rats.

“Yeah, I got some doozies in there from a housing development in Newport Beach yesterday,” he said. “Three fat, juicy ones. I gotta throw them out.”

Alegre and Garcia, who is 31, slipped on bright blue plastic gloves, hefted their glue boards and flashlights, and marched into battle. For the next hour and 45 minutes, they patrolled the warehouse. They checked the locked, box-like poison-bait stations around the exterior of the building, then went inside and examined and cleaned traps set at the base of walls.

The warehouse was silent save for the distant whir of a night-shift forklift. Lights high overheard blinked on as the rat-men approached an area and blinked off as they departed. For obvious reasons, clients prefer rat-men to do their work when business is slow or not open to the public

It is an axiom of rat control that traps be placed along rats’ accustomed pathways, and in most cases, that means the bases of walls. Rats don’t see very well. In addition to being commensal and neophobic, they are thigmophilic; that is, they rely to a great degree on touch to navigate their environment.

Rats are never more comfortable than when their vibrissae -- the touch-sensitive hairs around their heads and elsewhere on their bodies -- tell them they’ve got the floor beneath them and at least one surface on their flank. They will readily venture into open areas only after that route has been marked by the droppings of other rats, so they can rely on smell after leaving the security of a wall.

The rats in the warehouse, Alegre explained, were roof rats: sleek, agile climbers sometimes observed performing high-wire acts on telephone lines. The vertical and diagonal struts of the warehouse’s four-story-tall storage racks provide ready pathways for them. To combat the “roofs,” Alegre and Garcia set glue boards in places where the rodents are likely to alight, replacing them regularly to ensure maximum stickiness.

Fortunately, rats leave plenty of evidence about their preferred routes. “Their fur is oily and dirty, and they leave rub marks for us,” Alegre said. “And you can smell them.”

On an aisle lined with boxes full of restaurant-size cans of dill pickle chips, Garcia stopped in his tracks as a small figure scurried beneath the racks about 40 feet ahead.

“Whoa, did you see ‘im?” he called. “It was a juvenile. We haven’t seen any in this aisle for a long time.”

The rat-men set new glue boards along the fugitive’s likely path.

“He’ll be caught next week,” Garcia said.

PEOPLE’S aversion to rats arises primarily from the latter’s association with disease, particularly the bubonic plague, which killed a third of the population of Europe during the Middle Ages. It was later determined that the culprit was not exactly the rat, but a flea that fed on it and other animals. The rats died of plague from the fleas, and the fleas jumped from the rats to people.

Rats, however, are definitely handy vehicles for an estimated 55 diseases. And rats and plague fill a few pages of California history.

On Jan. 2, 1900, the steamer Australia sailed into San Francisco Bay, carrying with it a contingent of rats infected with bubonic plague. Outbreaks over the next decade killed 191 San Franciscans before medical authorities solved the problem by focusing on the rats.

The last plague outbreak in the United States occurred in Los Angeles in October 1924, when a husband and wife living on Clara Street died before systematic rat-trapping and rat-proofing of houses ended the outbreak.

Such history “doesn’t mean that a rat, say, in the basement of a restaurant in Los Angeles is an imminent disease threat,” said Robert M. Corrigan, an Indiana-based pest control consultant and author of “Rodent Control: A Practical Guide for Pest Management Professionals,” one of the holy books of the industry.

“Statistics indicate they’re not all that likely to transmit diseases. But they do travel in dirty environments -- sewers and bathrooms, for example. So the potential is there to be vehicles for microbes and pathogens.”

THE gated subdivision in Newport Beach has large modern houses fronted by statuary and backed by swimming pools and spas. It is also a Disneyland for Norway rats.

The problem is the steep, densely vegetated hillside that falls away from the backs of the houses. Its lush greenery shields a perfect breeding ground for Norways. The subdivision is where Miguel Garcia trapped the three rodents that later stank up his truck.

