McCLELLANVILLE — The swamp transformed as dusk swallowed the last of the sun’s rays. Bats flickered overhead, barely a blur against the darkening sky. A night heron squawked in the distance. The air cooled. Katydids and crickets began their evening ballad.

Eric LoPresti sat on his truck’s tailgate finishing a sandwich. He, Brian Scholtens and James Adams swatted away mosquitoes and no-see-ums as they waited for night to fall. Soon, the Santee Coastal Reserve campground was dark. The only light that remained was a soft blue glow from the lamps the group set up before sunset.

Some lamps swung in front of white sheets hanging between cypress trees. Others were scattered throughout the reserve in traps LoPresti would collect first thing in the morning. Poets for centuries have found inspiration in moths and their unwavering attraction to light. The three biologists were counting on it.

Lowcountry moths are special, the biologists said. Not only are they biodiverse and integral to the local ecosystem, but they’re also a window. Moths can offer a glimpse into how climate change is impacting the Lowcountry that other insects can’t provide.

It’s not that moths are more plentiful than other insects or more sensitive to environmental changes. Insects generally are good ecological indicators. Changes in their population and behavior can signal rising temperatures, pollution and habitat loss. What sets moths apart from other insects is documentation.

It’s unusual to have detailed local records for the tinier lifeforms, like insects, but this rarity exists for Lowcountry moths. Richard Dominick, a wealthy landowner and moth-enthusiast who lived in McClellanville, extensively documented them from 1965 to 1976.

Now, LoPresti, Scholtens and Adams are documenting them again. They will compare their findings to Dominick’s original study that wrapped up nearly five decades ago. Two years into the new study, trends already are emerging that suggest the Lowcountry ecosystem is undergoing a metamorphosis of its own.

Some moth species that were rare decades ago appear common now. Others that were common back then have disappeared. New species have moved in.

The biologists suspect warming temperatures is the catalyst for many of these changes. Other changes, though, are a mystery.

Moving north

Unlike most moth hobbyists, Dominick was laser-focused on the ones in his backyard, LoPresti said. His entire moth and butterfly collection came from the Wedge Plantation, a historic 1,500-acre property in McClellanville.

Dominick turned a cabin on the property into a tricked-out moth magnet. He replaced windows with shutters programmed to open at dusk and close at dawn. He covered the inside walls with banks of lights, LoPresti said.

Dominick collected moths nearly every night from the time he retired in 1965 to when he died in 1976. He hired an assistant and experts from around the country to help him document and record the moths he collected. Because he leaned on the expertise of others, the result was an “unprecedented snapshot of local biodiversity,” LoPresti said.

“He really intended this to be a really detailed, useful collection for studying moth behavior, what was here,” LoPresti said. “There wasn’t much known about South Carolina moths, or really moths in the South at all.”

Now, the biologists are replicating the study the best they can.

“We’re not building a new cabin and we unfortunately can’t come out every night,” LoPresti said.

The new study is taking place at the Santee Coastal Reserve, a few miles to the southeast of the Wedge Plantation, which is privately owned without public access. The reserve has similar habitats as the plantation, making it a good substitute, Scholtens said.

LoPresti, an assistant professor at the University of South Carolina, collects moths roughly every two weeks. Scholtens, a professor at the College of Charleston, joins him about once a month. Adams, a professor at Dalton State College in Georgia, joins them a few times a year.

Scholtens and Adams both specialize in lepidopterology, the study of butterflies and moths named for the insects’ scaly wings. They joked that their focus is on “the dark side” of the lepidopterology field, meaning moths — the butterfly’s night-flying counterpart.

LoPresti, a pollination biologist, turned to the dark side recently. Most of Dominick’s collection now resides at the University of South Carolina, under LoPresti’s care.

“I ended up with this collection, and it was logical,” LoPresti said. “I’ve got this 50-year-old collection, so I might as well see how the communities have changed since then.”

