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
These beetles were identified as Altica pagana by Ken Walker, but have been identified as Diachus auratus by Stephen Thorpe. I feel Diachus auratus is more likely correct as the beetles shone a bronze, golden colour - they were definitely not blue.