In its typical form this species (Plate 21, Fig. 4) has the colour of the fore wings olive brown, but occasionally it is {58} 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. The moth is out in June, and may be found during the day sitting about on the herbage in its marshy haunts, or flying over the vegetation towards the evening. The species is exceedingly local in Britain. In ancient times it occurred in Norfolk, but in the present day it seems to be confined to Cambridgeshire, in which county it was first noted rarely in Wicken fen about thirty years ago, but in 1882 it was found plentifully in Chippenham fen, and in that locality (which is a private one) the species still flourishes. In Ireland it is well distributed over co. Kerry, and is especially abundant on the bogs of Killarney. The range abroad extends to Amurland, where the brownish form var. _amurula_, Staud., is found. THE SILVER HOOK (_Hydrelia_ (_Erastria_) _uncula_). The usually olive brown central area of the fore wings is sometimes reddish tinged, and in fresh specimens the whitish front marginal streak is distinctly rosy; the reniform stigma, which appears to be a spur of the costal streak, is also white or rosy tinged, and sometimes encloses a greyish mark. This stigma is the so-called "hook" to which both the English name and the Latin specific name refer. (Plate 21, Fig. 5.) The caterpillar feeds in July and early August on sedges (_Carex_) and coarse grasses. It is green, with three lines along the back, the central one rather darker green, and the other two whitish; low down along the sides is a broader yellowish line; the head is green with a yellowish tinge. [Illustration] 2 Pl. 22. 1. THE HERALD. 2. THE DARK SPECTACLE. 3. THE SPECTACLE. 4. GOLDEN PLUSIA. 5, 6. BURNISHED BRASS. [Illustration] 2 Pl. 23. 1. CHAMOMILE SHARK: _caterpillar_. 2. THE FOUR-SPOTTED: _eggs_. 3. STRAW DOT: _caterpillar_. {59} The moth is out from late May to early July, sometimes later.