Over the course of 11 years, Dominick collected more than 25,000 moths representing more than 1,100 unique species. LoPresti expects to find more — between 1,200 to 1,400 species — on the landscape today. As temperatures get warmer, especially in the winter, more tropical species likely will be able to tolerate the Lowcountry climate, a phenomenon known as Caribbean Creep. The original survey serves as a baseline that will help the biologists track a northward migration of moths, LoPresti said.

The new study kicked off in 2023. So far, they’ve documented roughly 900 unique species, and they’re far from finished. 

“Almost every time we go out there, we still get species we haven’t gotten,” he said.

‘Earth measurers’

It didn’t take long for moths to descend upon the illuminated sheets. Among the first to arrive were what the biologists (somewhat affectionately) called “little brown moths” — or LBMs for short. Flashier ones made appearances, too.

“Think of a color, and there is a moth that will have it,” Adams said.

Luna moths are sea-foam green with magenta-outlined wings and dramatic eyespots. Polyphemus moths are larger than a human palm. Their intricately designed wings have large eyespots that lend them an air of mystery and send a message to predators. I’m watching you. Don’t eat me.

The oak beauty blends in nearly perfectly with tree bark. Emerald moths, a striking verdant green, live up to their name. The agreeable tiger moth looks like someone dipped it in the whitest paint.

Adams ate one once and didn’t find it “agreeable” at all.

A geometer moth caught his attention.

“The name literally means ‘earth measurer’ because their caterpillars are the inchworms,” he said.

The biologists paced between the three light sheets from sundown to a little before midnight. LoPresti and Adams mostly observed. The traps will give them what they need to study back at the lab, said Adams, who specializes in large moths.

A Luna moth entertained the group when it landed directly on LoPresti’s face.

“A nutritional runt,” Adams said, pointing to a much smaller Luna moth that landed nearby.

“He didn’t get quite as much food as a baby,” LoPresti said. The nutrients moths get as caterpillars determine their adult size, he added.

Scholtens, who studies small moths, couldn’t rely on the traps as much. He spent a lot of the evening homing in on moths smaller than a grain of rice with their wings fully outstretched.

“I just got something cool!” Scholtens announced from behind one of the sheets.

“Is it Dyseriocrania?” Adams asked from the other side without missing a beat.

“Yes, it is,” Scholtens said.

“Ah! This is my favorite,” Adams said.

Squinting, the tiny moth glittered slightly in just the right light. Highly magnified, it’s bejeweled — the wings a shimmery gold with flecks of sapphire and amethyst.

“This is a very primitive moth family,” Scholtens said. “Dominick hadn’t recorded it here.”

It could be that this moth didn’t exist on the landscape yet. Or it could be that Dominick and his team of experts didn’t focus as much on smaller moths, which can be challenging to study. Scholtens scooped it into a clear glass vile and put it in his pocket.

‘Need more’

Back at the lab, LoPresti cares for the multiple generations-worth of moths — more than 30,000 stored in dark cabinets. Most are from Dominick’s collection. Though they’re decades old, they’ve barely faded.

When comparing the moths he finds with those in Dominick’s collection, LoPresti considers presence (i.e., were they found then, are they found now?), quantity, size and the time of year they were found. Though he’s careful not to draw conclusions prematurely, early indicators suggest some species will benefit from rising temperatures while others won’t be able to tolerate it, LoPresti said.

“I can’t say if it’s good or bad,” he said. “It depends on who you are.”

He pulled out a few drawers of the Dahana atrepennis, a moth with iridescent blue and orange wings. They eat Spanish moss as caterpillars and are one of the few day-flying moths, LoPresti said. Dominick included notes in his collection, including where he found the moths, the time of year and any other observations. Pinned next to the Dahana atrepennis, Dominick wrote a tiny note: “Need more.”

“He doesn’t have that for really common stuff,” LoPresti said. Dominick would have an easier time finding them today, he added. 

“I’ve gotten, say, four or five in a given night,” he said. “(Dominick) only got four or five in 11 years of collecting.”

