The Industrious Dung Beetle of South Africa
April 03, 2020
Photographer: Patti Weeks
Summary Author: Patti Weeks
The peculiar behavior of the dung beetle — gathering, rolling and feeding on animal excrement —serves several important functions: cleaning up the environment, therefore reducing parasites, fertilizing the soil once the dung is buried, and providing a food source for its larvae. At least 6,000 species of dung beetles are found worldwide, on all continents except Antarctica. Scientists have recently discovered evidence that dung beetles have an evolutionary link to the dinosaurs, beginning in the Lower Cretaceous Period (145-100 million years ago.)
The dung beetle pictured here (Scarabaeus lamarcki), is classified as a ball roller, or a telocoprid, and is found in the savanna region of South Africa. Thousands of beetles will descend upon a fresh pile of animal feces. A male creates a ball, and using his strong front legs against the ground, pushes the ball (up to 50 times his weight) backward with his back legs in a straight line—as quickly as possible to avoid thievery by a kleptocoprid dung beetle. He excretes a pheromone to attract a female, who attaches and clings to the ball as the male continues to push it in search of soft soil. The couple uses their shovel-shaped heads to dig a hole and bury the ball. The female lays one egg in this brood ball, and the developing larva uses the dung as sustenance. The couple can repeat this process and bury up to three balls in a single hole. The outside of the buried ball hardens with dung and soil as a protective layer for the larva. However, before the larva metamorphoses, sometimes a honey badger can sniff out a buried ball, dig it up and consume the grub as a tasty treat. The second photo shows one of the rangers on my recent safari in the Waterberg Biosphere of South Africa, holding the core of a dung ball broached by a honey badger.
While it may appear that dung beetles are going blindly backward nowhere fast, they’re actually using a variety of celestial compass cues to help them move in a straight line. Dung beetles have photoreceptors in their eyes that allow them to see patterns of symmetrical polarized light around the Sun, and after sunset, they use the Moon, stars and possibly even the Milky Way for orientation. If obstacles throw a beetle off his path, he’ll climb atop his ball and do a dance, taking a snapshot of the sky for reorientation, then continue rolling. Photos were taken in mid-December 2019.
Photo Details: Top - SONY DSC-RX10 IV camera; 220 mm focal length; f/4; 1/400 second exposure; ISO 100. Bottom - Same except 6 mm focal length; f/2; 1/417 sec. exposure; ISO 20.