One recent afternoon, Garcia lay on a treadmill in the garage of one of the houses, sniffing a wall. There was no doubt about it. A rat, dead about a week, probably from the poison bait Garcia placed around the premises, was on the other side, having probably gained entry through a clothes dryer vent.

Garcia had already caught one rat in the house, and how that one got inside is an object lesson in rat capability.

Garcia speculated that the invader was able to squeeze through a gap a little bigger than half an inch, between the front door and the threshold. The gap has since been closed, but other rats continue to follow the trail of scent left by the first one. Garcia lifted up the welcome mat and underneath it were fresh rat droppings.

Thanks to its collapsible skeleton, a grown rat as big as a large man’s fist can squeeze through a hole the size of a quarter. This is why the first line of human defense against rat invaders is denying them entrance in the first place.

Unscreened dryer vents, open chimney clean-outs and gaps where air-conditioning hoses enter homes are like open doors to Norway rats. Norways, which can tread water for days at a time, can infiltrate old sewer lines and -- perhaps the greatest of rat horrors -- be found in people’s toilets (flushing them does no good). Meanwhile, gaps between roofs and exterior walls beckon roof rats.

Complicating matters is that rats are persistent, powerful gnawers. Their incisors grow about half a millimeter a day and are harder than iron (rats keep them trimmed by grinding the uppers against the lowers). Rats can gnaw through structural timbers, electric wiring, aluminum sheeting and asphalt.

Once a rat colony is established, it’s only a matter of time -- and not much of it -- before their numbers increase. They are prolific reproducers.

A dominant male may mate with 20 females in six hours. Females will mate with a proliferation of males. In favorable conditions, a female can produce a new litter as often as once a month, and an average litter is nine pups. The pups themselves achieve sexual maturity in as little as eight weeks.

On the positive side, the lives of wild rats are truly nasty, brutish and short. “If they’re lucky, they’ll live a year,” Corrigan said.

As Garcia checked his bait stations and traps, which were locked against tampering by pets and children, the presence of many rats was apparent. On walkways alongside the houses were heavy scatterings of the Norway’s blunt-at-both ends droppings. Many were green from the poison bait they’d ingested, which would kill them in a few days.

Garcia found that the most visited traps were those closer to the back hillside. “This is a good sign,” he said. “They’re staying back near the hill. The first weeks, all the bait stations, even those right near the houses, were empty. The bait is working. I’m not going to get rid of them. I’m just going to try to keep the population down, to keep them away from the homes.”

GIVEN rats’ survivability and reproductive powers, they seldom can be eliminated from a habitat. But they can be controlled.

“Battles get won at the local neighborhood level, and people will say, ‘Hooray, we won’ -- and fire the pest control company,” Corrigan said. “To some degree, it’s hard to appreciate a negative. If someone comes along and eliminates the rats, and months go by and no one sees any, people think, ‘I guess we don’t need you anymore.’ And the next year, the rats are back, because no one kept them down.”

If humans don’t provide them with food, fewer rats will survive. A rat, which can grow to a pound and a few ounces, needs to consume 10% of its weight in food every day, the equivalent of an average-size man eating about 17 pounds of food daily.

When humans restrict the amount of food rats can get to, Corrigan said, the animals get stressed. They start killing one another. Mother rats start abandoning their nests.

“I always say that sanitation is rat control,” he said. “I always say we need to clean up. We need everyone to not feed the rats. They’re so dependent on us for life.”

james.ricci@latimes.com

(BEGIN TEXT OF INFOBOX)

Facts and strategies

Signs of rat infestation

* Half-inch cylindrical droppings along the bases of walls, in corners, beneath sinks, behind appliances, along external walkways.

* Scatterings of shredded paper or cardboard.

* Chewed cardboard boxes or plastic boxes or bottles.

* Chewed bottoms of doors.

How to keep rats out of, and away from, homes

* Ensure that clothes dryer vents, utility line entry points and vents leading to crawl spaces are tightly screened and/or sealed around the edges.

* Keep tree limbs trimmed and well away from roofs, especially tile roofs.

* Avoid leaving pet foods outside overnight, or move them well away from the house.