| Family | Lycaenidae |
|---|---|
| Subfamily | Polyommatinae |
| Genus | Polyommatus |
| Species | thersites |
| Authority | (Cantener, 1835) |
| English Name | Chapman's Blue |
| European Red List 2010 | Least Concern (LC) |
|---|---|
| EU 27 Red List 2010 | Least Concern (LC) |
| European Red List 2025 | Least Concern (LC) |
| EU 27 Red List 2025 | Least Concern (LC) |
| Habitats Directive | |
| Bern Convention | |
| CITES |
The Chapman’s Blue looks very much like the Common Blue (P. icarus). However, the two black spots in the cell on the underside of the forewing are absent. It occurs in warm, dry places, such as calcareous and poor grasslands, fields of sainfoin, and abandoned agricultural land. Eggs are laid on Sainfoin (Onobrychis viciifolia), and in Greece also on Cockscomb Sainfoin (O. caput-galli). The caterpillars feed on soft parts of the leaflets, leaving the veins. The small caterpillars go into hibernation, and in those parts of the range with hot climates, the egg or undeveloped larva possibly goes into aestivation. The caterpillars are attended by ants of the genera Lasius, Formica, Myrmica, and Tapinoma, and hide themselves in the litter layer and pupate. The Chapman’s Blue usually has two generations a year, but in the south of the range also three.
Albania / Andorra / Austria / Belgium (Regionally Extinct) / Belgium: Wallonia (Regionally Extinct) / Bosnia and Herzegovina / Bulgaria / Croatia / Czechia / France / France: Mainland / Germany / Greece / Greece: Mainland / Greece: East Aegean Islands / Hungary / Italy / Italy: Mainland / North Macedonia / Malta (Possibly Present) / Moldova / Montenegro / Poland / Portugal / Portugal: Mainland / Romania / European Russia / Serbia / Serbia: Serbia / Serbia: Kosovo / Slovakia / Slovenia / Spain / Spain: Mainland / Switzerland / European Türkiye / Ukraine /