World wide there are over 20,000 species in the Scarabaeidae family, 300 in Europe, and 89 in the British Isles. Of these there are about 5000 species of dung beetle in the world, and over 50 species in Britain, but none of the British species are dung rollers, i. e. none of them break off a ball of dung and roll it off over the ground as the famous Egyptian beetles do. Dung beetles range in size from 0.2 - 17 cm. The other beetles in the Scarabidae family are the plant-eating chafers.
Below is Aphodius sp. showing the typical adult dung beetle shape - the strong, digging legs, shovel-like head good for moving earth and dung, and lamellate antennae with the plates at the end that can open up better to locate any scent molecules of fresh dung.
Dung beetles perform a very necessary service to us humans with our ever increasing consumption of meat. For example, in the U. S. there is almost 1 cow for every 3 people. Each cow produces about 9 tonnes of dung a year! And how do we get rid of this dung? Well for cows reared outside we do nothing at all. The dung beetles and other invertebrates perform that service for us for free.
When dung beetles bury dung they not only remove it from the surface of the soil, but by burying it they allow the dung to fertilise the soil better, and the tunnels they dig aerates the soil too. One elephant dropping can attract as many as 16,000 dung beetles; 4000 within the first 15 minutes!
In Australia there are no native dung beetles, and after the introduction of cattle in the 19th century there was a massive fly population explosion because of all the piles of dung lying around for months on end. So they introduced a South African dung beetle. This greatly reduced fly numbers, which pleased both cattle and humans.
The ancient Egyptians associated the dung ball rolling behaviour of the adult beetles with their sun god, Ra, or Khepera, whom they believed rolled the sun across the sky, consequently dung beetles were venerated in their culture. Dung beetles were also associated with Atum, the creator god of eternal life and resurrection. As the adult beetles would emerge from the buried balls of dung, the ancient Egyptians believed that by burying human dead, the humans would rise again too. Even today the image of the adult scarab beetle in jewellery is supposed to bring good luck to the buyer and wearer.
Though beetles in the Geotrupes genus are large and heavy-looking they can and do fly both during the night and day.
The adults emerge from the soil on warm nights and take flight in search of dung. The beetle above was found lying dead on some steps in Rhodes. It is probably Geotrupes stercorosus, a dung scarabid commonly found on the island, and all over Europe. Adults are 14 - 20 mm long, black or blue/black with a metallic blue or green sheen.
The adults mate in spring then the male and female dig a tunnel below the dung (they prefer the dung of herbivorous mammals, and work fast enough to bury almost a whole cow pat in a single night).
The tunnel is around 40 - 60 cm deep and branches at the end into 4 - 6 chambers. In each chamber an egg is laid. Then the adults drag dung down and fill the chamber with it.
The parents supply the growing larva with fresh dung. The larvae usually take just over a year to develop, so the lifecycle takes 2 years. Geotrupes adults also dig shallower tunnels to store dung for their own consumption. They will also eat rotting fungi.