Bornean Queenless Ant

Workers are matt black and measure roughly 9–13 mm long, with a distinctly ridged, sculpted body surface — the source of the species name "rugosum," Latin for "wrinkled" or "ridged." The most telling feature is a pair of small bumps on the mesosoma called gemmae, vestigial remnants of wings. Every worker is born with these gemmae, because the species has no separate winged queen caste at all.

The genus Diacamma ranges broadly from India to Australia, covering nearly all of Southeast Asia including Thailand, and is split into roughly 20 regional subspecies. Diacamma rugosum itself is most established across Sundaland (Borneo and neighboring islands), living on the floor of humid tropical forest. Colonies nest in soil, under rotting logs, or at the base of trees, and workers forage mainly on the ground (epigaeic), hunting through leaf litter and decaying wood.

The main challenge is temperament — this species is defensive and carries a ponerine sting strong enough to be genuinely painful, used both for hunting and self-defense, so care is needed when opening the nest or feeding. Because there's no separate queen caste, keepers also need to understand that any worker carries the potential to become the next gamergate, which makes colony management a little different from species with a conventional queen. Better suited to keepers with some prior experience than to total beginners.

Good to Know

The English common name for this ant group, "queenless ant" (or "Bornean queenless ant"), describes its social system literally. Myrmecologists use Diacamma as a model system for studying the evolution of caste and social hierarchy in insects, since every worker starts out with equal genetic potential to become the colony's sole reproductive — unlike most ants, where queen and worker castes are fixed from the larval stage.

Diacamma rugosum has never had a queen — every colony is ruled by a single mated worker called a gamergate.

With no queen caste, colony reproduction falls entirely to one gamergate: the first worker to successfully mate with a male. Mating happens right beside the nest, with no nuptial flight at all. Once she becomes the gamergate, she maintains her monopoly by biting off the gemmae of her rival workers, permanently disqualifying them from ever mating. The gamergate title only changes hands when she dies of natural causes — at which point the remaining workers settle the succession through ritualized antennal duels.

D. rugosum is a committed predator. Its diet should center on live or freshly killed insects — crickets, roaches, fruit flies — supplemented with diluted honey or sugar water. Ideal temperature is around 24–29°C with humidity of 60–80%. Colony founding is semi-claustral: the founding worker forages for herself while raising the first brood, rather than sealing herself away and starving like many other ant species. Growth is fairly slow, and mature colonies typically stay modest in size, at around 50–300 workers — a normal, commonly seen size, not a maximum.