PESTS : Silencing the Rat-a-Tat-Tat of Those Little Rodent Feet

Barbara doesn’t want anyone to know her last name or what city her well-kept, 20-year-old house is in. The reason? She found a rat scurrying across her patio one evening this summer. “It headed for the bushes, and I headed for the phone,” she says.

She asked exterminators about their effectiveness, their rates and their trucks. “I didn’t want some guy driving up to my house with a big plastic rat on the roof. I wanted to be discreet; this is a good neighborhood.”

But rats and mice are truly democratic animals. They infest neighborhoods good and bad, rich and poor, throughout Orange County. “When they’re spotted, people are sure they’re coming from the guy next door or the flood channel nearby,” says Gil Challet, district manager of the Orange County Vector Control District. “They can’t believe there’s a nest on their property, but that’s often the case.”

Vector Control is the county agency charged with keeping track of rodents and other pests that are potential health risks and with educating the public about eradication. The district conducts free surveys for homeowners, showing them the measures needed to prevent rodent infestation.

Complaints about rodents to Vector Control have multiplied during the past two years. At the height of the drought, there was an average of 6,000 calls per year. But as rainfall and local vegetation have increased, the numbers have climbed: Last year there were approximately 11,000 calls.

“Rodents are extremely adaptable to their environment,” says Kevin O’Connor of Global Extermination Co. in Santa Ana. “In lean years, they’ll have smaller litters; in years with more vegetation, they’ll bear more young.”

Coinciding with the ideal conditions for rodent populations is heightened public concern about a deadly strain of hantavirus, which some rodents carry and can transmit to humans.

The virus, which affects the lungs and is fatal 60% of the time, has been found in the saliva, urine and feces of deer mice and harvest mice. It has not been identified in rats and what is commonly known as the house mouse. While several cases of the hantavirus have been confirmed in mice trapped in Orange County, there have been no recorded cases here of people infected.

Rodents have been known through history for their ability to spread certain diseases. Fortunately, the diseases that can be passed from rodents to humans are not common, say health officials. “Bubonic plague is a possibility, typhus and a mild form of meningitis, but the risks are low,” says Hildy Meyers, an epidemiologist with the county Health Care Agency. “What you mainly need to worry about with rats and mice are bites and if they contaminate food supplies.” Any type of bite requires immediate medical attention.

The mice that are of concern for hantavirus--deer and harvest mice--tend to be found in open, chaparral areas, Challet says. “They’re not like the typical, urbanized house mouse, which is indoors.”

However, homeowners in areas of new construction near open fields should probably be more aware of controlling rodents on their property.

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Most of the rats in Orange County are the roof, or fruit, variety. Although they primarily feed on plants, vegetables and fruit, “They’ll eat anything,” Challet says. “If you have them in your yard, you’ll often find crushed up snail shells.”

Seeing them on fences or scurrying across wires may make it appear as though the neighborhood’s being invaded, but more than likely the occupation began long ago. “Rats and mice are nocturnal; once you start seeing them during the day, that’s usually a sign that the population is at a pretty good size,” Challet says. “They generally have a main nest and a few auxiliary nests covering two or three properties on a block.”

“It doesn’t take long to walk through your house and yard and pick out areas where rats and mice can thrive,” Challet says.

Barbara’s rat problem was traced to an old storage shed in her back yard. “There were some boxes of books and magazines in one corner that were too heavy for me to move; they had been there for years, and that’s what the rats called home,” she says.

Her scenario was typical of those encountered by rodent specialists.

“They’ll tend to nest indoors, out of the elements,” O’Connor says. “I once found an old desk that was tucked away in a garage. Rats had filled up the drawers with dog food they had collected and stored away.”

Homeowners with cats often believe that they live with an effective rodent exterminator. While felines are natural hunters, they’re not always successful against rats and mice. “They may be more effective against mice, since they’re smaller, but cats don’t always do so well with rats. Every second or third home probably has a cat, yet we still have a growing rat population,” Challet says.

Generally, pets are only in danger from a rodent if they’re bitten, but that’s not common because rats and mice tend to avoid larger animals such as dogs and cats.

If you do have pets, be aware that a common dinner spot for rodents is the half-empty pet food bowl. “Bring the bowls in at night,” Challet says. “Otherwise you’re just inviting them to your property.”

The best way to keep rodents at bay is to eliminate as many places as possible where they find shelter and food.

Any rodents in or around the house should be trapped and removed. An independent exterminator or Vector Control technician can advise you on the best course of action in your situation.

Keeping rodents out of your home and yard means putting the “S & S” method into action, O’Connor says. “You need to seal the outside of your home to prevent them from gaining entry and sanitize your yard to keep them from finding easy food sources.”

