Micromoths in Huge Trouble: The Dwindling Food Source of Hawaii's Philadoria Species

The Philodoria species is well known in Hawaii as micromoths that are roughly the size of a human eyelash. Chris Johns, a biology Ph.D. student of the University of Florida and a National Geographic explorer, has been striving to promote awareness of the plight of this threatened species due to their highly specific diet.

Commonly referred to as leaf miners, the genus Philodoria's moths live inside the leaves of their host plants and burrow around the leaf until they mine their way out when they are about to start metamorphosis. There are 12 different plant species, all endemic to Hawaii, the Philodoria feeds on. However, majority of the Philodoria moth species can only feed on a single species of Hawaiian plant. In recent years, it has been discovered that some of these Hawaiian plants are already endangered.

Until 2013, the Philodoria moth species was thought to have been extinct. Johns was able to rediscover the moth that year and called attention to its dwindling food source through his work Leaf Miners: A Note from the Edge of Conservation.

"It's not typical that you find an organism where each species is so specific but all of the relatives as a whole feed on so many different plants," said Johns in a National Geographic feature. "And we're not entirely sure why that has happened."

After beginning his fieldwork in 2013, Johns has seen the Philodoria caterpillars on all of Hawaii's main islands but he has only seen 30 adult moths. Thanks to their careful research, Johns and his team was able to rediscover two micromoth species that had not been seen or left any recorded trace for over a hundred years.

"Some of the adults we're starting to find, we release back into the wild after capturing and taking a look," shared Johns. "We're starting to feel many of these moths are extremely rare and very vulnerable."

With Hawaii's biodiversity being threatened by ongoing development, invasive species, and changing land use, Johns has included expert botanists and conservationists on his team to locate the rare communities of native plants. He and his team have discovered more than a dozen new micromoth species since 2013, and Johns is hopeful that there are more species waiting to be discovered.