Not long ago, I went for a walk with friends across a field near my house in New York State. As we stopped to rest, something moving in my pants caught my eye. There were about a dozen reddish-brown ticks crawling on my legs. I looked closer and found ticks tangled in my socks, hung on the inside of my shoes, hung with my legs attached to the backs of my knees. The large, American dog ticks were easy to spot, but the small, black-legged poppy-sized nymph ticks were harder to find. I was still pulling them away from me days later.
Northeasters are used to living with ticks, but this season feels unusually intense. An unofficial survey of my friends revealed some horrifying anecdotes. A landscape designer said she was bitten by more ticks than ever this year. The owner of a local wine shop pulled a tick from his hair at the Atlanta airport, who had somehow managed to accompany him on the plane traveling south. A person lives with (probably permanent) trauma from finding a tick attached to his nipple.
Anecdotal evidence of a busy year for ticks is confirmed by the data, said Richard Ostfeld, a disease ecologist at the Carrie Institute for Ecosystem Research in Millbrook, New York. It is still too early in the season to say exactly how this year ranks compared to previous years, but early returns indicate that there was an explosion of ticks this spring. “All these people who are complaining about a terrible year,”
The tick boom is not exclusive to the Northeast. Tom Mater, an entomologist at the University of Rhode Island and director of a tick awareness program called TickEncounter, said he had seen a rise in reports of sightings and bites from American ticks in the country this year. TickEncounter, which crowdsources tick data from people across the United States, shows that applications for American dogs increased by 30 percent in April compared to March, about 10 or 15 percent higher than usual. “They’ve had a good year so far,” Mater told Grist.
Jean Cao, an associate professor of disease ecology at Michigan State University, said she had noticed more ticks this season as well. When she talks to colleagues in Michigan, Wisconsin, Maine, and even Quebec, Canada, she hears the same story: “It’s a big year.”
American dog ticks are large and noticeable, which is why when people report tick encounters, Mater said they often report dog ticks. In the northeast, where the risk of tick-borne diseases is extremely high, the most dangerous ticks are currently small black-legged ticks in the nymph stage, the second stage of the three-stage, two-year life cycle of the black leg. Nymphs usually come out of hibernation in May, peak around Memorial Weekend, and remain highly active until July, just as Americans head out for outdoor fun.
“The nymphs are really hungry when they show up,” Ostfeld said. “And they look like they’re on top this year.” This is a major public health problem. Black-legged nymphs carry Lyme disease, which can cause joint pain, limb weakness and flu-like symptoms in humans. And they are even harder to see than adult black-legged ticks. It doesn’t take long – about 36 to 48 hours – for a tick to infect a human host with Lyme. As a result, people who negotiate with Lyme usually experience symptoms around this time of year.
There are a number of reasons for this year’s tick boom, including climate change. Climate change makes the “shoulder seasons” warmer in spring and autumn, which means longer tick feeding seasons. And rising temperatures are allowing ticks to trade in the United States. The lone star tick, an aggressive tick whose bite can cause people to develop a severe allergic reaction to red meat, has been making its way north of the southern United States for several years. Warming winter temperatures could also push ticks, Cao said. “It definitely looks like a mild winter is helping them survive,” she said. Urbanization and fragmentation of forests also play a role, as do rodents and deer, which do a great job of gathering ticks in one place and leaving them in another.
The main reason why black-legged ticks thrive in the northeast this year is related to acorns, Ostfeld said. In 2019, oak trees landed a large harvest of acorns on forest floors across vast stretches of the East Coast. The abundance of hardwoods was a boon for rodents of all kinds – especially mice, which are major carriers of Lyme disease. The rodents survived well this winter and began spring breeding in 2020. When baby ticks with black legs hatched this summer, they did not have a shortage of mice to feed on. A year later, these baby larval ticks turn into nymphs – ticks pose a risk to so many of us this summer.
Climate change has an indirect impact on these major years of acorns or “side events,” Ostfeld said. Studies show that oak trees are able to produce a lot of acorns when they can photosynthesize and store a lot of carbon. The longer growing seasons, in addition to the warmer and wetter conditions we get in the northeast, help oaks do this. And carbon storage is even easier to do when atmospheric carbon is at record highs. “If it’s really warm and wet, oak trees can get to the point where they can release acorns with a lot of armor sooner and probably with more armor,” Ostfeld said. “So there is some evidence of a climatic signal about the ability of oak trees to produce armored acorns.”
A certain amount of global warming can be baked, but tick-borne diseases are not inevitable. When you go out, experts recommend wearing long light pants, teaming up with a friend for daily tick checks, and avoiding tall grass when possible. I also recommend protecting your nipples at all times.