National Museum of Natural History

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2021-07-22 18:00:05

For more than a decade, an enormous group of itty-bitty insects has stirred up playful debate among those who study them. The question nobody could answer: which moth is the smallest of them all? Now, after years of meticulously measuring 2,800 specimens from over 650 species of micro-moths, a group of curious researchers has finally awarded one species the coveted title.

“Everybody always talks about the largest butterfly or the largest moth,” said Alma Solis, an entomologist at the USDA and curator of snout moths at the Smithsonian’s National Museum of Natural History. “But nobody had ever asked ‘which is the smallest?’”

In a new study published in Zootaxa, Solis and an international team of lepidopterists — or people who study butterflies and moths — gave the “tiniest moth on Earth” award to the pygmy sorrel moth (Johanssoniella acetosae), a relatively rare species found throughout Europe. Though small in stature, micro-moth populations can have big impacts on agriculture and the myriad animals that rely on them for food.

The pygmy sorrel moth belongs to a group of micro-moths called leaf miners. Named for their eating habits as larvae, leaf miner caterpillars tunnel between the top and bottom layers of leaves, “mining” them and slurping down the green goodness within. As the larvae eat their host plants from the inside, they create squiggly brown tunnels filled with poop, or frass, scrawled across the leaves. Researchers are often able to identify pygmy sorrel moths by their larvae's distinctive, spiral mining pattern.