Robertson’s Brown 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 Nymphalidae

Nymphalidae

The Nymphalidae is a family of about 5,000 species of butterflies which are distributed throughout most of the world. These are usually medium sized to large butterflies. Most species have a reduced pair of forelegs and many hold their colourful wings flat when resting. They are also called...

 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...

, in the northern Cape, the southern part of the Orange Free State

Orange Free State

The Orange Free State was an independent Boer republic in southern Africa during the second half of the 19th century, and later a British colony and a province of the Union of South Africa. It is the historical precursor to the present-day Free State province...

, the northern part of the western Cape and the eastern Cape.

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 38-40 mm. Adults are on wing from August to March. There are probably multiple generations per year.

The larvae feed on Poaceae

Poaceae

The Poaceae is a large and nearly ubiquitous family of flowering plants. Members of this family are commonly called grasses, although the term "grass" is also applied to plants that are not in the Poaceae lineage, including the rushes and sedges...

 grasses. Larvae have also been reared on Ehrharta erecta

Ehrharta erecta

Ehrharta erecta is a species of grass also known as panic veldtgrass. The species is native to Southern Africa and Yemen. It is a documented invasive species in the United States, New Zealand, Australia, southern Europe, and China....

.