18-9-2017 ADOR, VALENCIA - COMMON GERANIUM BRONZE BUTTERFLY (Cacyreus marshalli)

The geranium bronze or brun des pélargoniums in French (Cacyreus marshalli), is a butterfly in the family Lycaenidae.

The geranium bronze butterfly is native to South Africa. The butterfly was first introduced to Europe in the late 20th century, where it has quickly spread to many southern and eastern European regions. Since its introduction to Europe, the geranium bronze butterfly has become a pest to cultivated Pelargonium and Geranium plant species. Currently, efforts are being made to contain the spread of the geranium bronze butterflies as well as to determine the most effective pesticide for the species.

The adult geranium bronze butterfly's wingspan ranges from 15–23 mm in males and 18–23 mm in females. The wings are brown/bronze with a white border outlining the wings. The underside is a grey-brown with darker bands interlaced with white, creating an intricate pattern. The hindwings contain an eye spot in order to divert predators from attacking. The male and female are similar in appearance.

The geranium bronze was first recorded in regions of South Africa, including KwaZulu-Natal and the Cape Provinces, as well as in neighbouring countries such as Eswatini, Botswana, Zimbabwe, Lesotho, and Mozambique. It was accidentally brought to Europe in 1978. After being recorded in England, a colony of geranium bronze was soon found in Mallorca in 1990, and has since spread to most of the regions in southern Europe. In 1996, the geranium bronze butterfly was first recorded in Rome, Italy, and rapidly spread along the Adriatic and Tyrrhenian coastal areas before extending inland. The geranium bronze butterfly now has established colonies in Belgium, Germany, the Netherlands, Italy, France, Greece, Malta, Spain, Portugal, southern Switzerland, Slovenia, Croatia, and the French Mediterranean. The first record of the species in Palestine was made in the garden of the Palestine Museum of Natural History.

Adults are on wing year-round in warmer areas, but usually from August to May in South Africa. At higher altitudes, adults are on wing in December and January.

Geranium bronze have spread from their native regions of South Africa to numerous southern and eastern European regions. This was likely due to accidental transportation of plants infested with geranium bronze larvae and not due to any natural migration patterns. The geranium bronze butterflies fly for short periods of time and frequently rest.