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Prowling Hawai‘i Volcanoes National Park in Search of Tiny Moths—and Evolutionary Clues

Like Darwin’s finches, Chris A. Johns’s newly discovered insects tell a story, still unfolding, of Hawaii’s island evolution.

In a fern-clogged swath of Hawaiian forest, a helicopter touches down in a tiny clearing scarcely wider than its rotors. A biologist and two plant experts leap out, crouch, and wait as the craft lifts and speeds away, its loud throb receding in the distance. The team is here in the high cloud forest, known to native Hawaiians as wao akua, the realm of the gods, to bushwhack in search of extremely rare, endangered plants found only in Hawaii. Inside the leaves of these plants, they’re hoping to find something even more difficult to spot: the caterpillars of a tiny leaf-mining moth, Philodoria, which is about the size of an eyelash.

“It’s risky business for sure, but it allows us to get into some places that we would not be able to get to otherwise,” says Chris A. Johns, 28, a Ph.D. candidate in biology at the University of Florida who is writing his thesis about these rare moths. “And in most cases, that’s the only place where a lot of the plants that Philodoria likes still live.”

Like many creatures in Hawaii, the moths are endemic to the islands, and each of the 30 species of Philodoria feeds on only one specific host plant. Many of the host plants are endangered, some critically, with fewer than 50 individuals remaining. With the help of local plant experts, landowners, conservationists, and his advisor, University of Florida researcher Akito Kawahara, Johns is working on a monumental multiyear project to find all of the host plants that Philodoria moths dine upon and collect their caterpillars. Then, with the help of genetic testing, Johns aims to create a family tree of these highly adapted moths, which could offer clues as to how they colonized the islands and branched out into different species.

“It presents this interesting system because you can study how the moths’ preferences for certain plants shift, and how insects come to feed on a wide system of plants over time,” says Johns, a National Geographic Young Explorer. “Hawaii is often described as a natural laboratory. Because you know the exact age of the islands, you can tell the story of evolution on a really particular timescale.”

The work requires nerve-fraying travel in some of the islands’ most remote places—thick forests where few people have ever stepped foot—including some of the most isolated, pristine areas of Haleakalā and Hawai‘i Volcanoes National Parks, which provide special permits for researchers who hike long distances to access them.

“You say hiking, but hiking doesn’t really apply,” says Johns. “It’s a lot of falling and crawling and stumbling and just leaning on branches.” Occasionally they must rappel off crumbling cliffs to get to plants that only live in the vertical world. And often, they strike out, not finding the plants—or finding the plants but not the moths.

But they also make great finds. Johns has already identified several species new to science and is busy describing them with the help of a taxonomist who specializes in tiny leaf-mining moths. And the sweat and effort often lead to remarkable places, such as high forests where moss covers all the trees, fog constantly rolls in and out, and the ground is so soft that the trees move as the researchers hike through. “It’s a really surreal experience,” says Johns.

The hope is that the research will lay the groundwork for the conservation of rare plants and insects. If you don’t know what’s out there, after all, it’s hard to conserve it.

“To me, just knowing that something out there has this story and is so small and humans are never going to see it for the most part, I think it helps illustrate this idea that we don’t know everything about the Earth,” says Johns. “I find that a really beautiful idea, and that in itself is a good reason why these things are important to conserve.”

Desired Superpower: “I watched Ant-Man yesterday and I think being able to be supersmall would be amazing. There are so many things that are happening at that scale that are difficult for humans to perceive or empathize with. I’d like to be there watching a Philodoria moth feed … as long as I wasn’t the plant tissue.”

Essential Field Item: “My big Danner hiking boots. I don’t know how people skimp on good boots. Mine are waterproof and that’s really important in Hawaii when you’re walking over a lot of different terrain and through different temperatures.”

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