Abroad, it extends to East Siberia, Amurland, and Japan.
The Plain Golden Y (Plusia iota).
In typical specimens the metallic mark is V-shaped, with a dot below and a little to one side (Plate [24], Fig. 8). In ab. percontationis, Treit. (Fig. 7), these spots are united and form a Y-like mark. Sometimes the spot is absent and the V-mark much reduced, and more rarely the V also disappears (ab. inscripta, Esp.).
The larva is yellowish green, white dotted, with a white-edged darker line along the middle of the back; a band composed of whitish irregular lines runs along the sides, and a thin yellow line along the area of the spiracles. It hatches from the egg in the late summer, hibernates when quite small, and feeds up in the spring. The food plants comprise the dead nettles (Lamium), woundwort (Stachys), mint, stinging nettle, honeysuckle, hawthorn, etc. There is a record of sixteen larvæ which hibernated among dead leaves of Lamium album, resumed feeding on February 18, spun up April 23-25, and produced moths May 27-June 4. Usually the moth is on the wing in June and July.
The species seems to be pretty widely distributed throughout the British Isles to the Orkneys; it was not known to occur in the Hebrides until 1901, when McArthur obtained it in the Isle of Lewis.
The Beautiful Golden Y (Plusia pulchrina).
This species (Plate [24], Figs. 5 and 6) so closely resembles the last that it has been considered a variety thereof; there is no question, however, that it is quite distinct. The fore wings in both species are somewhat similar in general tints, but the following points of difference distinguish pulchrina—the darker colour is less evenly displayed, and gives the wings a more mottled or marbled appearance; the cross lines, especially those on the basal area, are almost invariably golden edged; the second cross line is more acutely bent inwards above the inner margin, the reniform has a more or less complete golden outline, and it is placed in a dark cloud; the golden V-mark and dot below are generally thicker. As a rule, the fringes of all the wings are more distinctly chequered, but this feature cannot be relied on alone in separating one species from the other. In ab. percontatrix, Aurivillius (= juncta, Tutt), the golden V and dot are united and so form a Y-mark (Fig. 5).
The caterpillar is green with a broad central white stripe and several finer white lines along the back; a yellowish-tinted white stripe low down along the sides; head shining, marked with black on each side of the mouth. This caterpillar has the bristles rather more in evidence than they are in the larva of P. iota. It feeds on various low-growing plants, such as the dead nettles, groundsel, etc., also on honeysuckle and bilberry.
The moth occurs in June and July, and is found more or less frequently all over the British Isles to Orkney, but in England is more plentiful from the Midlands northwards than in the southern counties.