Blue Butterfly Refuge - Zakrzówek
Hidden Corners
Meadows protected as the Zakrzówek ecological site, where scarce large blues fly in July and August. Their caterpillars grow up in ant nests, so the butterfly can survive only together with the meadow, the great burnet and the ants.
The scarce large blue
The scarce large blue (Phengaris teleius) is a small butterfly with a wingspan of about 3 cm. The male has light blue wings with a broad dark border and a row of black spots, while the female is darker, brown with a bluish sheen. Adult butterflies fly from early July to the end of August and live for only a few days.
The female lays her eggs on the flower heads of great burnet, a plant of damp meadows with dark red, elongated heads. For two or three weeks the young caterpillar eats the flowers, then drops to the ground and waits for ants. Worker red ants, most often Myrmica scabrinodis, mistake it for one of their own larvae and carry it into the nest. There the caterpillar eats the hosts' larvae, spends the winter and pupates in June. It leaves the ant nest as a butterfly.
So the large blue can survive only where three things come together: great burnet, the right ants and a meadow mown rarely and at the right time. Such meadows are threatened by shrubs taking over, drainage, fertilisation, mowing too often in summer and building development. In Poland the species is strictly protected, and throughout the European Union it is protected by the Habitats Directive.
The refuge at Zakrzówek
The area between Wyłom Street and św. Jacka Street is a mosaic of trees, shrubs, fresh meadows and warmth-loving grasslands right next to the former quarry. In 2018 Kraków City Council created the "Zakrzówek" ecological site here. Besides the scarce large blue and its relative, the dusky large blue, it is home to the fire-bellied toad, the great crested newt, the sand lizard and the smooth snake.
In 2023 naturalists from the Jagiellonian University, the Polish Academy of Sciences and the NATRIX Herpetological Society asked for the protection to be extended. They pointed to a damp purple moor-grass meadow with Siberian iris and broad-leaved marsh orchid, as well as sites of the large blues, whose numbers have been estimated here since 2008. On 28 August 2024 the councillors added the "Zakrzówek - eastern enclave" ecological site, covering about one and a half hectares, to the refuge. The Voivode annulled this resolution, but in January 2025 the administrative court overturned his decision and the protection is in force.
Within the ecological site it is forbidden to damage or alter the land, carry out earthworks, change the water conditions, pick plants or kill wild animals.
Did you know?
The scarce large blue disappeared from the Netherlands in 1976. It only returned in 1990, when naturalists brought in butterflies from other populations. Kraków's refuges are therefore something many European countries no longer have.
How to look
Keep to the trodden paths and do not pick the great burnet, as it is the only plant on which the females lay their eggs. The butterflies are easiest to see on a sunny day in July and August, when they settle on the dark red flower heads.