Halictine social evolution: the Australian enigma.

Australian halictines belong to the primitive genus Lasioglossum or related subgenera. The underground nests have lined cells in series or clusters and sometimes at the end of laterals. Two full generations per year are produced in the communal nests. Overwintered and newly emerged females form unique "pseudosocieties" rather than matrifilial societies along Holarctic patterns. Several Chilalictus species produce a "male caste" of big-headed, flightless males, in addition to normal individuals. Oviposition of unfertilized eggs on large pollen balls causes such allometric bees.