It’s a cold, gray afternoon in December, and at the American Museum of Natural History, half a million leafcutter ants have searched their homes.
Ants typically spend their days harvesting leaf fragments, which they use to grow vast fungal gardens that serve as food and shelter. On many days, visitors to museum insectarium one can watch the endless river of ants carrying bits of leaf from the foraging area to the fungus-filled glass orbs in which they live.
But on Tuesday, the flow of leafcutter ants slowed, with some hardy insects seen living up to their name.
It’s hard to blame them. It was a painful, grim day – and the end of a long, eventful year for the colony. The tropical ants, harvested in Trinidad and raised in Oregon, had never set foot in New York City before last December, arriving as 500,000 insect ingénues. It took time for the ants to find their footing and for the museum employees to figure out how to create a happy home for them.
The work isn’t done yet. With the return of winter, the museum is making more adjustments to the exhibit, a fitting capstone to a year that featured a lot of learning through trial and error.
“We knew we were going to do a lot of problem-solving in the first year,” said Hazel Davies, the museum’s director of living exhibits. “We keep doing these mini science experiments.”
When the ants first moved into the exhibit in January, curators knew it would take time for them to adjust. But the transition was slower than expected. Ms. Davies and his colleagues spent weeks trying to coax the ants along the labyrinthine path leading from the fungal garden to the leafy foraging area. During those first weeks, the ants were getting so little food that their fungal flora began to shrink.
A big problem, the team soon realized, was that the air was too cold and dry for the ants, which prefer hot, humid weather. Not only is it winter in New York, but the museum’s new insectarium is still under construction, making climate control difficult.
So the museum installed a humidifier behind the display case and created temporary shortcuts to make searching easier. By the time the insectarium opened in May, the colony was humming.
The ants thrive during the sticky summer months, harvesting leaves so quickly that the digging site requires daily restocking. The crew experimented with different leaves, including maple, azalea and mulberry, which became favorites. Sometimes they even treat the ants to what they call “fast food,” providing old-fashioned oats, which the ants don’t have to cut before harvesting. (“They grab a piece of oats and leave,” Ms. Davies said.)
Over time, the ants rebuilt the fungus they lost and then some. “So we have wild animals living in the building and really thriving,” said Jessica Ware, a curator and the division chair of invertebrate zoology at the museum.
Ms. Davies and his colleagues are active as winter approaches, adding a water heater to the exhibit and covering the display case with blankets at night.
However, on some really cold and dry days, they found themselves faced with familiar climate challenges. So they coax some reluctant ants onto the search platform with a trail of leaves, and they recently installed an additional humidifier inside the exhibit. They hope the new humidifier will be enough to keep the ants active for months to come.
Despite these challenges, the colony is growing, and the ants have started several fungal gardens in recent weeks, Ms. Davies. And even on the coldest day, the insects did not lose their haste. Although few ants were actively foraging on Tuesday, they were busy doing chores, including taking out the trash, around the house.
In some ways, the past year was a testament to the resilience of ants. Even during the tough weeks last spring, Ryan Garrett, a self-described ant wrangler who collected the colony for the museum, never doubted that the ants would make it to New York.
After all, since collecting the colony in 2018, Mr. Garrett has watched it grow from a few hundred ants with a golf-ball-size fungal garden to a 500,000-ant powerhouse with enough fungus to fill a 50-gallon trash can. “I have never lost faith in this colony,” he said. “I know what they can do.”
