It’s that time of year again, and the mites of spring are on the march. The majority of Lyme disease infections will take place over the next two months, because nymphal deer ticks, the primary vector for Lyme disease, are in search of their first blood meal. They’re ravenous, minuscule, and newly infected with Borrelia burgdorferi — the bacterium that causes Lyme disease — from the white-footed mice they cozied up with over the winter.
Lyme disease is only one of the tick-borne illnesses Islanders and visitors can contract from a tick bite. Babesiosis, ehrlichiosis, and tularemia also lurk. The recent colonization of Lone Star ticks on the Island adds Southern tick-associated rash illness (STARI) and spotted fever to the list of potential maladies. Reports of Borrelia miyamotoi and Powassan virus showing up on the Cape last year have ratcheted up the collective anxiety.
As the public becomes more aware of tick-borne illnesses, so does concern about the overuse of pesticides, an already percolating issue on Martha’s Vineyard with the Eversource herbicide debate. Also at issue is the efficacy of “organic” pesticides versus the potential liabilities of synthetic pesticides.
According to the Centers for Disease Control (CDC) “Chemical intervention should focus on early control of nymphal [deer] ticks, the stage most likely to transmit Lyme disease, by spraying once in May or early June.”
Landscaper Zada Clarke, owner of Bewildered Gardner, with 20 years experience in the field, said she’s seen an increase in homeowners spraying insecticide, in larger amounts, which she attributes in part to last year’s reports of the Powassan virus showing up on the Cape.
“It’s understandable that people would react this way, but you can’t drench the soil, you can’t drench your entire yard,” she said. “Anything can be toxic if you use too much of it. People have to realize the damage overspraying can do to our water and to the bee population.”
According to tick expert Sam Telford, professor of infectious diseases at the Tufts University School of Veterinary Medicine, Powassan has been around for a long time. “We found Powassan in ticks [on the Cape] as early as 1999 or so,” he wrote in an email to The Times. “So the real question to me is why don’t we see a lot of cases. It is not like these are new infections.”
Ms. Clarke said she’s seen a decline in ticks on properties that do targeted spraying with both organic and chemical sprays. She expresses concern, however, about the overuse of pyrethrum. “We have to fight against overreaction. Pyrethrum is for air, for foliage, not soil. You have to clean up the leaf litter. You just spray a five-foot border around your property. You have to accept this is a control; you can’t eradicate ticks, no matter how vigilant you are. It’s important that companies educate their customers on this too.”
Matt Poole, Edgartown board of health agent and co-chairman of the Tick-Borne Disease Initiative (TBDI), agreed with Ms. Clarke. “Balance is important. You can’t poison ticks into oblivion. That’s not the answer,” he said. Anecdotally, Mr. Poole said he’s heard from reputable sources that some of the organic tick sprays do work, but ultimately, it comes down to individuals taking precaution — like clearing leaf litter and wearing permethrin-treated clothing. “I call it ‘tick IQ.’ I think the Vineyard has definitely improved in this area,” he said.
Mr. Poole said that organic pesticides can also cause collateral damage to other species. “Just because a pesticide is organic doesn’t mean it’s not potentially harmful. It’s a killer. There’s nothing that’s magic about organic.”
There are advantages to synthetic pesticides, he said. “Synthetics can be refined, and there can be a more high-tech approach with a controlled release,” he said. “Organic has less potential for controlled release. Synthetics also can potentially be more targeted to the species.”
Targeting locations to spray is also important.
“You don’t need to do radical treatment in places where people are never going to go,” he said. “Don’t spray because you think you need to; spray because you’ve confirmed you need to. Have Dick Johnson do a yard study; find out what’s really there.”
Dick Johnson, field biologist for the Tick-Borne Disease Initiative, has been doing tick surveys on the Vineyard for seven years. He began this year’s surveys two weeks ago.
“I just did a yard in Aquinnah, and found pretty much everything, adult Lone Star ticks, adult deer ticks, deer tick nymphs, and lots of dog ticks,” he said. “This seems to be the worst year for dog ticks than anyone can remember.”
Dog ticks are vectors for Rocky Mountain spotted fever, tularemia, and canine tick paralysis.
“My impression is that organics work,” he said. “Keep in mind, just because it’s natural doesn’t mean it’s not harmful. Arsenic is natural. You don’t want to be putting that on your cereal.”
Anecdotally, Mr. Johnson said he found organic treatments to be about 50 percent effective and chemical treatments to be about 80 percent effective. “I like organic because you can use it around wetlands. You shouldn’t use permethrin around wetlands; that’s a big advantage with organics. Places with a lot of ticks tend to be near water.”
Reducing potential collateral damage is another advantage of organics, in his view. “In my mind there’s no doubt that overall, organic sprays cause less damage to other living creatures,” he said. “Permethrin persists in the ground. It’s also more effective because of that. If you’re really concerned about damaging other species, like bees, but still want to use permethrin, use the granules. They sit on the ground, where bees looking for pollen aren’t going to get it. Ultimately it comes down to a personal decision to the landowner. Do you want to use a less effective spray with fewer environmental detriments, or use permethrin, which might have more impact on other living things down the line?”
