Thumatha senex, the round-winged muslin, is a moth of the Arctiidae family. It is found in northern and central Europe, the Alps, northern Asia Minor, the Crimea and south-western Siberia.

Technical description and variation

See glossary for terms used
The wingspan is 15–20 mm. Not unlike Nudaria mundana ( mundana has less-rounded forewings and a more transparent appearance, less obvious spots). The central spot at the apex of the cell distinct; a larger shadowy spot at the middle of the costa, and before the marginal area of the forewing a row of spots which are especially distinct in the costal region. Another curved row of spots bounds the basal third of the forewing. The wings are sparsely scaled, giving them a thin, papery appearance.


Habitat.Ireland.
Biology

Adults are on wing from mid June to mid August in one generation.

Egg round, yellow. Larva ashy grey, very hairy, with black head. The larvae feed on lichen (especially Peltigera canina) and mosses.Pupa stumpy, dark brown, in a dense hairy cocoon.

The moths fly on damp meadows, and are not rare in their flight-places; they come to the light at night.


source - Wikipedia