When I asked James Dill, pest management specialist at the University of Maine, the best way to prevent exposure to ticks and contracting Lyme disease, he had a simple answer.
“Never leave your house,” he said, and then laughed. Staying inside would work, but it isn’t very practical. He and several other tick experts I contacted have more practical solutions, which I will get to later.
But first: Why, regular readers of this column might ask, am I writing about ticks just two weeks after I reported on a tick talk at New England Grows by Thomas Mather, director of the TickEncounter Resource Center and a professor at the University of Rhode Island?
Because Mather recommended spraying shady edges of home landscapes with bifenthrin and wearing clothing impregnated with permethrin. My editor at the newspaper and I both received emails and at least one phone call saying that those two treatments are poisons that can sicken people and kill bees and fish, and that bifenthrin has been found in Casco Bay.
Bifenthrin, used to spray yards, and permethrin, used mostly to treat clothing to repel ticks, are similar. Both are members of the pyrethroid family, which are man-made versions of a material found in chrysanthemums. They work by attacking the nervous system of insects.
The problem, according to Jay Feldman, executive director of Beyond Pesticides, an anti-pesticide group based in Washington, D.C., is that they also attack the nervous system of species you are not trying to kill – including people, pets and fish.
“Exposure to these chemicals can result in neurological problems,” Feldman said. “And the other thing is that (pyrethroids) are all identified as carcinogens. So you have a double problem of neurotoxic damage and cancer.”
A chart on the Beyond Pesticides website (beyondpesticides.org) says bifenthrin and permethrin both cause acute and chronic health problems, kill bees and harm wildlife. Bifentrhin damages surface water and permethrin damages groundwater, the difference being that bifenthrin binds strongly to soil and pollutes waters when the soil erodes.
So there is no doubt that the two pesticides can sicken people, but, as Alan Eaton, an entomologist at the University of New Hampshire, noted: Even table salt can kill you if you eat enough of it.
The question is, can permethrin and bifenthrin be used responsibly?
Permethrin is the most widely used. Charles Lubelczyk, a field biologist with the Vector-borne Disease Laboratory at the Maine Medical Center Research Institute in Scarborough, said that even organic gardeners wear insect-repellent clothing when walking through the woods.
The U.S. Environmental Protection Agency says that wearing permethrin-treated clothing is “unlikely to pose any significant immediate or long-term hazard to people” including “toddlers wearing or mouthing the clothing.” That sounds safe for people.
Feldman of Beyond Pesticides believes that significant amounts of permethrin leach out of clothing when it is washed, which is why label instructions advise washing permethrin-treated clothing separately from other laundry. Dill and Lubelczyk say that because the permethrin remains effective for 20 or more washings, very little leaches out and it is unlikely to harm the environment.
Since I can’t get the two sides to agree about permethrin, I’ll move on to bifenthrin.
First, some readers questioned whether ticks are a problem in suburban yards because deer and mice both have to be present.
Lubelczyk assured me that Lyme-carrying ticks are present everywhere in Maine – even the city of Portland. You can’t get rid of mice anywhere, he said. And I’ve seen enough deer-chewed shrubbery to know that deer are everywhere, too. So the ticks are out there and can strike anytime there is no snow on the ground and the temperature is above 40 degrees.
The EPA, along with Beyond Pesticides, says that bifentrhrin is a potential carcinogen. But can it be used safely?
Lubelczyk, Dill, Eaton and other government officials never say any pesticide, even if labeled organic, is safe. I think that response is drilled into them the first day they are hired.
But Dill did say that if the label directions are followed carefully, the risk of danger to humans and bees in using bifenthrin is low, and that it is the best option for killing ticks.
Bifenthrin is an insecticide, so like all insecticides, it will kill bees. The instructions always direct users to spray late in the day when bees are less active and to avoid spraying when plants are in bloom, when bees are likely to be present, thus limiting bee mortality.
Tick killers that are labeled “organic” are sold but, Lubelczyk said, it is “sort of like the Wild West out there with a lack of good, really solid science about what works or doesn’t work.”
Dill said a mix of rosemary and wintergreen oils has shown some good results, but that product was taken off the market for some reason, and its replacement has been less effective.
But even if pesticides kill ticks, do they help?
Feldman told me about a study by the Centers for Disease Control. That study, at 2,500 homes in Connecticut, New York and Maryland, found that while treating yards with bifenthrin reduced the number of ticks on the property, it did not reduce the incidence of Lyme disease – which means the treatment was a waste of money.
Now, as promised, here is how you can protect yourself against Lyme disease.
Experts disagree on the subject of pesticides, but everyone I spoke with agrees that the most effective tactic is to conduct a thorough tick check of your body after every day you have been outside. It takes time for the ticks to infect you – although one reader who contacted me said it is less than the 24 hours that is commonly reported. Remove ticks with pointed tweezers.
Next, wear protective clothing, even if you don’t use clothing treated with permethrin. Eaton recommended tall boots made of smooth rubber because ticks have more trouble climbing rubber than other material. Tuck your slacks into your boots. Wear long-sleeve shirts.
Use insect repellent. Beyond Pesticides believes DEET, the most common repellent, is dangerous but offers lemongrass and cedarwood essential oils as alternatives, as well as picaridin.
In your yard, rake leaf litter far into the woods, away from the areas where you spend time. The leaf litter harbors ticks and the rodents that are vectors for Lyme disease. (A note here: People promoting the health of native bees and other pollinators advise leaving leaf litter in place. It’s up to you to decide whether hindering ticks or helping bees is more important to you.)
Here is what my wife, Nancy, (also an avid gardener) and I do – and we have not been bitten by a tick since 1972 when we lived in Poland Spring and had a massive infestation of dog ticks.
We have never sprayed our yard for ticks. We haven’t used any insecticide on our yard or garden for at least 20 years, although I am researching an organic option for next year to protect our high-bush blueberries from winter moth caterpillars.
We both wear clothing treated with permethrin. When I go fishing, I wear L.L. Bean shirts and jeans factory-treated with permethrin, which works better on ticks than it does on black flies and mosquitoes. For gardening, Nancy and I both spray our slacks and socks with permethrin and will begin spraying our shoes this spring.
After an unseasonably warm Christmas, we finally have a good layer of snow. I can stop worrying (and writing) about ticks … for now.
Tom Atwell has been writing the Maine Gardener column since 2004. He is a freelance writer gardening in Cape Elizabeth and can be contacted at 767-2297 or at tomatwell@me.com.
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