The world's most social beetle

Nearly all eusocial insects are ants, bees, wasps or termites. A few thrips and aphids also live this way. Although beetles are the largest insect group of all, with about 400,000 named species, making up a quarter of insect species, only the horizontal borer is known to be eusocial. Reddish-brown and tiny (six millimetres long, two millimetres wide), it looks rather plain, not one to catch your eye. But it qualifies as one of Australia’s most fascinating (and secretive) creatures, with much to reveal about the origins of social behaviour.