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Night music of the ‘lepidopteran lovefest’

August 7, 2012

Photo by Bruce Fellman

National Moth Week guide and moth expert Ryan St. Laurent, a recent Narragansett High grad who’s heading for Cornell, pointing out a pine sphinx caterpillar.

The formal activities connected with National Moth Week, an international lepidopteran lovefest that took place in late July, are now over. But, from the success stories that are being posted on the NMW website—www.nationalmothweek.org—the “celebration of moths and biodiversity” was an unqualified success. “This is just the beginning,” David Moskowitz, NMW co-founder, told me over the phone. “We’re already making plans for next year.”

Data collected at more than 200 moth nights around the world is currently being tabulated, and the hope is that citizen-scientists can help improve range maps for some of the myriad species—there are more than 10,000 in North America alone—of these fascinating critters. If nothing else, NMW has tried to bring moths, which are mostly active at night, to the attention of a public more attuned to butterflies, which, if you’ve wondered about the difference, are basically just moths that work the day shift.

Southern Rhode Island joined the NMW hit parade with an event last Friday, July 27, at the Nature Conservancy’s Francis C. Carter Memorial Preserve in Charlestown. I’m not exactly a stranger to moths—I watch them just about every night at our porch lights—but the moth party at the Carter Preserve gave me a chance to rectify a long-running oversight and finally visit the 10-year-old, 841-acre collection of pine and oak scrub barrens, the centerpiece of which is a splendid 35-acre grassland that is home to the grasshopper sparrow, an exceptionally rare bird in Rhode Island. The event also gave me the opportunity to learn about moths from a remarkable young biologist, Narragansett’s Ryan St. Laurent.

Ryan, who just graduated from Narragansett High School and is about to start his freshman year at Cornell—he’s planning to major in entomology, of course—spent this summer cataloguing the moths that call the Carter Preserve home, so he and refuge manager Tim Mooney were the perfect hosts.

Moths, alas, do not attract quite the following of a competing event—the opening night of the London Summer Olympics—and a torrential downpour in late afternoon also cut down on attendance. But as it began to grow dark and the threat of rain dissipated, a stalwart group of about a dozen, from a young baby in a backpack to a few senior citizens, assembled in the gravel parking area to watch Ryan’s “show and tell” about the species that drew him to Carter in the first place.

From a mesh cage, he withdrew an impressively large, dark moth with a three-to-nearly-four-inch wingspan. “This is called a Pine Devil,” Ryan explained, to the oohs, ahhhs, and “oh wow’s” of the group. “It used to be found in this area in the 1950s, but then it disappeared.”

Since the Pine Devil’s caterpillars feast on pitch and other pines that are found at Carter, one of Ryan’s motivations to census the Preserve was to see if it sheltered a population of Citheronia sepulcralis, one of the members of the giant silkmoth family whose members were inadvertently decimated by the introduction of a parasitic fly called a tachinid. “The fly was brought in to help control the gypsy moth and another introduced problem species called the Browntail moth, and it apparently did a good job,” he said.

Too good. For when Compsilura concinnata, as the fly is known, ran out of its target species, it started to look for new moths to parasitize. The big silkmoth caterpillars were soon on the menu; the impact was rapid and devastating.

To date, Ryan hasn’t spotted any Pine Devils, but, as we would learn later, there is reason to hope that at least some of the silkmoths and other large species have evolved strategies to handle their tormenters. “And even if we don’t spot anything else tonight, at least everyone’s seen something cool,” he said, putting the moth, which he hand-reared, back in its enclosure.

Moth husbandry, it turns out, is often the gateway drug for this breed of lepidopteran addiction. “Someone gave me some cecropia moth eggs when I was seven or eight, and I reared them,” said Ryan, talking about one of the large, showy silkmoths that give lie to any impression that these insects are dull and boring. “The caterpillars got to be the size of hot dogs, and I thought this was so incredible that I just kept rearing these and other species. And here I am, going into entomology.”

At the edge of the Preserve’s grassland section, Ryan set up the main tool of the moth-hunter’s trade—a large sheet and a black light, which, for reasons that remain uncertain, attracts the insects. While he worked, Preserve manager Tim Mooney led us on a fine night walk around the perimeter of the meadow. “We mow it once a year, and we manage the edges of the area to encourage the new growth of pitch pines,” Tim explained. “It’s part of the Nature Conservancy’s global conservation mission to identify and protect the world’s most ecologically important and vulnerable areas—but not just for birds, moths, and butterflies, but also for key places that help sustain the human population.”

As we walked, whippoorwills called intermittently, bats started to work the darkening sky, and the crickets and katydids offered up a little night music. When we got back to the blacklight, Ryan had a number of visitors to show us. One curiosity was a Pearly Wood Nymph. “It’s supposed to look like bird poop,” he said, pointing out an effective strategy to avoid getting eaten. There was a kind of Prominent moth—this one had “furry” feet that resembled those of hobbits—as well as an odd, sickle-shape-winged moth called a hooktip, along with numerous geometrid moths, beetles, mayflies, and adult ant lions.

In the shrubs near the main attraction, Ryan found a white Saltmarsh Tiger Moth that, when he touched it, fell to the ground.

“You killed it,” wailed one of the onlookers.

“No,” Ryan laughed, “they just like to play dead.”

The young biologist then showed us a kind of pine sphinx moth caterpillar that was a dead ringer for the pine needles it fed on. And after a bit more searching, he discovered a Luna Moth caterpillar, which was—uncharacteristically, he said—dining on oak leaves.

“How do you find these? They blend right into the needles and leaves,” marveled a “moth-er.”

“Practice,” Ryan deadpanned. “And you look for clipped leaves.”

What we had hoped to find—one of the silkmoths—didn’t seem interested in the light, but something else clearly was: a huge dark moth that flew overhead, then checked out, at close range, several members of the group.

“It totally likes you,” said one person.

“Just as long as it stays out of my face,” said another.

When it finally landed on the sheet, Ryan identified it as an Elm Sphinx Moth (a.k.a. Four-horned Sphinx, after the horns that its caterpillars bear). It’s even bigger than the Pine Devil, and it drew appreciative comments from the crowd, as it obligingly stayed put for a photo shoot. “This is definitely a treat to see,” said Ryan. “They were never that common in the first place, and they were among the big species getting wiped out by the fly.”

The fact that it was here at all was a good sign, he said. “Hopefully, it means that it’s only a matter of time before the bigger moths do better and start to return.”

If Ryan and Tim have any say in the matter, these splendid insects will have effective champions who will help ensure that the “law of unintended consequences” doesn’t rear its unexpected head and will also fight for good habitat that will support moths of all persuasions. NMW events like the one at the Carter Preserve will help mint a new group of moth partisans happy to watch and defend the butterflies that work the night shift.

 

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