This could be because of rising temperatures. The Dahana atrepennis can’t tolerate cold winters, and winters in Charleston County have been getting warmer, LoPresti said. The Charleston airport had 68 nights of frost in 1968, compared to nine in 2023, according to the National Oceanic and Atmospheric Administration. The cooler temperatures this winter bucked that trend. The snow storm in January might have knocked them back this year, he said.

LoPresti pulled out a few more drawers containing a type of tiger moth. It was common 50 years ago and it’s still common, but they’re getting smaller. Rising temperatures could be causing the insect to fly earlier or later, which could have a ripple effect on the ecosystem.

Many types of baby birds depend on protein-rich caterpillars to make it to adulthood. Carolina Chickadees need 6,000 to 9,000 caterpillars to feed just one nest of chicks. As adults, moths pollinate night-blooming flowers and provide nutrients for birds, bats, lizards, snakes and other insects.

“They’re food for lots of things,” Adams said. “Insects, let’s face it, are at the bottom of the food chain.”

If moths emerge earlier or later than usual, it can result in a mismatch between the insect, the plants they need to survive as caterpillars and species like birds who need them for nutrients.

Some moths are proving elusive. Dominick discovered the Meropleon cinnamicolor moth in the 1960s. He collected many of them, suggesting it was common. The moth was last seen in the 1980s in North Carolina — and not for a lack of trying, LoPresti said.

“We were out almost every day in October and November looking for it,” he said. The moth is a grass feeder, and Dominick noted he caught it right on the edge of the marsh. LoPresti and his students targeted the same habitat with no luck.

“If it’s not extinct, it’s one of the rarest moths in the world,” he said.

It would be nearly impossible to confirm if the moth is extinct. And if the moth is extinct, it also would be impossible to determine why. It could be temperature, or it could be changes in land management, like logging practices or the reintroduction of fire into the ecosystem, LoPresti said.

“It could be that there was a good population there, and then there was a hurricane and it all got flooded out, and they all drowned,” he said.

More likely than not, it’s a combination of reasons, LoPresti said.

As some moths move out, others are moving in. The golden-colored Schinia rufipenna is common in Georgia and Florida but new to the Lowcountry. Dominick found none. Now, they’re abundant in the fall, LoPresti said. 

The biggest mystery is the Maple Spanworm moth. Dominick collected none, even though it’s common wherever there are maple trees. 

“(Dominick) got lots of other maple-feeding moths,” LoPresti said. “It’s a big white moth, he wouldn’t have missed it.” 

Why its showing up now and didn’t back then is puzzling, he said. 

Other newcomers are less mysterious. The Noctua pronuba is a nonnative moth that was introduced from Europe around 1979, likely hitching a ride on imported plants. Dominick wouldn’t have found this moth because it didn’t yet exist in local ecosystems.

The new survey will wrap up in 2028, but LoPresti hopes it won’t stop there.

“Hopefully, someone will repeat this in 50 years or 60 years,” he said.

LoPresti found the most exciting moth of the evening the next morning. Most of the traps he set up were light traps, but he set up a few bait traps, too. These traps use the aroma of rotting fruit to entice moths. LoPresti whips up the concoction himself.

“I put a half can of beer, mash up a bunch of bananas and then add molasses or brown sugar to make it sweet,” he said. “Then, you let it sit for three to four days.”

It was one of these smelly traps that lured a fruit piercing moth, native to the Caribbean. The sight was a total surprise. LoPresti had never collected one before, and Dominick certainly hadn’t.

“It’s not a regular visitor here,” LoPresti said. “It’s not going to reproduce. Its host plants aren’t here.”

How it ended up in a Lowcountry swamp is anyone’s best guess. LoPresti suspected it got caught in winds that pushed it off course. He took the fruit piercing moth back to the lab where he’ll pin it and add it to the growing collection.

“Perhaps in 50 years they will be here more regularly or perhaps permanently,” LoPresti said.

Something will be learned from it, he said.