Butterfly ID
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Field guide · Sweden
Blues, coppers and hairstreaks · Sweden

Brown argus

Aricia agestis

Brown argus is one of our smaller blue butterflies, and Sweden is primarily a Skåne species, although it has become established in western Blekinge since the 2000s. It has two generations per year.

Status in this countryLeast concern in SwedenLC (Least concern)
Brown argus

Flight period

Flying with two generations: from the last week of May to the end of June, and again from August to the beginning of September.

Habitat

Blomrika, open dry meadows on sandy or sandy soils, preferably in south-facing slopes with wind protection. The distribution indicated in Sweden primarily corresponds with more calcareous sandy soils.

Identifying features

Wingspan 24–28 mm. The males are similar, with orange-red edged spots that are larger and more evenly distributed over both pairs of wings compared to our other blue-winged species with brown males. The undersides have distinctive markings with coarsely black-centred white spots in pearl bands along the outer edge and more or less continuous orange-red spots.

Similar species

No similar species are described in the sources consulted.

Distribution

Within Sweden, limited to Skåne – primarily Österlen and Vombsänkan, with more sporadic occurrences along the west coast to Bjärehalvön – and in western Blekinge during the 2000s. Significantly more widespread in Denmark. The global distribution extends from the Mediterranean and southern England to central Siberia and Altaj.

Biology

The larvae feed on various ant species, including the black ant and the red ant, and have a close relationship with ants, which tend them against sugary secretions. The first generation of larvae develop slowly and overwinter, while the second generation of larvae develop more rapidly in July. The butterflies can be numerous within small areas of flower-rich, open meadows.