Ticks are taking over city parks. Here's how to avoid them.

National Geographic

20 hours ago

Lone star ticks (Amblyomma americanum) like the one pictured here were historically concentrated in the southeastern and south-central United States. But experts say they're creeping into unexpected new territories—including northern cities. Photograph by Joel Sartore, National Geographic Image Collection
It's not just the hiking trail where you need to worry about ticks. These arthropods are now a problem in major cities—and they've brought disease with them.
In the compact backyards of Staten Island, Maria Diuk-Wasser was surprised by what she saw. Ticks—and lots of them—nestled in wood piles, between leaves, and underneath bird feeders. It was more than she found in the previous year, and the year before that.
Diuk-Wasser, a disease ecologist at Columbia University, had been tracking tick activity in the New York City borough for four years ending in 2021, and found that, year after year, ticks were expanding both in numbers and geographically. 'There were many more ticks in more of the parks, and more and more backyards,' Diuk-Wasser says. And early data suggest a similar phenomenon may be unfolding nearby in Queens and Brooklyn.
What's happening across New York City is reflective of a larger trend: Tick populations are booming across the United States—as are tickborne diseases, like Lyme disease, which have more than doubled over the past two decades. And when there's an explosion of ticks, we inevitably see more of them crawling across cities, says Diuk-Wasser.
Indeed ticks, as growing evidence shows, are an emerging urban threat. Here's what you need to know about where to find them—and how to protect yourself from tickborne diseases. How do ticks get into cities anyway?
There are multiple species of tick, but in the United States, researchers are most concerned with four—the black-legged (deer) tick, the lone star tick, the dog tick, and the longhorned tick. Many have been venturing into regions they haven't historically called home, and they're multiplying.
Back in Staten Island, for example, Diuk-Wasser and her team recently recorded a startling spike in deer ticks (long-term residents of the eastern U.S.), lone star ticks (which have historically been concentrated in southeastern and south-central states) and longhorned ticks (which were found for the very first time in the U.S. in 2017). 'They really spread in a matter of years. It was very fast,' she says.
(Lyme disease is spreading fast—but a vaccine may be on the way.) Where guests are guardians
But what's really alarming is the rise of the one species that causes Lyme disease—the black-legged deer tick. According to Diuk-Wasser, these arthropods can live in any area that's forested or contains leaf litter—the layer of dead leaves, twigs, and plant debris that provide ticks with the thick humidity they need to stay hydrated. That means a leafy park in the city can be just as attractive as the undisturbed woods they've commonly used as habitat.
And ticks have moved into these parks by hitchhiking on the backs other animals. Ticks can exist wherever there are hosts—whether that be raccoons, mice, birds, squirrels, or possums. That's why you'll even find ticks in Central Park, a greenspace famously landlocked by concrete.
But in order to truly thrive, ticks require deer. As such, the biggest factor that influences whether an urban tick community will swell is if there's a pathway for deer to enter. 'As long as deer visit, you will find ticks,' Diuk-Wasser says. For example, ticks were able to take up residence in Staten Island on the backs of the deer that swim to the borough from New Jersey. What's causing so many ticks to invade cities?
Let's start with land use changes. Ticks long occupied the land where cities now stand, but were displaced in the 1800s as forests were knocked down for agricultural purposes—forced to go wherever trees were lush and leaves were moist. But as farming declined in the U.S. in the 1900s and people abandoned their pastures, areas near cities were reforested—and many towns and cities on the East Coast and up in the Great Lakes were built smack in the middle of those forests, says Nick Takacs, a Northeastern University biology professor who studies ticks. In the years that followed, wildlife—including deer and white-legged mice—returned, ticks in tow.
'We densely colonized a lot of their environments, so they had no choice but to adapt and live in the environments we shared,' Takacs says.
Many of the animals that make for ideal tick hosts actually prefer to hunt and live near what's called "the edge"—the space where two habitats like the woods (that offer protection) and grasslands (rich with edible vegetation) collide. So as we've built sprawling cities near and in forests, wildlife has migrated to the edge and into nearby parks and backyards, transporting ticks with them, says Diuk-Wasser. It doesn't help that deer populations are multiplying due to increased hunting restrictions and fewer predators. The same is happening with mice.
(This tick bite could make you allergic to red meat—and it's spreading.)
At the same time, climate change is majorly impacting tick activity. Decades ago, ticks would die out come winter, but warmer weather has extended tick season. 'Adult ticks can be active in the winter if it's above 40 degrees, which happens all the time now,' says Diuk-Wasser.
Additionally, regions that were once too frigid for ticks are now suitable for them. Until recently, deer ticks were mainly concentrated in the southeastern U.S., but they—and the pathogens they carry—moved north, planting roots all along the Eastern seaboard and into Canada. Ticks can now feed and breed year-round. They're proliferating—in rural spaces and urban ones.
Even the deadly brown dog tick, which becomes more active and aggressive in extreme heat, is infiltrating California cities, says Janet Foley, a veterinarian and disease ecologist at the UC Davis School of Veterinary Medicine. Once found in rural desert areas, these ticks are finding places to thrive in cities that are getting both warmer and dryer. 'The hotter it gets, the more likely they are to feed on anything,' she says. How should you protect yourself from ticks in cities?
The odds you'll be exposed to an infected tick in a city park is on par with the chance you'll run into one on a wooded hike. In some cities, roughly 20 to 30 percent of baby ticks (nymphs) are infected with the bacteria that causes Lyme disease, research shows. 'You do see cases where people acquired Lyme disease from urban parks,' says Foley.
(How to protect yourself from ticks—and what to do if you're bitten.)
Therefore, you should protect yourself in certain urban greenspaces the same way you would if you were hiking or camping. You don't need to worry as much about being bitten in Central Park (though, yes, it has ticks too), but if you're visiting a city park or backyard that wildlife can access from nearby woods? It's a good idea to use DEET, wear permethrin-treated clothing, and check yourself for ticks, says Diuk-Wasser. If you wander off the main trails, try not to brush alongside high grasses as that's where ticks cling to stems, waiting for you.
This isn't to deter you from being in nature—it's just to inform you that ticks are all around us, even where there are taxis and stadiums. 'Our cities are not as domesticated as we thought they were,' says Takacs. 'We have to adapt to that.'