Wet weather in summer means all sorts of wasps are flying about, looking for caves, overhangs and sheltered spots in which to build their paper or mud nests (see the December 2010 post, ‘A mother’s love‘). Some are even coming to the birdbath on the back deck to sip water.
According to the CSIRO (http://www.csiro.au/resources/MudWasps.html), they are harmless to humans and solitary – though will sting if provoked – and Australia’s largest wasp (up to 40 mm). The single female builds a nest of mud (in my case, up near the bathroom ceiling). The nest contains up to eight cells. The female wasp catches, stings and paralyses it a caterpillar. She then carries it back to the nest, lays an egg on it and seals the cell. The wasp grub hatches, consumes the live food provided and pupates in the cell. After it turns into an the adult, it chews its way out of the cell. Adults feed on nectar and drink water. Other species may take spiders and insects for their nest.
The female is supposed to guard the nest actively, but mine disappeared and has not been seen for a week or so. Perhaps she’s been eaten.
You can find a detailed scientific paper about these wasps at http://www.hindawi.com/journals/psyche/2009/851694.html