Scientists Found a Tick Weeks Ahead of Schedule. For Hikers, That’s Bad News.

On the weekend of February 11, Wil Winter, an environmental scientist for the state of Delaware, was conducting a routine search for ticks on public land in Sussex County when he discovered something surprising. 

Winter was dragging a tick flag, a 1-meter-square piece of white cloth, through the vegetation; ticks searching for a meal would drop onto it, allowing Winter and his colleagues to test them for pathogens. He expected to catch a few black-legged ticks, a common Lyme-carrying species that’s active in the cold season.

When Winter checked the flag, however, he was in for a surprise: Clinging to the fabric was a large brown-and-white tick, bigger and distinct from the black-legged ticks he had picked up. It was an adult lone star tick, and this was the earliest in the year by almost three weeks that one had ever been collected in the state.

A single tick showing up a few weeks ahead of schedule may not sound like that big of a deal. But to Ashley Kennedy, Delaware’s state tick biologist, it’s a symptom of a larger, more concerning shift. Across the U.S., ticks are becoming more abundant and active earlier in the year, and also showing up in new places. For hikers and anyone else who likes to spend time in the woods, that’s bad news.

“I will interact with people who are middle-aged, for example, and it’s the first time that they’re getting a tick bite,” Kennedy says. “They’ll say ‘I grew up here in Delaware, and I never used to get ticks when I was a kid,’ but now it’s becoming a pretty regular part of life.”

The past few decades haven’t been kind to arthropods: Insect populations around the world are collapsing thanks to the compounded effects of climate change, habitat loss, and pesticide use, with a 2020 paper in Science estimating terrestrial insects are declining in abundance by roughly 9 percent every decade. Spiders—which as arachnids are ticks’ kissing cousins—have suffered a similar fate. Ticks are an exception: Across the U.S., their numbers are booming and their range is expanding. In 1945, Kennedy says, Delaware had five resident tick species. In the intervening years, that number has more than tripled, with scientists aware of 13 species of tick definitively established in the state. 

Perhaps no species has benefitted as much as the lone star, which has become Delaware’s biggest nuisance tick. Kennedy says that lone star ticks make up 97 percent of the individuals collected by the state’s surveillance program. Lone star tick bites can have serious consequences: Although the species doesn’t typically transmit Lyme disease, it is host to the pathogens that cause a laundry list of other illnesses, including ehrlichiosis, tularemia, and southern tick-associated rash illness, or STARI. Most famously, its bite can induce alpha-gal syndrome, which causes sufferers to develop a potentially lethal allergy to red meat; people who have severe cases of alpha-gal syndrome—for which there is currently no cure—sometimes have to avoid gelatin, dairy products, and even certain brands of toothpaste.

Ironically, some of the same forces that have decimated insect populations seem to be benefitting ticks. Milder winters have allowed more ticks to survive through the cold months, says Kennedy, meaning more biting adults are ready to emerge in the spring. Ticks have also benefited from habitat fragmentation, as humans carve up natural areas with new development.

“Ticks really thrive in edge habitat, so you’re more likely to encounter them on the edge of the forest than deep in the heart of the forest,” Kennedy says. “So as the landscape becomes more fragmented, that’s creating more and more ideal edge habitat for ticks.”

Kennedy believes that this month’s record-breaking lone star tick may have emerged early due to a mild winter in Delaware.

“They’re pretty opportunistic in that if the conditions are right, they’ll come out; they’re not really on a schedule,” Kennedy says. This tick “had probably been just kind of hunkering down in the leaf litter as an adult, waiting for things to warm up.”

With tick populations rising and their active season getting longer and longer, it’s imperative that hikers take precautions whenever temperatures are warm enough for the tiny arachnids to be out and about. Besides using effective repellents on their skin and clothing, hikers must do regular tick checks to catch ticks before they bite, or as soon after they bite as possible. Despite what many believe, Kennedy says, there’s no safe amount of time for a tick to be attached to a person—evidence suggests they can transmit some diseases in as little as 15 minutes.

Besides, she says, few people are very good at recognizing how long a tick has been hanging off of them anyway.

“I’ve had people email me a photo of a tick that’s very engorged and swollen with blood,” Kennedy says. “Since I’m practiced in tick identification, I can tell that it was attached for several days, maybe even up to a week. But they’ll say in the email, ‘Here’s a tick I picked up when I was walking the dog this morning.’”