the spring weather in the mountains. After winters with little snow and extremely warm springs, the phenological maximum was already reached at the end of May. In Bavaria, significantly more individuals have been observed in odd years than in even years. P. andromedae has a rapid flight, low over the ground. The imagos use various plants as sources of nectar and can also be found in subalpine tall herbaceous meadows, fatty willows or spring swamps when visiting flowers. They use stones, open soil or exposed leaves as seats. The males move into territories to find a partner, preferably on the banks of a stream or in tall herbaceous meadows. For reproduction, P. andromedae needs well-sunlit stands of Dryas octopetala, which is probably the only host plant. This mainly grows on shallow, humus-poor, base-rich stone and rock soils and is also considered a pioneer species of dormant rock rubble heaps. To lay eggs, the female looks for a suitable leaf with a curved abdomen and attaches the egg individually to the underside of the leaf. The great importance of Dryas octopetala as an egg-laying and host plant for P. andromedae was only recognized recently. For a long time, incorrect information about egg-laying and host plants such as cinquefoil species (Potentilla spp.) was spread, as the pre-imaginal stages or the imagos were probably confused with those of other Pyrgus species (especially Pyrgus cacaliae). The information on mallow (Malva spp.) or Alchemilla spp. is also unreliable. In Bavaria, eggs were laid from mid-June to the end of July on the heavily sunlit Dryas octopetala cushions in rock-strewn terrain. The eggs are laid individually. The caterpillars spin a silken web and anchor leaves together to make a shelter in which they congregate. They hibernate over winter and pupate in a similar shelter the following spring. A two-year development cycle was observed in the Rätikon (Vorarlberg) above 2000 m. The caterpillar of the first larval stage only eats for a few days and then makes a housing on the leaves of the host plant for the first hibernation, a second hibernation takes place in the pupal stage. When breeding in the lowlands, the caterpillar develops directly into the pupa, which then overwinters. There are also breeding observations, according to which the caterpillars grow at different speeds, so that some overwintered in the second caterpillar stage, another part already overwintered as a pupa. Conservation Although some