Description: Wingspan 18-27mm. This is the smallest N. Irish butterfly and is distinctive for this reason alone. The sexes are similar. The upperside is dark smoky grey with white fringing hairs. The underside is silvery grey with numerous small black dots. Sexes differ little in size. Males show a blue suffusion at base of wings on both sides. Single brooded. In Fermanagh it has been recorded between the end of May and mid July.

World Distribution: Central and southern Europe except most of Iberia; absent from most of northern Europe; eastwards through Eurasia as far as Mongolia.

Irish Distribution: This is the rarest N. Irish butterfly now confined to just one colony in the Monawilkin area of west Fermanagh. Other populations existed on Islandmagee and the north shore of Belfast Lough in south Antrim but these died out in the late 19th Century. A second Fermanagh colony was lost in the 1970s.

Ecology: A colonial species found in calcareous and dune grassland. In N. Ireland the only colony is found on lightly grazed, short limestone grassland. Adults fly low over the habitat. Males gather in tall vegetation waiting for females. Once mated females avoid males and remain close to feeding and egg-laying sites. Females lay on the flowerheads of Kidney Vetch Anthyllis vulneraria. The larvae feed internally on the flower and developing seedhead except when nearly fully-grown. The full-grown larva overwinters.

Key Identification Features:

• Unmistakable due to tiny size and sombre colour.

Distribution Map from NBN: Cupido minimus at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Cupido minimus at iNaturalist World Species Observations database.