My granddaughter and I were out walking in the woods when she spotted what looked like a clod of dirt that appeared to be propelling itself slowly along the trail. When we looked more closely we were lucky enough to see a small beetle hard at work, laboring with all its might like a miniature Sisyphus, to move its prize, a bit of coyote scat, over a clump of grass towards some unknown destination.
Nearly anywhere in the world, if you turn over a cow patty, and perhaps dig an inch or so below the soil, you may find these fascinating creatures at work. They are dung beetles, and they are an important part ecosystems all over the world.
The bigger your ball, the better your chances of attracting a mate.
Dung beetles have an extraordinary ability to detect the odor of their food source, as this quirky BBC video of dung beetles rapidly converging on recently deposited monkey scat shows:
It is a hard thing to wake up in the morning and decide you're suddenly going to go out there and study dung beetles. - Douglas Emlen, Professor of Biology, University of Montana
The dung beetle may move along like a miniature lumbering tortoise, but it inhabits a world filled with sex and violence. Douglas Emlen is a biologist who studies the evolution and development of insect weaponry. In an interview with Terry Gross on Fresh Air, he describes elaborate horns and spines on the males, which are used in fights with rival males, and the care a dung female beetle takes to provide food for the offspring that will hatch from eggs she lays in the underground burrow she constructs.
The females will make 50, 100 different trips down into the ground for every single one of these eggs that she lays. And during this time, the male is guarding that tunnel, keeping everybody else away and mating with the female absolutely as often as he possibly can. And other males come and challenge.
Males use their bodies to block the entrance to the tunnel, using their horns as bars on a jail cell to prevent other males from entering. Meanwhile smaller males may make sneak attacks, going around the guarding males by tunneling parallel to the main tunnel, and then tunneling horizontally into the chamber with the female, mate with her and escape before they are noticed by the male guarding the main tunnel. Who knew dung beetles were so interesting?
Dung beetles are obsessed with dung.
They slurp it, haul it, roll it, fight about it, and bury it...They don't bite or spit or sting. They simple live, eat, sleep and dream dung.- ecologist Pat Richardson
However, it turns out that the dung beetles attraction to dung is good for the environment, and is even financially beneficial to ranchers. According to Texas A&M, dung beetles are highly beneficial insect, so much so that the USDA has worked to introduce dung beetles into pasture lands. In a fact sheet on dung beetles, ecologist Pat Richardson details the benefits dung beetles provide to a healthy ecosystem-
reduced fouling of available forage, breaking life cycle of pest flies and internal parasites (those whose eggs or larvae incubate in dung), improved soil aeration, increased soil organic matter, nitrogen and moisture, increased water infiltration in soil (reduced erosion and flooding), removal of non-point source pollution from the watershed, and improved soil foodweb health (in turn producing healthier vegetation).
Richardson says that dung beetles could save cattle raisers an estimated two billion dollars annually by increasing nitrogen recycling, decreased pests, and improved plant grazing . Unfortunately, because of the use of pesticides, she says that many pasture lands lack dung beetles.
We have two main species in Texas. Phanaeus vindex MacLachlan is actually very pretty, with irridescent green and gold colored bodies. It is easy imagine how they inspired Egyptian scarabs.
Another species found in throughout Texas is Onthophagus gazella Fabricius, introduced in Texas in the 1970's by U.S.D.A. scientists, which breaks down some 80% of cattle droppings in some parts of the state. I think these beetles, seen on our land, are members of this species-
Around here, we frequently see dung beetles working to remove coyote scat from trails, and in the summer, when the beetles are most active, they even act as natural pooper scoopers, cleaning up after Molly, our Labrador Retriever. Now that is what I call a beneficial insect!