The larvae feed on Anthyllis vulneraria and also other species of Anthyllis in Southern Europe.
Polyommatus dorylas inhabits nutrient-poor grasslands, embankments, rocky slopes and similar places. Important are spots with open ground which ensure a warmer microclimate. In Valais, I know Polyommatus dorylas fro a steppe slope in light larch forest at 1800m above sea level, where also Maniola lycaon flies. I found caterpillars in the Valais, in the Swiss Jura and in the eastern Pyrenees on or under strong Anthyllis plants that were growing on rock, sand or otherwise gappy grown soil under warm microclimate conditions.
Polyommatus dorylas flies in June and July, rarely also sooner (observations in May in Northern Greece) or later (observations in August on Mount Olympus in 2500m NN), usually in a single generation. The caterpillar overwinters. In mid-May, I found about 5 mm long larvae at over 1500 meters above sea level in the western Swiss Jura and mature ones in early June in nearly 2000m above sea level in the Valais.
Endangerment: threatened with extinction
Polyommatus dorylas is threatened by succession after abandonment, eutrophication, intensification and locally also overgrazing. Polyommatus dorylas obviously needs gappy places with open ground, rocks or stones as well as low growing areas with warm microclimate.
Polyommatus dorylas occurs from Northern Spain across parts of Europe (as far north as southern Sweden) to Western Asia.