By Jason Hill, Vermont Center for Ecostudies

It’s hard to miss the plethora of lawn signs around the Upper Valley, and I’m not talking about the political ones. The signs on my mind for the past several years are typically written in eco-green font, advertising that a property has been sprayed with pesticides for ticks. Between walking my kids to school and biking around town, I’ve noted advertisements for at least 14 companies or individuals offering their services. To the best of my knowledge, there are at least 24 different pesticides used on lawns for ticks throughout our towns. As a colleague at Vermont State University put it, “It’s like the Wild West of pest management at the moment.”

I entirely get it. As an ecologist, lifelong hunter, and outdoorsman, I estimate I’ve removed more than 1,000 ticks from myself during research and jaunts in the woods. A few weeks ago, while conducting butterfly surveys on a powerline, I removed and collected dozens of ticks over approximately two hours. Ticks are a genuine public health concern, and Vermont data show they are expanding northward in our state. We also have several new species moving in, including the Lone Star Tick, responsible for alpha-gal syndrome — a potentially severe allergy to red meat triggered by their bites.

As Jenevra Wetmore wrote in this column last July, ticks are one of the most visible signs of climate change reshaping life in Vermont. The fear driving homeowners toward pesticide services is not irrational. But it’s important that we empower ourselves with scientifically backed data when making decisions that impact us, our neighbors, and the wildlife we share and purposefully attract to our yards.

Over two years, the Vermont Center for Ecostudies studied residential tick-control pesticides across the Upper Valley. Nearly 500 landowners volunteered their properties, and we surveyed almost 200 of them — roughly half sprayed with essential oil pesticides, half using no chemicals — counting ticks and insects before and after spraying.

Essential oil pesticides reduced tick density by roughly 70% in the days following treatment, consistent with similar published research. But we found no long-term benefits for properties that sprayed more frequently or for more years — including one property sprayed nearly 100 times since 2015. Our data suggest that spraying for ticks is like mowing your lawn: it looks good for a while, but you’ll be doing it again soon. This is precisely why many companies recommend they return every three to four weeks.

There’s also no evidence that spraying keeps you safer. The largest randomized controlled study on that question (Hinckley et al. from 2016, which included 2,727 homes from the Northeast) found that spraying pesticides temporarily reduced ticks, but those homeowners did not have significantly fewer tick bites or cases of Lyme disease and other tick-borne illnesses after their yards were treated. The precautions that are proven to work — daily tick checks, tucking pants into socks to give you longer to spot ticks, applying permethrin to shoes and lower pants — remain essential regardless of whether your lawn is sprayed.

And the invertebrates and pollinators that visited the sprayed yards in our study? Spiders, butterflies, moths, bees, and true bugs all declined 25 to 30 percent in the days following pesticide application. In an era when insect populations face a multitude of stressors from light and chemical pollution to habitat loss and systemic pesticides, every backyard matters. There is no pesticide that only kills ticks.

On September 17, the Vermont Center for Ecostudies and Sustainable Woodstock will host a free screening of The Cost of Control: Tick Spraying & Backyard Biodiversity at Woodstock Town Hall Theatre. This 24-minute documentary follows residential tick-control practices across the Upper Valley. I’ll be there to answer questions afterward. Tickets are available at https://costofcontrol.eventbrite.com.

Jason Hill is a quantitative ecologist with the Vermont Center for Ecostudies and an Adjunct Assistant Professor at the University of Vermont. This research was supported in part by the One Hive Foundation.