Mr. Johnson said his yard studies have shown that in addition to leaf litter, grass along driveways and areas around highbush blueberry bushes often have a high concentration of ticks. Lone Star ticks seem to favor honeysuckle and bittersweet.
Mario Spindola, owner of the ohDeer franchise on Martha’s Vineyard, which sprays properties with a mixture of natural oils, including rosemary, peppermint, and wintergreen, told The Times his clients have been very pleased with the results, and he can barely keep up with demand.
“This is our fourth summer; we’re up to 225 homes,” he said. “My clients tell me they see a drastic reduction in ticks.”
Mr. Spindola said the spray used by ohDeer is potentially toxic to animals besides ticks, but for a very limited time. “The oils are strong enough to kill on contact when it’s still wet. But once it dries, it becomes more of a repellant,” he said. “It’s not like a chemical pesticide, where you spray it once and it kills everything it comes in contact with. We stay away from pollinating flowers. If a bee comes in contact once the spray has dried, it will not die, and it will not bring the chemical back to the hive, which is a big issue with chemical sprays.”
Mr. Spindola said a key to success with organics is frequency and technique.
“We spray once a month, from April through October. It’s not a onetime application. If needed, we’ll do it more often, but most people remain on a monthly schedule. We also use a pressurized system, which turns over the leaf litter, and we use an average of 100 gallons per house.”
Mr. Spindola says he does follow-up tick surveys, using the same technique as Dick Johnson, dragging a flag over tick-friendly areas. “We might get one or two at the most, but you can’t kill everything.”
New study knocks organics
Dr. Thomas Mather, director of the University of Rhode Island’s Center for Vector-Borne Disease and the TickEncounter Resource Center, recently completed a field study to test the effectiveness of “natural” pesticides on ticks.
His conclusion: Organic sprays don’t work.
“Our experience was largely disappointing,” he told The Times. “We tested 11 different natural products. I don’t think the natural products are delivering the control people think they are getting, which I think is a big problem. There’s a lot of alchemy going on out there.”
The study, which is documented on the TickEncounter Resource Center website, was funded by the CDC. It tested a variety of products on groups of 60 deer ticks, with one application over a two-week period. Variations of cedar oil, rosemary oil, and clove oil were among them. Bifenthrin, the industry-standard synthetic chemical, was used as a control. It was 100 percent effective, four weeks after application. Mr. Mather said some of the natural products were about as effective as water; some gave up to 30 percent control. “But we don’t think 30 percent control is very good. If your product doesn’t produce at least 85 percent control, I believe you’re probably misleading the public that you’re controlling ticks,” he said. “I think there’s a tremendous amount of misunderstanding among consumers when it comes to a choice of using natural versus synthetic sprays. If it was an equal choice of using a natural product or a synthetic chemical, everyone would opt for the natural product. Most people don’t question that they work. Natural products are exempt from EPA regulation, and there’s been no assessment of how effective they are against ticks. Most people don’t know that.”
One exception was Alaskan yellow cedar oil, which performed well in tests, with 83 percent control. However, its efficacy is short-lived, and it is not available to consumers. Tests on red cedar, which is readily available, showed negligible results.
Mr. Mather said first and foremost he’s an ecologist, however he believes many people are too close-minded about using chemical agents.
“Most people close their minds when they hear the word ‘pesticides,’” he said. “The little bit of spraying done by well-trained applicators is negligible. You don’t spray it in water and you don’t spray on flowering plants, which you don’t need to because that’s not where the ticks are. I’ve had my yard professionally treated for over 20 years, and I have plenty of bees and butterflies and all kinds of insects.”
The difference between “hazard” and “risk” is a critical distinction, in Mr. Mather’s view. “You mostly hear about the hazards of pesticides, but people need to understand that something can be hazardous, but when used in small quantities, it can be very safe to use,” he said. “They put a tiny amount of bifenthrin into 100 gallons of water. When used appropriately, bifenthrin is tremendously effective against ticks, and the impact on other animals is extremely minimal … I don’t want to sound glib, but if a tanker truck full of bifenthrin went off the bridge into Narragansett Bay, the only fish killed would be the ones hit by the truck.”
Asked if the assertion by Mr. Spindola, that the key to effective organic tick protection is repetition, Mr. Mather said, “It’s possible. I can’t discount that. I feel like it’s wishful thinking until proven otherwise.”
“OhDeer has been in business in Wayland for 10 years,” Mr. Spindola said. “If it wasn’t effective, I think we’d know by now.”
Mr. Mather said his primary goal is to improve “tick literacy,” and encouraged Islanders to visit the TickEncounter Resource Center website at tickencounter.org.
The Martha’s Vineyard boards of health (MVBOH) website also has a trove of information about ticks, disease prevention, symptoms, and treatment.
Homeowners who would like Mr. Johnson to do a tick survey of their property can email him at firstname.lastname@example.org or call him at 508-693-1893.