Satyrium w-album (Knoch, 1782)

Satyrium w-album: Adult (Illerbeuren near Memmingen, August 2013) [N] Satyrium w-album: Male [N] Satyrium w-album: Adult [S] Satyrium w-album: Female (Olympus, Greece, July 2010) [N] Satyrium w-album: Ovum (eastern Swabian Alb) [N] Satyrium w-album: Ovum [M] Satyrium w-album: Egg (late December 2012, Schwäbisch Gmünd, Germany) [M] Satyrium w-album: L1 after hatching [S] Satyrium w-album: L1 (end of this instar) [S] Satyrium w-album: Half-grown larva [M] Satyrium w-album: Larva [M] Satyrium w-album: Larvae, right larva discoloration prior to pupation [S] Satyrium w-album: Larva [M] Satyrium w-album: Pupa [S] Satyrium w-album: Pupa [S] Satyrium w-album: Pupa [S] Satyrium w-album: Die pupa is attached in the field at least sometimes between leaves (Swabian Alb, Southern Germany, May 2008), but probably also at trunks oder near the ground. [N]

Host plants:
The larva feeds on Ulmus species, very often Ulmus glabra.

The habitat is diverse and determined by the larval host plant. It ranges from individual trees in the landscape over bushy grasslands on the Swabian Alb with Ulmus glabra to woodland edges, ravine forests and other woodlands.

Life cycle:
The egg or better the caterpillar overwinters in the egg membrane. The caterpillar is mature in mid or late May and the butterflies fly from mid-June to mid-July.

Endangerment: endangered

Endangerment factors:
Satyrium w-album was originally one of the most common and widespread hairstreak species. But it has extremely declined due to the elm disease. In areas where the elms are still represented better, it is still quite common because just a few trees or even a single tree suffice for reasonably stable, small populations. In addition, Satyrium w-album is threatened by spruce monocultures.

Butterfly observations are rare, for example on nectar plants like Sambucus ebulus. Satyrium w-album can easily be detected by searching for the eggs in winter, as it is the case with Satyrium spini, S. ilicis or Quercusia quercus. Eggs of Satyrium w-album can be found by scanning the top of the lowest branches of trees with flower buds. Most eggs are observed at the base of terminal leaf buds (hardly of flower buds). Alternatively, the fully-grown caterpillars are quite conspicuous on the leaf undersides of the lowest branches in mid- or late May.

The overall distribution ranges from Northern Spain across much of Europe and the belt of the deciduous forests in temperate Asia to Japan.

Satyrium acaciae | Satyrium esculi | Satyrium ilicis | Satyrium ledereri | Satyrium pruni | Satyrium spini