Host plants:
The larvae feed within the seed capsules of Silene dioica.
Habitat:
Perizoma affinitata inhabits mostly humid forests, where the larvae are often not rare in Silene stands along streams, ditches and forest roads.
Life cycle:
The pupa hibernates and the adults are on the wing in one or more rarely also two generations between late April and August. I observed the larvae near Schwäbisch Gmünd (S-Germany) between June and August. They seem to change the capsule occasionally. If the capsules are ripe and the plant often dies, the larvae web the opening of the capsule and thus the seeds stay within it.
Remarks:
Perizoma affinitata is quite widespread in Europe, but misses in some regions like the S-Balkans (especially Greece).