Dung beetles guided by Milky Way

Dung beetles manage to maintain straight roll
 paths even on moonless nights

They may be down in the dirt but it seems dung beetles also have their eyes on the stars.

Scientists have shown how the insects will use the Milky Way to orientate themselves as they roll their balls of muck along the ground.

Humans, birds and seals are all known to navigate by the stars. But this could be the first example of an insect doing so.

The study by Marie Dacke is reported in the journal Current Biology.

"The dung beetles are not necessarily rolling with the Milky Way or 90 degrees to it; they can go at any angle to this band of light in the sky. They use it as a reference," the Lund University, Sweden, researcher told BBC News.

Dung beetles like to run in straight lines. When they find a pile of droppings, they shape a small ball and start pushing it away to a safe distance where they can eat it, usually underground.

Getting a good bearing is important because unless the insect rolls a direct course, it risks turning back towards the dung pile where another beetle will almost certainly try to steal its prized ball.

Dr Dacke had previously shown that dung beetles were able to keep a straight line by taking cues from the Sun, the Moon, and even the pattern of polarised light formed around these light sources.

But it was the animals' capacity to maintain course even on clear Moonless nights that intrigued the researcher.