To supply 500,000 ants, no simple ant farm will do

When the new Museum of Insects at the American Museum of Natural History opens May 4, half a million leaf-cutter ants will co-headline the star attraction.

Ants are biological masterpieces, living in enormous colonies that function as a single organism. They are sophisticated growers, gathering leaves that they use to tend sprawling fungal gardens, which provide food for the colony.

Creating the new leaf cut exhibit was a six-year journey that took the museum team — and the ants — from a farm in Trinidad, where a tangerine-sized colony was collected, to a lab in Oregon, where it was grown large enough to fill a bathtub, and then on a 2-hour drive. Six days cross country in a U-Haul truck.

And that wasn’t even the hard part. The ants, which moved to their museum habitat in January, have been slow to adjust to their new home, failing to harvest enough leaves to sustain their fungal gardens.

“We’ve had some ups and downs,” said Hazel Davies, the museum’s director of living exhibits. “Some problem-solving, as we expected, because it’s a very unique exhibit.”

Here’s how the museum finally helped the ants find their way.

To put the cultivation of ants on display, the museum designed a sprawling, open-air exhibit made of ant-tested and approved materials, from braided stainless steel to ancient Lego. “The ants had to pick a lot of things,” said Ryan Jarrett, a self-described “ant wrangler” and founder of Leaf House Scientific who collected an ant colony and served as a habitat consultant.

The design had the ants tend to their fungal gardens in glass globes and then travel an ambitious route to collect their leaves, crossing an upside-down suspension bridge and climbing up aluminum poles.

The team stocked the foraging area with caramel berries and filled the surrounding trench with water to help contain the ants.

Then, they loaded ant-filled orbs, temporarily attached to Play-Doh balls, into the gallery. (A hand-held vacuum was deployed to collect the ants that ventured out of the orbs to forage, sucking the insects into a “friendly tornado,” as Mr. Garrett puts it.)

They separated the orbs and waited for the ants to find their way, a process they expected to take at least several days.

It took weeks. Some ants quickly made their way up the flyover and even down the ant highway leading towards the foraging area, but it seemed that they had stopped there. “We knew it was a big ask,” said Ms. Davies. “It’s like you’re heading downtown to look for groceries, but you’re not told where to go.”

The team needed a small subset of ants to make their way; When the first ants return from their foraging area, they leave a pheromone trail that their sisters can follow. The museum began coaxing the ants forward by placing a trail of apples and leaves.

But another problem soon arose: the exhibit, which was still under construction, was too dry for the tropical ants. A humidifier was therefore installed behind the gallery, diverting moisture into the display case.

The path of the ants was simplified, as a rope was hung across the upper bridge so that the ants did not have to cross it upside down. Another shortcut allows ants to bypass some aluminum poles.

By mid-April, the ant colonies are beginning to display leaves back to their orbs. “It felt like the ants were celebrating,” Mr. Garrett said.

There is more work to do. The ants didn’t really move on to the braided metal that looked so promising in the lab, and they kept dropping into the ditch. Mr. Jarrett recently created a makeshift “ant filter” out of blackberry branches to help the insects out.

But the team has now removed the big shortcuts, pushing the ants along more difficult paths. Just days ago, the ants had finally completed the entire path and started to make their way through a high labyrinth detour.

“I know everyone wanted the ants to easily walk straight into the forest to forage, but I think this process of them slowly getting to know their way around is really beautiful,” said Mr. Garrett. “Day after day we watch them learn.”