Lycaena helle (Denis & Schiffermüller, 1775)

Host plants:
The larvae feed on Polygonum bistorta (= Persicaria bistorta = Bistorta officinalis), in Scandinavia also on Polygonum viviparum

Habitat:
Lycaena helle inhabits wetlands such as fens, edges of ditches and intermediate stages to bogs with the occurrence of larval host plant. The sites can be quite open, but also loosely wooded. Though new fallow patches are preferred the oviposition often occurs at spots with less dense vegetation.

Life cycle:
The pupa hibernates near the ground. The small butterflies, especially the males, fly between early May and early July (peak mid-May to mid-June) lively around the habitat and pursue other butterflies. The females are usually much more inconspicuous. Flower visiting occurs very often on the larval host plant, but also on other plants like Caltha palustris, Cardamine sp., Valeriana dioica or Primula farinosa. Oviposition takes place on the lower leaf surface. The caterpillar lives from late May until August with peak between June and mid-July, in Scandinavia and cool years even later. The larvae stay on the lower side of the leaf and cause characteristic feeding scars.

Endangerment: threatened with extinction

Endangerment factors:
Lycaena helle is threatened with extinction due to habitat destruction (intensification, afforestation, eutrophication, drinking water extraction, drainage, overbuilding).

Remarks:
Lycaena helle occurs especially from northern Europe (Scandinavia) and Poland to the east across northern Asia (to the Amur region). Further south, it is very local in central Europe and the Pyrenees.