Scientists group dung beetles by the way the beetles make a living: rollers, tunnelers, and dwellers. Rollers form a bit of dung into a ball, roll it away, and bury it. The balls they make are either used by the female to lay her eggs in (called a brood ball) or as food for the adults to eat. Tunnelers land on a manure pat and simply dig down into the pat, burying a portion of the dung. Dwellers are content with staying on top of the dung pat to lay their eggs and raise the young.
After a chance encounter at a dung pat, male and female rollers establish a pair bond. The male offers the female a giant-sized brood ball. If she accepts it, they roll it away together or the female rides on top of the ball. They must watch out, though, as other beetles may try to steal their ball!
The new pair finds a soft place to bury the ball before mating. The male then leaves to find more partners. The female stays to make another brood ball or two and lays a single egg in each. She then coats and seals the ball with a mixture of dung, saliva, and her ownfecesand stows it underground. Some dung beetle mothers stay with the ball for two months, cleaning the larvae (called grubs) that hatch and removing their feces.
Tunnelers dive into a cow pile and tunnel straight down to set up the family home. Storing the dung underground keeps it fresh and protects the developing grubs from predators and parasites. The female sorts through dung and arranges it throughout the tunnel. The male’s job is to bring home the doo-doo. One or both of the parents stay with the larvae until they mature, which can take up to four months. This level of parental care is unusual in the insect world.
Dwellers are on top of the world—or at least the dung heap. The female lays her eggs on top of manure piles, and the entire development from egg to adult takes place inside the dung pat. Dwellers are smaller than tunnelers and rollers, and they seem to like cow patties best for raising a family. The adults can be found in fresh, moistdroppings, while the larvae are slowly growing in dung that is drying out.
