A small black and silver Sand Wasp (Fam. Crabronidae) that I spotted exploring a sand bank in Capel, in Australia’s SW corner. Possibly she was looking for a good place to excavate a burrow, but she may have been looking for spiders as well.
There are some 145 described species, although many species, especially in South America have yet to be named. Most species are found in the tropics and Southern Hemisphere, and at least a third of the known species are found in Australia. At least one researcher, in 1916, thought this meant they’d been out-competed by more aggressive wasp species in the Northern Hemisphere, but that’s exactly the kind of bullshit conclusion Eurocentric bias can lead you to.
Pison wasps raise their young on a diet of living but paralysed spiders. While many species construct large mud nests in caves or tree hollows, others use hollow plant stems, beetle burrows, abandoned bird nests, or dig their own tunnels. Typically, multiple spiders-and-egg cells will be placed adjacent to one another, with each cell is sealed off from adjoining eggs with mud or dung pellets. Since a number of species will nest inside artificial structures like keyholes, or holes in wood, a few have been widely dispersed by humans.