There were large numbers of these very small beetles on the Myoporum insulare on Providence Road adjacent to Woodlands Historic Park. (These were planted by the council and do not occur in the Park.) I believe the enlarged hind tibia identifies it as a flea beetle, tribe Alticini, which narrows it down to one of 232 species according to AFD
I counted 17 individuals of these leaf beetles actively crawling all over a large gum tree, with a few pairs mating. There were also some black eggs laid in formation on several leaves of the same tree, possibly from this species. Five photos uploaded.