The Marbled White Spot (Hapalotis (Erastria) fasciana).
The ground colour of the fore wings of this species (Plate [21], Fig. 7) is brownish grey, more or less clouded and sometimes suffused with blackish; the white patch on the outer marginal area is, in some examples, much obscured by dark-grey markings, and in occasional specimens the only trace of white on this part of the wing is a thin edging to the second line (ab. albilinea, Haworth).
The caterpillar is pale yellowish, with a greenish, sometimes red, tinged line along the middle of the back, and a brown one on each side; a reddish line under the black spiracles; head, brownish; the raised dots of the body are dusky edged with reddish. It feeds from July to September. A reddish form of this caterpillar has been noted. Buckler, from whose description the above has been condensed, states that the food-plant is blue moor-grass, or purple melic-grass (Molinia cærulea), and this is confirmed by Bignell, who remarks that in Devonshire he easily finds the caterpillars "feeding about half way up the blades" of this grass.
The moth is out in June and July, or in forward seasons in late May. It is partial to pine and larch trunks as a resting place during the day, and is local and more or less frequent in most of the southern counties, from Kent to Cornwall, through Somerset and Gloucester (extending into Oxford), to Hereford and Worcester, on the west, and from Essex to Norfolk on the east. A specimen was taken at light in Chester in June, 1901.
The range abroad extends to Japan.
The Silver Barred (Bankia (Erastria) argentula).
In its typical form this species (Plate [21], Fig. 4) has the colour of the fore wings olive brown, but occasionally it is
tinged with reddish in some English, and more generally in Irish, specimens. The silvery oblique lines, or bands, vary in width, and sometimes there is a distinct spur from the lower outer edge of the first band.
The caterpillar is yellowish green, with a rather darker green line along the middle of the back, and a yellow one on each side of it. It feeds on grasses, such as Poa aquatica and P. Pratensis, etc., in July and early August.