Undoubtedly one of the most commonly noticed insect activities is that of the dung beetles, particularly those rolling dung balls.
There are around 8 000 species of what we call dung beetles, many of which we have in our region. Of the hundreds of different species of dung beetle, our largest one measures up to 50mm in length, while one of the smallest is only around 5mm. They all feed mainly on the dung of mammals.
In this area of the central Lowveld, the most commonly encountered dung beetle usually plops in to surprise your guests at their evening meal. Attracted by the lights, they are often seen at night. Rather smooth shelled, up to 20mm in length and with a purple sheen, they leave a smell on your fingers if picked up. They are dung rollers, useful and harmless, and are one of the 'Plum Dung Beetles which is found along the Limpopo Valley and down the eastern border south to the Eastern Cape.
Some of the well-known species construct balls, which they roll away from competition and predation, to be buried as a food supply or on which they lay an egg. In the latter case the dung ball will supply food for the resulting larva which pupates and grows within the dung ball. With many other species, the dung is carried down below the main supply and buried in burrows. It is either used as a food supply for the adults or eggs are laid in the packed passages where the young will develop as usual.
Next time you have a chance to examine a pile of fresh animal dung, have a look for the various types of dung beetle. You will be surprised how many small, concealed species of various colours there are working away. If you happen to pick one up, look underneath at the leg joints and under the neck area. There are normally many tiny mites that are hitching a ride. They climb aboard from one dropping and catch a lift on that aircraft to the next dropping where they disembark, while others take their turn. The interaction between species is endless and vital in maintaining natural systems.
Piles of animal dung and the workers within form a most valuable source of food for many of our Lowveld animals. Many species of birds can be seen searching for insects and seeds. Mongooses and other insectivores often scratch for insect food.
Dung beetles are able to pick up the scent of any food source from a great distance. To do this they will quarter downwind, flying backwards and forwards across the wind until they pick up the scent. They will then follow the scent upwind direct to the source where they plop directly onto, or near target. They will be quick to locate any fresh dung and can be a useful indicator of the proximity of large animals such as buffalo or elephant, but they can be quite unnerving to a squatter!
In healthy veld conditions, dung beetles will scatter a dung pile in very short time. In the dry season, when the insects are dormant, the dung is often left untouched. This can become an indicator of dry or wet season droppings when assessing the history of an area. Unbroken buffalo and other droppings sitting for years on the soil surface are an indicator of serious soil problems and bad veld conditions. Like all animals, the beetles require moisture, air and food. Without one of these they will perish, so their presence or absence is a valuable veld condition indicator, apart from being an interesting attraction.
Extracts from an article written by Dave Rushworth appearing in the Kruger Park Times newspaper with their kind permission.