Robertson’s Blue is a butterfly

Butterfly

A butterfly is a mainly day-flying insect of the order Lepidoptera, which includes the butterflies and moths. Like other holometabolous insects, the butterfly's life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal. Butterflies have large, often brightly coloured...

 of the Lycaenidae

Lycaenidae

The Lycaenidae are the second-largest family of butterflies, with about 6000 species worldwide, whose members are also called gossamer-winged butterflies...

 family. It is found in South Africa

South Africa

The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

, from the West Cape to the East Cape. It is also found in the Orange Free State and possibly in Gauteng.

The wingspan

Wingspan

The wingspan of an airplane or a bird, is the distance from one wingtip to the other wingtip. For example, the Boeing 777 has a wingspan of about ; and a Wandering Albatross caught in 1965 had a wingspan of , the official record for a living bird.The term wingspan, more technically extent, is...

 is 28-32 mm for males and 29-33 mm for females. Adults are on wing from November to February. There is one extended generation per year.

The larvae feed on Selago

Selago

Selago is a genus of plant in family Scrophulariaceae. It contains the following species :* Selago lepida, Hilliard* Selago nachtigalii, Rolfe...

 species, including Selago serrata. Third and later instar larvae feed on the brood of Camponotus niveosetus ants.