Pyrgus centaureae (Rambur, 1839)

Host plants:
The larvae feed on Rosaceae and Betulaceae. In Scandinavia and North America Rubus chamaemorus is known as a host plant. Fragaria and Potentilla (both also Rosaceae) are as well known in North America. In N-Sweden, I observed ovipositions not only on Rubus, but even more numerously on Betula nana (June/July 2020). This may be a surprice, but dwarf birch is much more common in tundra and bog vegetation than Rubus. The larvae accepted Betula readily.

Habitat:
Pyrgus centaureae inhabits open and semi-open bogs and tundra. In northern Scandinavia it is found up to approximately 1000m, in N-America much higher (Rocky Mountains). In the Appalachians it settles also in woodland clearings, power-cuts and similar places.

Life cycle:
The pupa hibernates and the adults appear already early after snowmelt. In Scandinavia, the flight period is usually between late May and mid-July. In N-America in lower altitudes in more southerly regions, adults appear as early as March and fly until May. The males perch often in the edges of bogs in the transition zone to somewhat higher vegetation with dwarf willows or birch and follow other insects. The adults visit also unimposing flowers such as Vaccinium or Andromeda because of the general sparseness of flowers in their habitats. In most regions the lavae hibernate quite small in the second or third instar. Only in lower altitudes of more southerly sites (probably only in eastern North America) the larvae pupate in the year of oviposition so that there can be a one-year-cycle.

Remarks:
Pyrgus centaureae occurs around the Arctic in northern Europe, northern Asia and northern America. Especially in north-south trending mountain ranges, it may occur south of its main distribution, e.g. in the Rocky Mountains up to New Mexico or at isolated locations in the Appalachians (ssp. wyandot). The same applies to the Scandinavian mountain range where Pyrgus centaureae has been recorded southward to south of Hardangervidda national park in Norway. In Sweden, it is found also in boggy regions outside the mountains, southward to the regions north of the large lakes (e.g. Västmanland).

Literature:
Wagner & Markl (in press): Pyrgus centaureae (RAMBUR, 1839) – a contribution to its larval ecology in Sweden (Lepidoptera: Hesperiidae).- Nachrichten des entomologischen Vereins Apollo