June 19, 2015
The photo above features a nest of Australian meat ants (Iridomyrmex genus) and their highways. It was taken in the Kosciuszko National Park, adjacent to the Yarrangobilly River in New South Wales. Found throughout Australia, these eusocial insects cover the tops of their nests with pebbles, very small sticks, gravel and sand to speed up the heating of the nest during the morning. Nests containing around 60,000 individuals are generally formed by daughter-queens to the main nest queen and are linked by what are sometimes called highways or foraging trails. These trails are noticeable because debris is cleared by workers leaving a smooth pathway for the ants as they travel to and from satellite nests or on foraging expeditions. The meat ant is the only Australian ant to regularly establish such trails and to maintain them over an extended period. They're known to aggressively protect their nests and trails by approaching any threat en masse. As the main nest grows, so do the satellite nests often resulting in supercolonies extending over 0.5 mi (1 km).
The name meat ant was given by Australian farmers who observed their ability to strip a carcass of meat quickly. They are in fact omnivores and secretions from various insects form a large part of their diet. In addition, meat ants attack and kill other insects and small lizards and have even been known to kill and devour cane toads. The inset at lower right of the photo highlights the level of attention given by the ants to maintain a trail. Photo taken on April 6, 2015.