If you keep garbage cans or bins outside, check the lids. “If the cover isn’t on tight, you’re basically just putting food out for them,” Challet says. Pay special attention to composting bins, making sure the material is inaccessible from the outside.

Heavy vegetation should be thinned out, and fruit that has dropped from trees and ripe vegetables should be routinely picked. “If you have a severe infestation, you may have to pick your trees and vegetable garden clean,” O’Connor says. “The key is to discourage them from finding any food in your yard.”

Rats are known for their love of avocados, and it’s been said that after eating them they’re immune to poison. “That’s just a myth,” Challet says. “Avocado has Vitamin A, which is an antidote to anti-coagulant poisons, but there’s not enough Vitamin A to help them, and even if there was, other poisons would be just as effective.”

Preventing rodents from entering the house means carefully examining any possible entrances. “A rat can squeeze into a space only half-inch big,” Challet says. “And a mouse can get into even smaller gaps. One of the best things to do is attach a sweep to the bottom of your garage door, creating a seal that keeps rats out.”

Vents leading to a crawl space should be checked, as well as areas where pipes enter and exit walls. “These are often not sealed correctly during construction. You don’t want to leave any gap for a rodent to travel through,” O’Connor says.

Roof vents are vulnerable because they’re harder to inspect. Make sure that screens are intact and that areas where the roof line comes together are sealed.

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Only about 10% of complaints to Vector Control are for rodent problems inside a house, although that figure climbs to about 15% during the winter, Challet says. “Like any mammal, when it’s cold, they’ll go here it’s warm.”

After a house has been sealed, indoor rats and mice are generally eradicated through trapping, although the techniques differ. “Mice are relatively easy to trap; they’re curious about anything new in their area,” Challet says. Rats are very suspicious by nature, making trapping a more involved technique.

“What’s called ‘pre-baiting’ is done,” Challet says. “The trap is put out with a bait like peanut butter, and it’s left in their area for a few nights unsprung. After they become accustomed to it and eat from it, the trap is set.”

Setting out poisons might kill a rodent, but they can lead to complications after the pest has died. “If it gets in behind the wall, it can be a problem getting it out,” O’Connor says. “The exterminator finds it by the odor, which isn’t pleasant.”

Another unfortunate effect after a nest of rats or mice is removed from a home can be mites. “People will often find them after the rodents have been destroyed,” O’Connor says. “Generally the attic or wherever the nest was is fumigated to kill the mites as well.”

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Ridding Orange County of rodent problems may be too idealistic, but the Vector Control District says that by educating homeowners about rats and mice, the problem can be lessened.

“The homeowner really has to be determined to keep them out,” Challet says. “But first, they probably have to accept that they’re not coming from the guy across the fence.”

Ground Covers With Bad Taste

If you want to attract rats, plant Algerian ivy--the familiar, large-leaf variety. Rats not only love it as shelter but as food. It also harbors snails, another rat delicacy.

If you don’t want to attract rats, plant these ground covers instead:

Bronze ajuga (Ajuga reptans atropurpurea) --Bronze-colored leaves, blue flowers, two to four inches tall, hardy, sun or light shade.

Giant ajuga (Ajuga crispa)-- Large, very hardy, metallic-colored leaves, blue flowers, up to nine inches tall, sun or shade.

Chamomile (Anthemis nobilis)-- Turf up to six inches tall, can be mowed, good around stepping stones or walkways, pleasant fragrance, sun only.

Creeping speedwell (Veronica repens)-- Dense, green leaves with blue flowers, hardy, up to six inches tall, sun or light shade.

Creeping thyme (Thymus serphyllum)-- Small, light-green leaves with lavender, white or pink flowers, up to four inches tall, sun.

Dichondra (Dichondra repens)-- Usually a lawn plant, can reach three inches in height and withstand moderate foot traffic.

Germander (Teucrium chamaedrys)-- Bright-green foliage, resembles mint, spreads rapidly, lavender flowers, up to 10 inches tall, sun.

Goldmoss stonecrop (Sedum acre)-- Hardy, succulent evergreen, sun or shade, three inches tall.

Hahns ivy (Hedera helix)-- Good for erosion control, sun or shade, up to a foot tall.

Source: Orange County Vector Control District.

Rat Patrol

TELLTALE SIGNS OF RATS: If you’ve seen one, you’ve got at least that many. Half-eaten fruit on the tree or ground; empty snail shells; droppings along fence tops, air conditioners, water heaters or furnaces, and signs of gnawing are all evidence of rodent problems.

WHAT TO DO: Call the Orange County Vector Control District at (800) 734-2421 or (714) 971-2421 for a free inspection, advice and literature. Call a commercial pest control service for indoor infestations.