Polyommatus pylaon (Fischer v. Waldheim, 1832)

Host plants:
The caterpillar lives on Astragalus species, mostly Astragalus exscapus.

Habitat:
Polyommatus pylaon colonizes dry meadows and embankments in pine forests and rocky slopes at altitudes up to 2000m asl. I found many larvae in the Upper Valais at 1400m above sea level on the first of May 2007, together with a first fresh male. The host plant was almost completely eaten by the caterpillars. Butterflies were common there in early June. At this time, the larvae of Polyommatus damon, a frequent companion here, were just mature.

Life cycle:
The half-grown caterpillar overwinters. Butterflies are found from mid-May (rarely even earlier) to July/early August.
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Endangerment factors:
Polyommatus pylaon is regionally heavily endangered due to habitat loss. Construction of holiday homes, roads, increasing intensification of sheep grazing and mowing, but also bush encroachment and afforestations jeopardize the last recent Central European populations.

Remarks:
In Central Europe Polyommatus pylaon is in the subspecies trappi limited to the Valais, Val d'Aosta and South Tyrol (Vinschgau). Polyommatus pylaon is otherwise distributed in Spain and south-Eastern Europe.