Dung Beetles and Dirty Jobs

When you think of dirty jobs, think of dung beetles. They have the task of cleaning up the savannahs, grasslands, and forests where wild animals live. If you have had the experience of cleaning up after a dog or cat, just think about cleaning up after elephants. A dung beetle can move dung weighing 250 times as much as itself in one night’s work.

There are thousands of species of dung beetles. Some bury the dung where they find it, and some live in it. Others known as rollers take the excrement of elephants and other large animals and roll it into balls. Then they roll the balls to their nests to use as food for themselves and their offspring. They use their back legs to roll the balls, so they are not facing where they are going. Imagine rolling a ball that is larger than you in a straight line without looking where you’re going. So how do they do it?

These beetles can do their cleanup work in the daytime or at night, using the Sun or the Moon to navigate. An African species of dung beetles (Scarabaeus zambesianus) uses polarization patterns from moonlight to chart its direction. Another African species (Scarabaeus satyrus) can stay on course when there is no moonlight. South African researchers using a planetarium for a testing lab found that these beetles can go in a straight line using only the Milky Way on a moonless night. They are the only insects we know of that can use the galaxy to find their directions.

The idea of insects navigating by the Milky Way was a surprise to the scientists. I wonder Who thought of that idea first? (Hint: Perhaps the Designer of insects and the Milky Way.)

— Roland Earnst © 2021