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Puritan Tiger Beetles, ‘Vicious Predators,’ May Soon Hunt Again

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Puritan Tiger Beetles, ‘Vicious Predators,’ May Soon Hunt Again

HADDAM, Conn. — In row upon row, 436 tiny larvae are presumably fast asleep now, a few months after they were tucked inches deep into trenches dug along the sandy banks of the Connecticut River.

The nestled larvae represent the last chance for one of New England’s most endangered species, the Puritan tiger beetle — an insect tiny enough to fit on the pad of a thumb. The species only exists in small numbers in just two spots here, and another in the Chesapeake Bay area.

“This is it for New England,” said Laura Saucier, a wildlife biologist for the state of Connecticut. “If we lose our population in Connecticut, it’s gone. The stakes are pretty high.”

Granted, the Puritan tiger beetle project — one of the largest insect reintroductions in the country — lacks the emotional appeal of protecting pandas or polar bears. “It’s not fuzzy and has a face only a mother could love, but they’re just so interesting,” Dr. Saucier said. “They’re the top predators in this food web and the food web is down here,” she said, pointing to the sand, “so we don’t know a lot about them.”

CreditKayana Szymczak for The New York Times CreditKayana Szymczak for The New York Times

But for an ecosystem that runs from the Canadian border to the Long Island Sound, maintaining ecological balance is crucial, said Rodger Gwiazdowski, the entomologist who is leading the project and who has been dreaming for nearly two decades about restoring the Puritan tiger beetle.

The beetles aren’t an obvious missing link in an ecological chain; no other creature is known to have died or flourished as their numbers diminished, as far as Dr. Gwiazdowski knows.

But “they’re part of a healthy river,” he said. “When we see a stretch of healthy river, we see beetles.” So, restoring them should help support the health of New England’s longest river, whose watershed is home to more than 2 million people. “It’s powerfully naïve to think it means nothing” to allow the Puritan tiger beetles to disappear, he said.

Which is why Dr. Gwiazdowski found himself motoring down the Connecticut River in October, remembering all he’d done to ensure that these immature beetles arrived safely at their destinations. If the boat should sink, he had a plan to float three tubs of beetle larvae to shore.

Still, preparations and plans can go awry. One beach that he had staked out turned wetter than the week before, not ideal for larvae that can’t swim.

So rather than installing the larvae into several nearby plots, Dr. Gwiazdowski and crew were forced to release more than 200 of the larvae into one 12-meter stretch of relatively dry sand. There, the larvae created some sort of vertical bubble inside their burrows, protecting them from rising river levels.

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Laura Saucier, Joe Elkinton and Rodger Gwiazdowski clearing areas along the river banks in October.CreditKayana Szymczak for The New York Times

For the winter, the beetles are in a state of torpor — essentially hibernating — all season long. The more mature ones will emerge as adults some time early next summer, if all goes well. They can last the winter without food, but even the larvae are predators. They’ll hide in their burrows, waiting for prey to walk by that they can pull down into their tunnel and consume.

Their eyesight is among the most acute of any known insect and they display a very fast muscular response time, Dr. Gwiazdowski said. “Coming and going, they’re vicious predators.”

They look a lot like other tiger beetles, but have long strides, are slightly longer and sleeker, and their wing covers are a little shinier and more bronze. “Even in the sand, I can tell species apart by how they move,” he said.

It’s unclear when the Puritan tiger beetle began disappearing. It was first named in 1871, but wasn’t nearly wiped out until the late 1980s, perhaps as the result of development along the river.

Dr. Gwiazdowski doesn’t want to pinpoint the locations where the beetles still live or where he’s released the larvae. Insect collectors have been known to kill beetle populations, so he avoids specifics.

For the release, he picked locations along the Connecticut that already had other species of tiger beetles — ones that are less selective and hardier than Puritans. He hopes their success means the Puritans will survive, too. But even if the Puritans all die, he said, from a scientific perspective the experiment will have been a success.

“I can try and fail and that’s O.K.,” Dr. Gwiazdowski said. “The scientist in me doesn’t care, as long as we know why.”

