The African Grass (or Sooty) Blue, with wings no bigger than a finger-nail.. As Steve Woodhall mentions this must be one of our most common garden butterflies because of the frequency of the invasive Oxalis corniculata, one of its foodplants, in our gardens. The male has a striking iridescent blue upper side compared with the female's bronze sheen with just some basal blue. Characteristically, they will flutter low over the lawn, settle, then slowly open their wings to warm up in the sun.
The genus Zizeeria Chapman 1910. The species from Lycaena knysna Trimen 1862. It has a wide distribution over Africa into Spain where it overlaps with th only other species of the genus Z. kasandra that extends east over to Australia.
Incidentally, sp. knysna is named after the river and town on the Garden Route, aptly called after the Khoikhoi word meaning "ferns," (source Wiki.)