Ábrahám Levente – Farkas Sándor: Butterflies along the river Drava, 2008

Along river Drava, and especially in its hardwood riverine oak-ash-elm gallery forests, quite significant populations are found of the Natura 2000 listed scarce fritillary (Euphyáryas maturna) [19] and clouded Apollo (Parnassius mnemosyne) [201. Both species have only one generation during one year, and they take wing in late May Caterpillars of scarce fritillary initially feed in caterpillar nests' in the upper canopy of common ash, then when the heat of the summer commences, they drop down to the ground and find shelter in the litter where they will also spend the winter. The followingyear, the caterpillars continue to feed, now solitarily, on various herbaceous plants. The clouded Apollo is similar to whites, but the tip area of its forewings is translucent, pergamenous, lacking any scales.The females have a strikingly large matingappendix. In the Carpathian Basin it is a species of hilly and mountain areas, and in lowlands only isolated, sporadic populations are found. In springtime, its caterpillars feed exclusively on Corydalis plants. Its preferred habitats are moist forests, oak-hornbeam woodlands and hardwood gallery forests. Local extinctions can be caused in both species by habitat drying due to clear cuttings, and by the disappearance of host plants which can result from the uprooting of tree-trunks or the expansion of locust-tree stands.