The Icilius Blue or Amethyst Hairstreak (Jalmenus icilius) is a butterfly of the Lycaenidae family. It is found in all mainland states of Australia, throughout much of the subtropical areas of the inland, from the Selwyn Range and from Carnarvon to Kalgoorlie. It is generally common except in the south-eastern end of its range in central and western Victoria, where it is now very scarce. The wingspan is about 30 mm. The Caterpillars are attended by the ant species Iridomyrmex rufoniger.