Zerynthia polyxena, the southern festoon, is a butterfly belonging to the butterfly family Papilionidae.
These rare butterflies can be found in warm, sunny and open places such as grassy herb-rich meadows, vineyards, river banks, wetlands, cultivated areas, brushy places, wasteland, rocky cliffs and karst terrains, at an elevation of from 0 to 1,700 metres above sea level but usually below 900 metres.
It is an early spring butterfly. Adults fly from April to June in a single brood. The adults are active for no more than three weeks. The females lay their eggs singly or in small groups at the bottom of the host plants. When found in the wild they prefer to live and lay their eggs in densely vegetated areas, and there is a positive correlation between number of leaves on the host plant and number of eggs laid by females. The eggs are spherical and whitish at first, bluish colored before hatching. The caterpillars feed on birthworts (mainly (Aristolochia clematitis, Aristolochia rotunda, Aristolochia pistolochia, Aristolochia pallida). The special food of the larvae provides the toxic substances which then also go to the adults, making them unpalatable. The young caterpillars feed at first on flowers and young shoots, while after the second molt they feed on leaves. The pupae stay linked to a support by a silk belt for wintering and the new adults hatch the next spring.
