A second strategy adopted by many dung beetles is tunneling. Females of these species fly into dung and immediately begin to excavate burrows into the soil below. Once they've dug sufficiently deeply—a foot to a yard, depending on the species—they begin pulling pieces of dung down into the tunnels to stash them away from the other dung-feeding insects above. Females may make fifty or more trips to bury sufficient dung to provision just a single egg, and they'll repeat the process for a string of successive eggs. While females are working on this arduous task, male beetles fight among themselves for tunnel ownership. A victorious male will guard the entrance to a tunnel—not so much to keep other species away from the food as to keep rival males of the same species away from the female. While in residence, a male will mate repeatedly with the female, but he will often get kicked out of the tunnel by an intruding, larger male. Males of tunneling species often have horns.

Emlen, Douglas J, Animal Weapons_ The Evoluti…, loc. 222