When freshly laid, the egg is whitish, but changes to pale orange. The caterpillar (Plate [92], Figs. 2, 2a) is greenish, with more or less connected reddish marks on the back, or green inclining to yellowish, or bluish, without markings. It feeds through the summer on flowers of ragwort, knapweed, scabious, yarrow, golden rod, etc.
The moth, which is often common in gardens, is out from May to August, and specimens of a second brood occur in September and October.
It is widely distributed over the British Islands, but in Scotland it does not, apparently, extend north of Perthshire.
Foxglove Pug (Eupithecia pulchellata).
The fore wings are pale ochreous brown with a dusky basal patch limited by a black line; a greyish central band inclining to blackish near the costa, and clouded with ochreous below the middle; the black-and-white edges are wavy; a reddish stripe across the wing before the central band, and a similar, but more irregular, one beyond the band. The hind wings are whitish grey, with several dark-grey bands (Plate [93], Figs. 7 ♂, 10 ♀).
In var. hebudium, Sheldon, from the Hebrides, the usual reddish stripes are replaced by narrower dark-brown ones; the space left by the reduction in width is white, giving the insect a decidedly grey appearance.
The caterpillar lives in the flowers of the foxglove (Digitalis purpurea) and feeds therein upon the stamens and the immature seeds. It enters by boring through the side walls, and then secures the longer lobe of the blossom to the shorter upper one with a few silken threads. Tenanted flowers have
a rather faded look and are easily detected. July is the best month, but the caterpillar may be found earlier as well as later.
The moth is out in May and June, and is found in almost every part of the British Isles where the foxglove is common.