Thumatha senex (Hübner, [1808])

Host plants:
The larvae feed on algae, mosses and especially dead parts of higher plants like Carex. Where avaialble also lichens may be eaten, but usually lichens miss in the larval habitat.

Habitat:
Thumatha senex inhabits wetlands like riparian woodlands, swamps, lake and river shores, fens and wet, unmown meadows and reeds. In S-Germany (river Iller) I recorded the larvae most numerously in water-logged, unmown Carex elata marshes directly along the river. These marshs were interspersed with more and less dense stands of Phragmites. The larvae inhabit the wet detritus layer and feed on the slowly decaying old sedge leaves etc. During humid weather or early in the morning they are sometimes higher in the detritus layer, but withdraw near the ground in dry conditions. Best detection method for larvae is shaking detritus above a reversed umbrella.

Life cycle:
The young larvae hibernate and are mature between mid-May and June. Pupation occurs in a cocoon in which larval hair is incorporated. The moths usually fly between mid-June and mid-August. They often swarm numerously in their quite confined habitats already at dusk.

Remarks:
Thumatha senex occurs in central and northern Europe including the British Isles.