NEW YORK—A new bee is buzzing in Brooklyn: The tiny insect, the size of a sesame seed, sips the sweet nectar of the city—sweat.

"They use humans as a salt lick," said entomologist John Ascher, who netted the first known specimen of the species in 2010 while strolling in Brooklyn's Prospect Park near his home. "They land on your arm and lap up the sweat."

North America is home to thousands of species of native bees. But they have long been overshadowed by imported honeybees, prized for their honey and beeswax since the time of the Pharaohs and a mainstay of commercial agriculture. Now, native bees are generating serious buzz.

For Mr. Ascher, 41 years old, nothing quite brightens the day like a new box of unidentified bees landing on his desk from some distant glade. So puzzling was the greenish-blue city bee he netted, though, that it took Mr. Ascher, who oversees a digital catalog of 700,000 bee specimens at the American Museum of Natural History, months to pinpoint its proper place in the insect kingdom.

In the end, only DNA testing by sweat bee specialist Jason Gibbs at Cornell University could identify its niche. Last November, they announced the discovery of Lasioglossum gotham, in a peer-reviewed journal called Zootaxa. The newbie joined the growing catalog of easily overlooked wild native bees.