Megachile aurifrons is a very large resin bee. They are black with lines of white hairs, a ginger toupee and red eyes. Loudly buzzing as it flies past, you could be forgiven for thinking one was a blowfly.
This month they have found the nesting block I built. After choosing an appropriate hole, a bee will lay an egg and then cover the hole with resin. They're currently making bright green resin by chewing up wattle (Acacia) leaves.
While the bee is collecting resin, parasitic wasps duck in to lay their own eggs in the hole. If successful, the bee egg/larva will become food for a newly hatched wasp. Ants and skinks also help themselves to bee eggs if they have the chance.
In a single trip to the nesting block, the bee lays eggs in some holes and fills others, so hopefully some will escape the predators.
Making a nesting block
Adding resin to the nest
To make your own nesting block, you will need a chunk of untreated wood. Drill a series of holes of different diameters and depths. Let the drill bit spin at the end to smooth the inside of the hole. The various hole sizes should appeal to different species of bee. I've had a few resin bee species, as well as some Hylaeus species, which cover the holes with something resembling cellophane, rather than resin.