July 15, 2008—Even with 28 million insect specimens in their collection, experts at London's Natural History Museum haven't found a match for a mysterious bug—pictured above—found in their own backyard.

Since it was discovered last year by entomologist Max Barclay, the tiny, red-and-black, seed-eating ground bug has become the most common insect in the museum's wildlife garden.

It has also been spotted elsewhere in the city.

"Today we've had people ringing us up saying they've known about this thing in [central] London for six or seven years," Barclay said.

"It's only when it gets to somewhere like the Natural History Museum, where there are loads of specialists hanging around, that somebody will pick it up."

While the insect looks similar to a Central European species, Arocatus roeselii, it is a darker red and lives on plane trees—what Americans call sycamores—instead of alders.

It also resembles a mystery insect found in France that likely isn't native to Europe at all, Barclay said.

"It's also very similar to a common North American pest called the boxelder bug, but it isn't that," he added.

Barclay believes the ground bug either represents a variation of a known exotic species or it's a newly discovered species.

Museum scientists hope an analysis of the insect's DNA will finally solve the mystery.

—James Owen in London