The containers that housed the larvae.CreditKayana Szymczak for The New York Times CreditKayana Szymczak for The New York Times

Last summer, Dr. Gwiazdowski and his team minded 30 or so pairs of adult Puritan tiger beetles they had caught in the spring, feeding them crickets and carefully harvesting their eggs every day, including weekends.

Adults are easy to catch but hard to relocate, Dr. Gwiazdowski said. With previous releases of adults, the insects were never seen again, so scientists don’t think the populations survived. The plan this time was to release larvae at different stages of development, hoping some would make it.

Raised appropriately in captivity, each female can produce 100 or more offspring. But no one knew the optimal way to raise a Puritan tiger beetle — what kind of climate, prey or sand type.

So the beetle team has been figuring it out by trial and error. Each breeding pair was kept in its own shoe-box sized plastic tub with a sand-filled Petri dish where researchers hoped the beetles would lay their eggs.

Every weekday, a staff member sifted through the sandbox looking for eggs to remove, adding live crickets for food and replacing water in gel-form so the beetles could drink. The researchers couldn’t put freshwater in the tubs, because the crickets — which apparently aren’t very smart — would drown in it.

Sara Wisner, left, and Kate Froburg, assistant lab managers at the lab in Sunderland, Mass., feeding adult beetles.CreditKayana Szymczak for The New York Times
The larvae awaiting transport to the river banks.CreditKayana Szymczak for The New York Times

Egg-laying provided another obstacle. Because beetles exist naturally on the flat surface of a beach, they weren’t familiar with jumping or climbing into their makeshift sandboxes. Filling the tubs with too much sand would make the eggs difficult for researchers to find. Ramps of one type or another were too soft or too hard. Finally, the team obtained fresh clay from a quarry in Vermont. “The day we put the clay ramps in, the fecundity exploded,” Dr. Gwiazdowski said.

Restoring the Puritan tiger beetle’s population had been a fantasy of his since he was an undergraduate student. But it wasn’t until Dr. Gwiazdowski received a pilot grant in 2015 and another in 2017 from the Fish and Wildlife Service that he could start the reintroduction project.

The challenge then became “how to rear at scale,” he said. “No one’s done this before.”

He spent most of that money on salaries and on his Sunderland lab, housed in a former salmon hatchery, where multi-million-dollar, decades-long efforts to reintroduce East Coast salmon had failed. In giant tanks that once housed fish, he installed tubs of Puritan tiger beetles and enough insects to keep them well fed.

At the insect’s rearing lab in Sunderland, beetle-related artwork adorned a refrigerator.CreditKayana Szymczak for The New York Times

All 463 larvae were raised in this room, whose climate was meant to constantly resemble a humid summer’s day at the water’s edge. A fan blew constantly across a humidifier, creating a fog-machine-like effect that kept the room at 60 to 80 percent humidity — enough to stop the sand from drying out, but not so much that the walls would mold.

It takes two to three years for an egg to mature into an adult Puritan tiger beetle capable of reproduction. In the lab, scientists can speed up that process and keep adults alive longer.

In nature, each female insect will reproduce herself — leaving on average one mature offspring behind, said Joe Elkinton, a professor of environmental conservation at the University of Massachusetts Amherst, who has collaborated with Dr. Gwiazdowski and helped with the release. But in captivity, insects can multiply themselves 100-fold in one generation, suggesting how many are lost to predators, starvation and other challenges. It also means that reared properly in a lab, it’s feasible to mature enough larvae to make a difference at the population level, Dr. Elkinton said.

Males are usually a little bit smaller than females. Researchers put a red dot on the males so they could be easily spotted and grabbed. From midsummer until the larvae collection was complete, the males were moved every day into a tub with a different female to promote breeding. Some females laid no eggs at all; one laid 126.

“When you put life in a box, it gets very complicated very fast,” Dr. Gwiazdowski noted.

Releasing the 463 larvae on the river banks was “like kicking the kids out at 18,” Dr. Saucier joked.

Dr. Gwiazdowski remained optimistic: “It’s easy to say goodbye. I’m really happy for them.”

Along Higganum Meadows in October, the team positioned larvae that will hibernate all winter and researchers hope will mature by late spring.CreditKayana Szymczak for The New York Times
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