The moth is out in May and June, sometimes later; examples of a second brood have been obtained in August and September. It flies in the afternoon, but only when the sun shines, and where the food plant grows freely.
The species occurs in all the eastern counties of England, in Bucks., and in the northern counties to Cumberland and Northumberland. In Wales it has been recorded from Colwyn, Denbighshire; in Scotland it is widely spread to Perthshire; it is local and scarce in Ireland.
Slender Pug (Eupithecia tenuiata).
The fore wings are rather rounded; grey, more or less tinged with brownish, and with ochreous or reddish brown along the front edge; the latter with dusky clouds upon it; the cross lines are dark grey brown and fairly distinct, and the discal spot is black (Plate [98], Fig. 5). A large grey form from Moray, in Scotland, has been named cineræ, Gregson.
Caterpillar, rather stumpy, and dingy yellowish green in colour, the sides and middle of the back rosy; a series of dusky spots, edged by black lines or short streaks, along the back; and a row of pinkish oblique stripes on the sides. It feeds, in the spring, in sallow catkins, and the moths may often be bred in numbers, in June and July, from those catkins which fall most readily from the bushes when we go "a sallowing." Moths frequently rest on the stems, and where there is a clump of well-grown sallows, a good series may be obtained.
The species is partial to fens and marshy places, and is found in such situations over the greater part of the British Isles.
Maple Pug (Eupithecia inturbata).
The fore wings are greyish brown, with many darker cross lines; the outer margin is darker and traversed by a pale line; discal dot, dark grey and not very distinct (Plate [98], Fig. 6). This species was long known as subciliata, Guenée, but is now referred to inturbata, Hübner.
In May and June the caterpillars may be beaten from maple, which is apparently the only food plant, and of which they have a decided preference for the flowers. When full grown the larva is yellowish green with a purplish stripe along the back, and whitish lines along the sides.