The eggs are laid on Thymus species and Origanum vulgare where the young caterpillars live. Later, the caterpillar lives in ant nests (Myrmica sabuleti), where they also hibernate.
Maculinea arion inhabits nutrient-poor, dry and sunny grasslands with occurrence of larval host plants and the host ants.
Maculinea arion flies in a single generation from mid-June to August, mostly in July. The adults like to feed on sainfoin (Onobrychis), but also on the flowers of the larval host plant.
Endangerment: strongly endangered
In the lowlands, Maculinea arion is threatened by grazing abandonment and loss of habitat. The butterfly is still present in many grasslands of the Swabian Alb, but the abundances have declined in recent years. In the Alps (also in Bavaria), Maculinea arion is still fairly widespread.
Maculinea arion is distributed locally in Europe and temperate Asia to the Pacific. In Europe it is extinct in the UK and in Southern Europe spread only very local in the higher mountains. Maculinea arion is more common in the Alps (mainly on limestone).