This is one of the last Lapland species of which I haven't managed to get rearing material despite of several desperate attempts (never trust on virgins!;-). According to the great "Lebensräume" series, the Alpine populations feed on Potentilla, accepting Fragaria in rearings. Unfortunately, I haven't found any ova on Potentilla, which are abundant in Saana. I also tend to believe that Dryas would be the main host (at least in FI), as suggested by Panu (I have tried to find eggs on Dryas without success, but it's an immense labour to dig those bloody bushes).
Finland, EnL: Saana, Leg: K. Silvonen
Photo: 21 July 1996 © Kimmo Silvonen