There is a single brood, flying through May and early June with a few sometimes emerging in August or later.

The larval food plants are Cowslips and Primroses.

The sexes are similarly marked but the male has only four clearly visible legs as two are very much reduced. The females have wider tawny-orange marks and broader, less pointed wings - these are small differences not easy to notice.

16 May 2014. Bison Hill, Whipsnade. Bright but clouding over. I saw 7 Dukes before the sun disappeared, though more had been seen by a group who were earlier on the scene.