The Silver Arrowhead or Hooked Copper (Phasis thero) is a butterfly of the Lycaenidae family. It is found in South Africa. The wingspan is 31–46 mm for males and 38–47 mm females. Adults of ssp. thero are on wing from September to November and again from March to May in two generations. Adults of ssp. cedarbergae are on wing from October to November and probably also in autumn. The larvae feed on Rhus undulata and Melianthus major. Larvae have been found inside hollow stems of their food plant, but also in nests of Cremogaster peringueyi ants at the base of these stems.