Chequered Cuckoo Bee
The female Chequered Cuckoo Bee Thyreus caeruleopunctatus seeks out the burrow nests of the Blue-banded Bee Amegilla cingulata, and lays an egg into a partly completed brood cell while it is unguarded. The larval cuckoo bee then consumes the larder and later emerges from the cell.
This one was in my garden.
It can be distinguished from the very similar-looking Neon Cuckoo Bee by the pattern of the stripes on the abdomen.