The caterpillar, which feeds on various marsh grasses, Carex, Luzula, etc., hatches from the egg in late summer, hibernates when about half-grown, and feeds up in the spring. It is pale greyish brown with fine yellowish freckles; there are three lines along the back; the central one dark, finely edged on each side with pale greyish, the outer ones pale; the usual dots are dusky and the spiracles are black.
The moth may be found in June and July in fens and marshes, where it hides among the herbage in the daytime, but is easily seen and netted when it takes wing at dusk, or sits on the sedges, etc., before or after flight.
It is most frequent in the fens of Cambridge and Norfolk, (Stalham), but occurs also in Suffolk; Essex (Shoeburyness); Kent (Deal); Surrey (recorded from marshes near Redhill, Dorking and Guildford); Sussex; Hants (bogs near Lyndhurst), and, according to Barrett, Somerset.
The Clay Fan-foot (Herminia derivalis).
This local species has the wings pretty much of the same shape as those of S. emortualis, and has been mistaken for that species; but the colour is ochreous-brown, and the cross lines
are dark brown. Its favourite haunts appear to be woods in Kent and Sussex, and in the last-named county it is perhaps most frequently met with in Abbots wood, Guestling, and Lewes. It has also been recorded from Essex (Colchester). (Plate [35], Fig. 6.)
The caterpillar feeds on dead oak leaves, chiefly those that have fallen to the ground. After hibernation it becomes full grown about June, and is then brown with a downy appearance; there are three faintly darker lines along the back, and the usual dots are dusky. (Plate [34], Fig. 3; after Hofmann.) The moth is out in June and July, and in the daytime may be put up from its lurking place among herbage in wood clearings, or netted as it flies in the gloaming. It is also attracted by sugar and light.
The species has been erroneously recorded from Chester and Barmouth (North Wales); and Mr. Carr informs me that he is not quite sure that a specimen he recorded from Dawlish, South Devon, was correctly identified. In the catalogue of Malvern Lepidoptera H. derivalis is stated to be rather common in that district, but the occurrence of the species in the Midlands requires confirmation.
Abroad, the range extends to Amurland.