| Family | Lycaenidae |
|---|---|
| Subfamily | Polyommatinae |
| Genus | Plebejus |
| Species | idas |
| Authority | (Linnaeus, [1760]) |
| English Name | Idas 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 Idas Blue can be found on poor grassland and heath rich in herbaceous plants, both in open places and woodland. Eggs are laid on many different species of leguminous plants, such as Broom (Cytisus scoparius), Hairy Greenweed (Genista pilosa), Common Birdsfoot-trefoil (Coronilla varia), White Melilot (Melilotus alba), and the Ericaceae, Ling or Heather (Calluna vulgaris) and Bog Whortleberry (Vaccinium uliginosum), and the Yellow Rockrose (Helianthemum oelandicum). The female deposits the egg onto a woody part of the foodplant where the egg then hibernates. The caterpillars are attended a lot by ants, especially those of the genera Formica and Lasius. When fully grown, the caterpillar crawls into the passages of the ant nest to pupate. Depending on the geographical location the Idas Blue produces one or two generations a year.
Albania / Andorra / Austria / Belarus / Belgium / Belgium: Flanders (Regionally Extinct) / Belgium: Wallonia / Bosnia and Herzegovina / Bulgaria / Croatia / Czechia / Denmark / Estonia / Finland / France / France: Mainland / Germany / Greece / Greece: Mainland / Hungary / Italy / Italy: Mainland / Latvia / Liechtenstein / Lithuania / North Macedonia / Moldova / Montenegro / Netherlands (Regionally Extinct) / Norway / Poland / Romania / European Russia / Serbia / Serbia: Serbia / Serbia: Kosovo / Slovakia / Slovenia / Spain / Spain: Mainland / Sweden / Switzerland / Ukraine /