Spialia sertorius

Description

Spialia sertorius, the red-underwing skipper, is a butterfly of the family Hesperiidae. It is found in southern and central Europe and North Africa. This is a species of mountainous regions, being found in Europe at altitudes of up to 1400 m. The wingspan is 22–26 mm. The butterfly flies from April to August depending on the location. There are usually two generations per year, adults of the second generation being smaller than those of the first. This is a variable species but can usually be distinguished from similar species such as Spialia orbifer by the dark reddish-brown colour of the underside of the hindwing. The upper side of the wings are dark brown with small white spots. The larvae feed on Sanguisorba (including Sanguisorba minor), Rubus (including Rubus idaeus) and Potentilla (including Potentilla verna).