(Poda, 1761)
Chalkhill Blue
Description:
The Chalkhill Blue occurs on calcareous soil in dry, and flower-rich places with a short vegetation. They seem to prefer sheltered places. Sometimes, populations can be extremely large which is especially obvious in the late afternoon when the butterflies come together to roost. Hundreds of butterflies can be seen, their heads pointing downwards into the vegetation, wings upright, the light-coloured underwings gleaming in the evening sun.
Horseshoe Vetch (Hippocrepis comosa) is its only food plant, the female laying her eggs on the leaves. The eggs hibernate. The caterpillars are attended by ants of the genera Myrmica, Lasius, Formica, Plagiolepis, Tetramorium, and Tapinoma. The Chalk-hill Blue pupates in the litter layer.
It usually only has one generation a year.
Habitat:
Dry siliceous grasslands
Dry calcareous grasslands
Mesophile grasslands
Similar species:
Polyommatus caelestissima
Polyommatus philippi
Polyommatus hispana
Polyommatus albicans