Life Trockenrasen: Rock Grayling

The rock grayling is a butterfly that belongs to the Satyrinae family. It is often mistaken for the woodland grayling (Hipparchia fagi) due to their similar appearance, which complicates determining its exact distribution. It is believed to occur from southern France to eastern Europe. In Germany, it is primarily found in Brandenburg and Saxony. The rock grayling prefers open pine forests with clearings on dry, sandy soils. Adjacent dry grasslands and heathlands near pine trees provide an ideal habitat for this species.

Characteristics and Lifestyle

The forewings of the rock grayling  are approximately 3.5 cm long, making them smaller than those of the woodland grayling (Hipparchia fagi). However, distinguishing between the two species is challenging, and 100% certainty requires a genital examination. The upper side of the rock grayling’s wings is brown, featuring whitish bands and an eye-spot at the wingtip, accentuated by an ochre-coloured background. The hindwings are grey-black with a light band and a distinctly jagged edge.
The butterfly can be observed from July to August. Its larvae hibernate in pupal form in burrows within open clearings. To ensure successful hibernation, the butterflies lays their eggs on dry plant material close to potential food plants. The larvae feed on sedges and grasses such as torgrass (Brachypodium pinnatum) and sheep’s fescue (Festuca ovina). In contrast, the adult butterfly favours nectar from blue and violet flowers like sheep’s bit (Jasione montana) and mother-of-thyme (Thymus serpyllum), plants commonly found in the LIFE project areas.

Endangerment

The rock grayling’s population is declining dramatically throughout Germany. Stable populations have been recorded in reclaimed mining areas in the Lusatia region. Decades of lignite mining created open sandy areas where plants that are a food source for butterfly larvae could establish and spread. This highlights the importance of protecting dry grasslands and their plant diversity to support the plants that act as food sources and, in turn, the corresponding butterfly populations.