The young caterpillars live in flower heads of Sanguisorba officinalis, the older caterpillars in ant nests (Myrmica sp.).
PrimarilyMaculinea teleius inhabits Sanguisorba-rich wetlands (fens, Molinia meadows). In addition, sometimes small populations sometimes occur in light, damp coppice forests at grassy places. Especially formerly also wet, extensively maintained agricultural meadows were populated.
The adults fly from late June to early August. The eggs are deposited on not yet blossomed, often secondary flower buds. The young caterpillars are then - after they reach the ground - adopted by ants of the genus Myrmica (mostly M. scabrinodis), where they are maintained by the ants and also devour their brood. Pupation also takes place in the ant nest.
Endangerment: threatened with extinction
Maculinea teleius is highly endangered because its habitats are shrunk in recent decades by an estimated 95% (agricultural intensification, drainage, afforestation) and still decrease (eutrophication, abandonment of extensive mowing, overbuilding by always new roads. Maculinea teleius needs an autumn cutting (best in early October) with removal of the crop, as it can not survive in pure fallow land for longer periods (unlike Maculinea nausithous).
The distribution in Europe is largely limited to a narrow strip from eastern France (also isolated in the Atlantic in the west) across Germany, parts of Austria and Switzerland to the east (south of Poland, the Czech Republic, etc.). In addition, the overall distribution ranges across some parts of temperate Asia to Mongolia and Japan.