Host plants:
The caterpillars feed on Salix species with rough leaves. I found caterpillars on Salix caprea, S. appendiculata, S. cinerea and S. aurita (a single observation also on S. pentandra).
Habitat:
Nycteola degenerana inhabits mesophilic to most often humid inner woodland edges with softwood species in semi-shaded to shady areas (clearcut edges, roadsides, borders of streams and lakes).
Life cycle:
Nycteola degenerana flies in a single (as mostly in the Allgaeu/Alps) or two generations per year (e.g. in hot summers like 2003 or in lower elevations). The moths overwinter. Caterpillars can be found from late May to mid-July and in the case of a partial second generation again be from July to August. The larvae usually live in small groups of 2-5 individuals on a branch with several fresh shoots, which tips they cover with a loose weave.
Endangerment: endangered
Endangerment factors:
Nycteola degenerana has no high requirements. Nevertheless, it is at times driven back by cutting economically worthless softwood by forestry.
Remarks:
Overall, Nycteola degenerana is distributed locally from France across central and northern parts of Europe and across temperate Asia to Japan. In Central Europe the occurrence is focused mainly on the mountains. A center of distribution is currently the northern and central region of the Alps and the adjacent foothills, where it was detected around by the author in many places in the woods (as in the whole Allgäu) since 2000. But it seems to retract its distribution again in the last years at least in the northern foreland of the Alps.