UCD Discovery: Smallest Moth in the World?

By Kathy Keatley Garvey

It could very well be the smallest moth in the world.

Senior museum scientist Steve Heydon of the Bohart Museum of Entomology, University of California, Davis, was sorting through his collection of unmounted insects from the Democratic Republic of the Congo, central Africa, when he noticed a moth about 1mm long, the size of the period at the end of this sentence.

The moth is a new species, yet to be described, Heydon said. “We don’t even know what genus it is. We are guessing it is a  Nepticulidae since this family contains the smallest moths. Their caterpillars are leafminers--they actually live between the top and bottom layers of a leaf, eating out the middle.”

 “It has a wing span of 2 to 2.5mm,” Heydon said.  “Insects that have a wing span of 3mm are considered tiny, but this one is really tiny—the smallest moth anyone ever seems to have found.”  An employee of the Bohart Museum since 1990, Heydon has worked with wasps, beetles, flies and other insects “about that small, but never a moth that small until now.”

Heydon collected the moth in April of 2006 on an expedition to the village of Kikongo Mission, located about 45 minutes by air east of  Kinshasa, the capital of the Democratic Republic of the Congo. He caught the moth on forested land, near a river, in a Malaise trap, a mesh tentlike structure commonly used to trap flying insects such as flies and wasps.

“I’ve been sorting and mounting the specimens ever since (April 2006) and I’m almost finished,” Heydon said this week. As he was nearing the completion of the six-year project, a routine look at a sample through the microscope yielded the unexpected—the “smallest-of-the-small” moths. And then, peering through the microscope, he discovered two more just like it.  “So I actually have three specimens of that moth.”

“I don’t know how he could have even seen that,” marveled Bohart Museum junior specialist Andrew Richards, who photographed it.

Moth expert Jerry Powell, emeritus professor at UC Berkeley and director emeritus of the Essig Museum of Entomology, said the specimen may be related to Stigmella (genus) of Nepticulidae.

Heydon, who has a doctorate in entomology, was at the Kikongo Mission at the invitation of former UC Davis students Sarah Stevenson and her college roommate, Marcie Chapman, whose father is a missionary at the Kikongo Mission. Sarah Stevenson, now Woodruff, worked with Heydon at the Bohart Museum in 2006.

The expedition not only served as a collection trip, with about 30,000 specimens added to the Bohart museum collection, but as a conservation and educational undertaking as well.

Moths, like butterflies, belong to the order Lepidoptera. Scientists estimate the number of described species of moths throughout the world at 160,000 or 10 times the number of butterfly species. Most moths are nocturnal, that is, they’re active at night.

 As for naming rights, that will be up to the lepidopterist who describes the moth, Heydon commented.  “We’re waiting for somebody to be interested in this tiny moth. Anyone willing to describe it can name it.”

The Bohart Museum, directed by Lynn Kimsey, professor of entomology at UC Davis, houses a global collection of more than seven million insect specimens and is the seventh largest insect collection in North America. It is also the home of the California Insect Survey, a storehouse of the insect biodiversity. Noted entomologist Richard M. Bohart (1913-2007) founded the museum in 1946.

The Bohart Museum is located  in room 1124 of Academic Surge, corner of La Rue Road and Crocker Lane (formerly California Avenue). Regular hours are from 9 a.m. to noon and from 1 to 5 p.m., Monday through Thursday.  It is closed to the public on Fridays and on major holidays. Admission is free.