The larvae feed on Hippocrepis (especially Hippocrepis comosa) and rarer also Coronilla varia.
Polyommatus coridon colonizes all kinds calcareous grasslands from the lowlands up to about 2100m.
Polyommatus coridon flies in one generation from late June or more often early July to October. Eggs are laid close to the ground on stems and leaves of Hippocrepis, but often also on moss, lichens and other plants (leaf underside of Helianthemum and Potentilla) near Hippocrepis pads. The caterpillar overwinters in the egg. The nocturnal caterpillar is often found in the dozen under Hippocrepis-pads and can cause defoliation in the end of May and in June.
Polyommatus coridon is in decline due to habitat loss. But on the other hand it is still obviously only little threatened. Limestone-grasslands have declined significantly and are still in further decline, but Polyommatus coridon is able to reproduce in even small ones. For example, it lives almost in all the limestone juniper grasslands of the Swabian Alb, and is also common in the Alps. But in regions with traditional low alkaline grassland stocks, the isolated populations often collapse like they did in the southern German Iller valley due to dense afforestations and further affections of the former floodplains.
Polyommatus coridon is distributed from Northern Spain and southern England across large parts of Europe (excluding Scandinavia) to the Urals.