In some publications it is referred to as two distinct species: P. alcon on wet heathland, moist fen meadows and bogs at low altitude and P. rebeli on dry and subalpine calcareous grasslands. However, genetic research has shown that both have to be considered as being one species.

This species is listed as Least Concern, since it has not declined by more than 25% in the last ten years, its Mediterranean extent of occurrence (EOO) is larger than 20,000 km² and its population size is probably larger than 10,000 adult individuals.

The Alcon Blue always occurs in local, isolated populations. In Central Europe, this species is found from the south of Sweden down to the north of Spain and from France eastwards. It is furthermore present in east Turkey and east through Siberia to Mongolia and Altai. It occurs from 0-1,000 m asl. The global distribution area of the species is situated mainly outside the Mediterranean region.

A local species, restricted to (semi-) natural areas. A decline in distribution of 30-50% is reported from Slovenia (Verovnik pers. comm. 2012). A decline in distribution of 10-30% is reported from Greece (Pamperis pers. comm. 2012). A decline in distribution (magnitude unknown) is reported from Spain (Munguira, Romo and García-Barros pers. comm. 2012). A decline in population size of 10-30% is reported from Montenegro (Franeta pers. comm. 2012), Slovenia (Verovnik pers. comm. 2012) and Spain (Munguira, Romo and García-Barros pers. comm. 2012). Distribution reported as fragmented in the Mediterranean region of Montenegro (Franeta pers. comm. 2012) and Portugal (Garcia Pereira and Maravalhas pers. comm. 2012).

The Alcon Blue occurs in local, scattered populations, on low-lying wet heathland, on moist fen meadows and bogs and on dry calcareous grasslands. In some publications it is referred to as two distinct species: P. alcon on wet heathland, moist fen meadows and bogs at low altitude and P. rebeli on dry and subalpine calcareous grasslands. However, genetic research has shown that both have to be considered as being one species. The bright, white eggs are easy to find. They are laid on the flowers and sepals of Marsh Gentian (Gentiana pneumonanthe) or Willow Gentian (G. asclepiadea) in the case of the wet P. alcon form, and on Cross Gentian (G. cruciata) by the dry P. rebeli form. At first, the small caterpillars feed on the ovaries of the foodplant, but they pass the later instars in the nests of various Myrmica ants. They hibernate and pupate in the ant nests. The Alcon Blue has one generation a year.

Changes in agricultural management (improvements like land drainage as well as abandonment) threaten this species in grassland habitats. Fragmentation and isolation is the most important threat on heathlands, although the species can survive for a long time in small habitat patches.

This species occurs in a number of protected areas across its range. In countries where the species is declining, suitable habitats should be protected and appropriately managed. The effects of conservation actions should be monitored by a Butterfly Monitoring Scheme. Egg-counts have proven to be very effective and are possible with a small time-investment.