This Cuckoo wasp was blue and was slightly larger than the green Cuckoo wasp in the next observation. The photos were taken around about the same time, of Cuckoo wasps on the fence post that has had holes drilled in it for bees and wasps to use for nest sites.
This tiny little bee has been identified as Hylaeus Gnathoprosopis euxanthus by Bernhard Jacobi. Although tiny and black, its large yellow 'collar' and yellow 'knees' made it look distinctive. The antennae look to be a reddish colour.