The monkeys — just six of them — arrived in the 1930s as tourist attractions, confined to an island in a Central Florida river.

The problem: They could swim.

The furry, pink-faced creatures native to Asia soon spread and multiplied in what is now Silver Springs State Park, capturing the hearts of visitors who traveled the lush river in glass-bottom boats — and confounding conservationists who want to rein them in.

They’re adorable but undeniably invasive. Experts worry their growing ranks will hurt other species. And to top it off, many of the monkeys carry a form of herpes virus.

The debate about whether and how to control the 4,000-acre park’s rhesus macaques has reignited in recent weeks after a spate of far-flung monkey sightings brought alarm and blaring headlines: “They’re here!” one news station declared after the animals showed up as far as 100 miles north in Jacksonville. But park officials are no longer trying to tamp down the macaque population.

It’s a testament, researchers say, to the messy problem of managing an invasive species that has become a tourist highlight complete with its own urban legend. (The monkeys did not escape from the set of a Tarzan movie.)

“People feel really emotionally connected to these animals,” said Jane Anderson, an assistant professor of research at the Caesar Kleberg Wildlife Research Institute who has studied the monkeys’ growth over the years. “And that makes it much harder to convey that we need to implement population management than [for] an animal that’s less cute and cuddly.”

Rhesus macaques have been known to wreak havoc on new habitats. In Puerto Rico, studies note, their introduction in the 1960s destroyed seabird populations as the monkeys devoured eggs. In the early 2000s, the island territory’s Agriculture Department found that commercial farms were losing millions of dollars because of macaques and another monkey species.

Anderson estimates 550 to 600 macaques now living in northern Central Florida and frets that more growth could bring serious consequences for area birds such as quails.

The macaque population along Florida’s Silver River had ballooned to nearly 400 by 1984, according to a paper by Anderson and her colleagues. About a thousand of the area’s monkeys were trapped and sold for biomedical research over the next several decades, they write, as people grew concerned they might be plundering birds’ nests and could pass their virus on to humans. The macaques’ herpes B has only been transmitted to people in the lab — but in the rare cases that humans get the virus, it can be deadly.

The trapping and selling drew its own backlash, however, from animal rights groups and others concerned for the monkeys’ welfare.

“It is a tragedy that wild monkeys are torn from their families and forest homes and sold to research and testing laboratories,” one animal rights organization’s spokesman said in 2013, calling on officials to catch and sterilize instead, as the Ocala Star-Banner reported.

But sterilization is expensive, researchers say, and budgets are tight. Steven Johnson, an academic who advocates cutting the monkey population, acknowledges there is no easy solution now that the macaques have made themselves at home.

“What do you do with the monkeys?” the University of Florida associate professor told The Washington Post. “If you bring them out alive, something has to be done with them.”

Other less lovable invasive Florida species, such as the Burmese python, are far easier to cull without raising a public outcry, Johnson said.

And so, since 2012, efforts to thin Silver River’s monkeys have stopped. Instead of trying to manage the population, officials warn tourists to keep their distance.

“We tell people not to approach them, not to feed them, because we want people to stay safe,” said Craig Littauer, a park services specialist. He emphasized that the monkeys are just one of a host of local wild animals, from black bears to bobcats, that can act unpredictably.

The Florida Park Service posts signs and fliers reminding people to “keep a safe distance” from wildlife, and staff may temporarily close areas where they spot monkeys during morning “safety and maintenance checks,” said Weesam Khoury, a spokesperson for the Florida Department of Environmental Protection.

It wasn’t always illegal to feed the macaques. That policy came in 2018, as state authorities warned the monkey population was spilling beyond the park, which sits just a 20-minute drive from the city of Ocala.

Monkey attacks — including one captured in a viral video — had raised concerns about aggression toward visitors. A study published in a journal of the Centers for Disease Control and Prevention had also fueled worries about herpes B, describing a “public health concern” while concluding that up to 30 percent of Silver Spring State Park’s macaques shed the virus in their saliva, urine and feces.

People can get herpes B from an infected monkey via a scratch, bite or contact with the monkey’s eyes, nose and mouth, according to the CDC. The virus brings symptoms much like those of the flu, but they can escalate to brain damage or death in humans if they remain untreated.

Experts caution that such human cases are rare. There is one recorded case of the virus spreading person-to-person.

Carli Segelson, a spokeswoman for the Florida Fish and Wildlife Conservation Commission, told The Post in an email at the time of the new monkey feeding ban that the commission “supports active management” but did not give specifics.

While she said the macaques have “bitten or scratched multiple people in Florida,” authorities have yet to record an instance of the monkeys passing their herpes B to humans in the wild.

The commission is “working with our partners to explore possible options to remove the threat of free-roaming monkeys in Florida,” Segelson wrote back in 2018. But researchers say there has been no movement since, and Segelson referred questions about monkey removals to the state’s Department of Environmental Protection.

The primates appear alluring as ever to park patrons.

“First thing everyone asks about is the monkeys,” Nick Bozman, who transports tourists on the river, told the Ocala Star-Banner recently. “They are good for my business.”

He knows there are costs, too.

“They are not supposed to be here,” he told the paper. “It’s a double-edged sword.”

Karin Brulliard contributed to this report.

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