Very similar to the last species, but generally smaller, neater and more glossy looking. The central band of the fore wing is blacker, without ochreous clouding below the middle, and the edges are not wavy. The hind wings are darker, and the only distinct band is a whitish one beyond the middle (Plate [93], Figs. 3, 6).
The caterpillar is yellowish green, with a series of dull olive or rust coloured spots or bars along the back, bordered on each side by a dusky olive line; in some examples the markings are absent (Crewe). It feeds in the flowers of yellow toadflax (Linaria vulgaris), and may be reared on flowers of the snapdragon (Antirrhinum). It is hardly necessary to examine each blossom separately to find the caterpillar, except, perhaps, to make sure when doubtful about the quarry being there. Probably, a handful of the flower sprays gathered in August or September in any locality in the southern half of England where the food plant abounds would furnish moths in the following May or June. The Linaria should be secured on a dry day for choice, but when brought home it need not be put in water; just throw it into an airy breeding cage, and hopefully await emergence of the perfect insects in due course. Sometimes caterpillars attain the moth state the same year.
The range of the species in England extends to Durham, but it seems to be rather uncommon from the Midlands northwards. It is found in Wales, and has been recorded once from Scotland (Inverurie), and once from Ireland (Dublin).
Marbled Pug (Eupithecia irriguata).
The fore wings are whitish and rather shining, the discal spot is black and very distinct, but the dark grey-brown markings, which are only well defined on the front and outer marginal areas, vary in intensity (Plate [93], Fig. 9).
The long, slender and roughened caterpillar is dull yellowish green; three lines along the back, the central one reddish and expanded on the middle rings, the others yellowish; head, reddish. It feeds on oak, in late May and in June. The moth is out in April and May, and is sometimes found on fences or palings in the neighbourhood of oak woods, but may be jarred from the oak boughs, on the undersides of which it usually sits.
The New Forest in Hants is, perhaps, the best British locality for the species, but it has been found in Dorset (Glanville's Wootton), Devon (Exeter district, Tiverton, etc.), Sussex (Abbots Wood, St. Leonard's Forest, etc.), Wilts. (Savernake Forest); also oak woods in Surrey, Berks., Gloucester, Hereford and Glamorgan. On the eastern side it occurs in Suffolk (Bury and Needham), and Norfolk.
Dwarf Pug (Eupithecia pusillata).
The fore wings of this species (Plate [93], Fig. 12) are pale greyish white, discal spot black, cross lines irregular dark grey inclining to brownish, usually most distinct on the front margin.