Vacciniina optilete (Knoch, 1781)

Host plants:
The caterpillars feed on Ericaceae such as Vaccinium uliginosum, Vaccinium vitis-idaea, Andromeda polifolia, Oxycoccus palustris (= Vaccinium oxycoccus) etc.

Habitat:
In the lowlands Vacciniina optilete usually inhabits bogs, often accompanied by Colias palaeno. In the higher mountains, e.g. in the central Alps, it is found in acidophilous dwarf shrub belts (often also with Colias palaeno), where it can be a bit more numerous.

Life cycle:
Vacciniina optilete flies in a single generation mostly in June/July. The adults feed on inconspicuous flowers e.g. of Vaccinium vitis-idaea and V. oxycoccus and are thus not dependent on adjacing flower-rich fens etc. The adults are most numerous in the transition zone between bog woodland and open bog. The eggs are deposited singly on both sides of leaves (more commonly on lower side), but also twigs, fruits or moss and lichens (when ovipositing near the ground). The young larvae cause a feeding pattern similar to Colias palaeno, but more from the lower side of the leaves. Vacciniina optilete hibernates as young caterpillar (L3, sometimes L2) in the litter. In spring they climb the sprouting plants and preferably feed on flower buds and flowers if available.

Endangerment factors:
In the lowlands, Vacciniina optilete is highly threatened by destroyment and degradation of the last bogs such as eutrophication and succession after partial dewatering. In the central Alps and especially in Scandinavia, the endangerment is much less severe, even if many populations are decimated in the Alps through development measures for the exuberant tourism (skiing!).

Vacciniina optilete may be also threatened by global warming.

Remarks:
Vacciniina optilete shows an holarctic distribution (Europe, cooler parts of Asia to Japan, local in North America). In Europe, Vacciniina optilete occurs especially in the central (e.g. Alps) and northern parts (Scandinavia).