Dung Beetles Navigate Using Milky Way: Study

A new study finds that dung beetles navigate using the Milky Way, as they roll up their balls of excrement along the ground.

Whenever dung beetles find excrement, they shape them into small balls to feed their young. The beetles move the balls, weighing 50 times more than their own bodies, along straight paths to an underground place. Moving in straight lines is crucial to dung beetles, as they need to move quickly to avoid competition from other beetles.

Earlier studies have already shown that dung beetles use celestial compass cues such as the sun, the moon, and the pattern of polarized light formed around these light sources to enable them to orient along straight paths. But it remained unknown as to how the dung beetles managed to navigate in straight lines at night. To find out, a team of researchers led by Marie Dacke, from Lund University in Sweden, studied the nocturnal African dung beetle Scarabaeus satyru.

Dacke and her colleagues moved the beetles from a game farm in South Africa to the Johannesburg planetarium, and observed the insects' reaction in situations like a starry sky and a sky showing only the Milky Way. They found that the beetles were able to move their balls in straight lines in both the situations.

To confirm the results, the research team placed small cardboard hats on some of the beetles' heads so as to block their view of the sky. They found that the beetles took a longer route to complete their task, suggesting that dung beetles rely on the Milky Way to navigate. While birds and humans are known to navigate by the stars, this new discovery is the first evidence of an insect doing so.

The findings of the study appear in the journal Current Biology.