Not long ago, I went on a trip with some friends through a field near my house in upstate New York. When we stopped for a break, something caught moving me on my pants. There were about a dozen reddish-brown ticks crawling up my legs. I looked closer and found ticks wrapped in my socks, fastened to the inside of my shoes, hanging by hooked legs to the back of my knees. The large, American dog ticks were easy to spot, but the small, black-legged nymph ticks the size of poppy seeds were harder to find. I still pulled them off me days later.
The Northeast is used to coexisting with ticks, but this season has felt unusually intense. An unofficial survey of my friends revealed some horrible anecdotes. A landscape designer said she had been bitten by more ticks this year than ever before. The owner of a local wine shop pulled a cross out of his hair at Atlanta airport who had somehow managed to accompany him on the plane south. A guy is living with the (possibly permanent) trauma of finding a cross attached to his nipple.
The anecdotal evidence of a busy cross year is confirmed by data, says Richard Ostfeld, a disease ecologist at the Cary Institute of Ecosystem Studies in Millbrook, New York. It is still too early in the season to say exactly how this year will pile up compared to previous years, but early returns indicate that there has been an explosion of ticks in the spring. “All these people are complaining about a terrible year,”
Tick boom is not exclusive to the Northeast. Tom Mather, an entomologist at the University of Rhode Island and director of a tick-awareness program called TickEncounter, said he has seen an uptick in reports of U.S. dog sightings and bites around the country this year. TickEncounter, which collects sources of cross-data from people across the United States, shows that U.S. dog brands were 30 percent higher in April compared to March, about 10 or 15 percent higher than normal. “They have a good year so far,” Mather told Grist.
Jean Tsao, an associate professor of disease ecology at Michigan State University, said she has also noticed several ticks this season. 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 tags are large and noticeable, which is why when people report encounters with ticks, Mather said they often report dog tags. In the Northeast, where the risk of tick-borne disease is extremely high, the most dangerous ticks out and around right now are small black-legged ticks in the nymph stage, the second phase of the black-legged tick’s three-step, two-year life cycle. Nymphs typically emerge from hibernation in May, culminating around the Memorial Day weekend and remaining very active until July, just when Americans are heading out for some outdoor fun.
“Nymphs are really hungry when they show up,” Ostfeld said. “And they seem to be at a peak this year.” It is a major public health problem. Blacklegged nymphs carry Lyme disease, which can cause joint pain, weakness in limbs and swollen symptoms in humans. And they are even harder to see than adult black legs. It does not take long – approx. 36 to 48 hours – for an attached cross to infect a human host with Lyme. As a result, people who contract Lyme usually experience symptom onset around this time of year.
There are a number of reasons for this year’s tick boom, including climate change. Climate change is making “shoulder seasons”, spring and autumn, warmer, meaning longer feeding seasons for ticks. And rising temperatures are allowing ticks to shift their reach across the United States. The lone star, an aggressive cross whose bite can cause people to develop a severe allergic reaction to red meat, has steadily made its way north from the southern United States for several years. Warming winter temperatures could also give ticks a boost, Tsao said. “It certainly looks like a mild winter is helping their survivors,” 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 throwing them away in another.
The main reason black-eyed ticks are blooming in the northeast this year has to do with acorns, Ostfeld said. In 2019, oak trees loaded a large crop of acorns on the forest floor over large shards of the east coast. The abundance of hardy tree nuts was a boon for all kinds of rodents – especially mice, which are the major carriers of Lyme disease. Rodents survived well that winter and got a start on spring breeding in 2020. When baby black ticks hatched that summer, they had no shortage of mice to feed with. A year later, these baby larval marks are melting into nymph ticks – the ticks pose a risk to so many of us this summer.
Climate change also has an indirect effect on these major crop years or “mastery events,” Ostfeld said. Research shows that oak trees are capable of producing lots of acorns when they can photosynthesize and store a lot of carbon. Longer growing seasons, in addition to the warmer and wetter conditions we get in the Northeast, help oak trees do just that. And it is even easier to store carbon when atmospheric carbon is at record high levels. “If it’s really hot and wet, the oaks can get to a point where they can loosen up with a large bumper crop of acorns faster and probably a larger bumper crop,” Ostfeld said. “So there is some evidence of a climate signal about the ability of oak trees to produce bumper crops from acorns.”
A certain amount of global warming can be baked in, but cross-borne diseases are not inevitable. When walking outside, experts recommend wearing long, light-colored pants, walking with a friend for daily tick control, and avoiding tall grass whenever possible. I also always recommend protecting your nipples.