From the Vlinderstichting in the Netherlands:
On Bemelerberg mountain in the south of Limburg province, and in the immediate vicinity of that mountain, hundreds of Glanville fritillaries are flying right now. This rare butterfly species had virtually disappeared from the Netherlands, but in recent years it became again present in this nature reserve of the Limburgs Landschap Foundation, this year in large numbers.
See also here.
Tropical butterfly photos: here.