Females are not the only ones to approach males as they roll their balls away. Rival males constantly challenge one another over ball ownership, and vigorous battles are commonplace. But these fights occur out in the open on the exposed surface of the soil. Furthermore, the objects of these fights—balls of dung—are themselves mobile and malleable. Balls are pushed, pulled, even torn in half during fights as the males tussle around and around, clinging to and scrambling over the rolling balls. (These battles are great fun to watch, incidentally. At the Barro Colorado Field Research Station we'd paint numbers on the backs of rival males and place them on a dung pile centered in the bull's-eye of a horizontal dartboard, betting on the winner and cheering them on as they fought to roll their marble-sized balls out of the ring.) Despite their pugnacity, not one of the thousands of ball-rolling dung beetle species has horns.

Emlen, Douglas J, Animal Weapons_ The Evoluti…, loc. 221