In Okinawa, 31 out of 36 examined nests of the weaver ant, Polyrhachis dives, (86.1%) contained multiple queens. The number of queens ranged from 0 to 594 with a mean of 44.6. Such polygyny seemed to be attained by retention of new queens in the mother nests, while adoption of new queens in alien nests might be rare or absent. Adjacent nests frequently exchanged colony members with each other, forming a huge polycalic colony which contained a million workers. Further, no aggressive behaviors or only weak ones were observed between workers from different colonies 1.5 and 40 km apart from each other.