Issoria lathonia is a scarce resident. It has both temporary and permanent populations; permanent populations are practically limited to the dunes, where it is still common, in spite of the moderate decline in the 1990s recorded by the Dutch Monitoring Scheme. It occurs on warm open, dry, grasslands; in the dunes, its larval foodplant Viola curtisii grows in dry, open patches. Temporary populations are nowadays only found inland, on cornfields that have been left fallow. This happens especially after invasions, such as that of 1947 with 3100 inland records. It flies in three generations from mid-April until the beginning of October and in this country, probably hibernates succesfully only as a young caterpillar. At present, the species is categorised as 'vulnerable' on the Red List. Measures should be taken to protect the permanent populations in the dunes: extensive grazing, for example, can help prevent scrub encroachment and keep the vegetation open.
Swaay, C. van, Wynhoff, I., Groenendijk, D., Bos, F., Bosveld, M.
- Bos, F., M. Bosveld, D. Groenendijk, C. van Swaay & I. Wynhoff 2006. De dagvlinders van Nederland, verspreiding en bescherming. Nederlandse Fauna 7. De Vlinderstichting, Wageningen en Nationaal Natuurhistorisch Museum Naturalis, European Invertebrate Survey, Nederland.