Ecological and behavioural observations of a nesting aggregation of the endemic Tasmanian Digger Wasp Williamsita tasmanica

The endemic Tasmanian Digger Wasp Williamsita tasmanica is only known from 13 registered museum specimens, with little recorded on its life history. A nesting aggregation of females was observed over a 25-day period, enabling the first detailed observations of host log, nest design, prey and egg deposition, and behavioural patterns to be made. Cells were provisioned with large flies (order Diptera) of nine species from nine genera and four families to observe behaviour. This aggregation used a large eucalypt with an exposed core of friable brown rot for nesting. Our study showed that the day-to-day behaviour of the female is predictable, centring on nest construction, hunting large flies and egg-laying. This information has been lodged on the Atlas of Living Australia and voucher specimens collected for the Queen Victoria Museum and Art Gallery to facilitate further taxonomic study.