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The use of mothballs to ward off rodents from cars parked at Corn Creek Boat Launch may be effective, but it’s still illegal

Some people have been using moth balls to deter small rodents from climbing into the under carriage of their cars and chewing on wires while they're away from their vehicle enjoying nature. (Pete Caster / Pete Caster/Lewiston Tribune)
Some people have been using moth balls to deter small rodents from climbing into the under carriage of their cars and chewing on wires while they're away from their vehicle enjoying nature. (Pete Caster / Pete Caster/Lewiston Tribune)
By Eric Barker The Lewiston Tribune

LEWISTON – A clever hack being used by river runners to protect their cars at the Corn Creek Boat Launch on the upper Salmon River has drawn the ire of officials on the Salmon-Challis National Forest.

According to a news release from the agency, some rafters and kayakers who leave their vehicles parked at the boat ramp while floating the river place mothballs under their rigs. The idea is to deter mice and other rodents from climbing into the engine compartment and causing havoc.

The mothballs deployed by river runners at Corn Creek are meant to deter the messy and destructive mice, marmots, rats and other rodents. But the balls Grandma used to keep moths from chowing on wool garments are also considered a pesticide. It’s illegal for people to apply such chemicals, even in the form of mothballs, on federal land.

Salmon-Challis National Forest spokeswoman Amy Baumer said some agency workers have even become sick from constantly breathing mothball fumes at Corn Creek.

Rodents sometimes enter the dark nooks and crannies of parked car and truck engine compartments to build nests. The rodents generally make a mess when they do this, but they can also do costly damage with their teeth. Rodents sometimes like to chew on rubber, damaging fan and engine belts or the sheathing that covers electrical wires.

Even worse, some late-model cars have wires with sheathes that are soy-based and apparently irresistible to vermin. When they chew on the apparently delicious and environmentally friendly wires, they can destroy the wire harnesses, short electrical systems and causes tens of thousands of dollars of damage.

Cody Mael, a Lewiston mechanic, said he worked on a late-model Mercedes-Benz that had its soy-based wires ravished by rodents. The damage, which didn’t happen at Corn Creek, came to nearly $20,000.

“The mice got to it and completely destroyed it,” Mael said. “Luckily it was under warranty.”

The internet is rife with such stories, and class-action lawsuits have been filed against automobile manufactures who use the soy-based wiring sheaths.

The mothball deployment tactic seems to be limited to just Corn Creek.

Baumer said it has not been reported at other places on the forest where people sometimes leave their cars parked for extended periods of time.

Officials on the Nez Perce-Clearwater National Forest and the Bureau of Land Management’s Cottonwood Office said they haven’t noticed the practice at their recreation sites.

Nor has Pat Sullivan, owner and operator of Grangeville-based Central Idaho River Shuttles. Sullivan’s company shuttles the vehicles belonging to river runners from their put-in locations to their take-out destinations. During his seven years in the business, Sullivan has never had a client report rodent damage to a vehicle. But he did say some people leave their hoods propped open.

“I don’t know why,” he said.

The internet may have an answer. The site says propping the hoods open lets in moisture and light and lets heat escape, which generally makes the area less attractive to rodents. His and other sites include other tips people can use to ward off chewing vermin. They include strategies like placing traps in front of and behind the wheels, which some rodents use as ladders to reach the engines; spraying wires with Rodent Defense, a product designed to repel the pests; and wrapping the wires with pepper-infused tape.

The U.S. Forest Service news release said the use of mothballs is a violation of 36CFR, which bans the use of any pesticide aside from insect repellent. It quotes the National Pesticide Information Center as saying, “Mothballs are nearly 100 percent active ingredient, and the active ingredient may be either naphthalene or paradichlorobenzene. Each active ingredient can cause different health effects if the exposure is high enough. Mothballs slowly turn from solids to toxic vapor. When you smell mothballs, you are inhaling the insecticide. Mothballs can also be dangerous if they are chewed or swallowed. Children, pets and wildlife may mistake them for food or candy and eat them. One mothball can cause serious harm if eaten by a small child.”

Baumer said, for now, Forest Service law enforcement agents aren’t writing tickets to mothball rodent warriors and instead are choosing to inform them of the dangers.

“We are just trying to get the word out and get people educated,” she said.

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