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Ask Joanne

Rats! There's a rodent retreat under my hood Add to ...

I took my car in for routine service the other day and was surprised when the mechanic said that rats have been living under my hood. It sounds unlikely and I’m wondering does this actually happen, and if so what to do about it? – Dan in Nanaimo, B.C.

Whether you own a Bentley or a Pinto, the warmth of the motor, and a dark, dry hiding space under the hood can make your vehicle attractive to rodents. Depending on how often you drive, they may be using your car as a motel – or trying to set up a permanent home.

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Rats have been known to do more than build nests in automobiles. Rodents typically need to gnaw, and engine wires help satisfy their continuously growing incisors.

“There are chemicals in the wiring under the hood that they’re attracted to, and they will actually eat the insulation,” says Russ Perry, a 40-year veteran mechanic on Vancouver Island.

“They like to chew spark plug high-tension wires, and eat the rubber covers on the positive terminal wire on the alternator. It’s a protective cover so you don’t touch that terminal with a wrench and cause a spark. Without the insulation, if those wires touch each other they can cause a short, blow the fuse – or if that particular circuit is not fused, you could have a spark under the hood and maybe cause a fire if there are combustibles in that area.”

If rats are prevalent where you park, you may need to call a pest control specialist to set up a trap-and-bait program. They can also do an inspection and point out conditions that may be attracting rats to your vehicle.

Parking next to a wood pile, tall grass, shrubs, an ornamental pond or in a garage with a food source will give your vehicle more rodent-appeal. Bird feeders, compost piles and tree branches overhanging your house are also big attractants.

If you’re thinking about poison, proceed with caution.

“Anticoagulants are more environmentally friendly than acute toxins. Most anticoagulants are multiple feeding, so if a dog does get into it, a single feeding won’t kill your dog. They’d have to eat more than they would in a normal meal, so dogs are fairly safe,”says Phil Merrill, provincial rat and pest specialist, who has worked for 39 years to help Alberta keep its rat-free status.

“We don’t recommend the single-feeding anticoagulants or the more acute toxins to homeowners or those in non-agricultural areas because it’s too easy to poison pets.”

As with most animals, Merrill adds, rodents particularly dislike naphthalene crystals (a.k.a. moth balls). “If you’re going to store your vehicle, it wouldn’t be a bad idea to put moth balls up under the dash or in the firewall to repel them from using that as bedding, for insulation, or a home.”

Perry has used mesh to help rat-proof vehicles for his customers. “What rats also do is get in through the car’s air intake and build their nest in the air filter canister. I’ve put very fine mesh over the air intake for the cold air to prevent the rats from coming in. So you must mesh the air intake to the engine, and the intake to the passenger compartment.

“Many people don’t realize rodents have been visiting because they don’t open their hoods,” says Perry. “If you do have a problem, you want to take care of it right away, and before it interferes with your safety.”

Send your automotive questions to Ask Joanne at globedrive@globeandmail.com

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