The Red Underwing flies in August and September, and is common in the southern counties of England, as well as in some of the midland counties; it may be often seen flying by day around willows.
The caterpillar is similar in form to that of Fraxini, and when at rest by day on the bark of its tree it is very difficult to detect, so closely does it apply itself to the surface, and so perfectly does it imitate the colour of its surroundings. It feeds on the crack willow (Salix fragilis), sallow (S. alba), poplar (Populus), and plum (Prunus), and is full grown in June.
The Dark Crimson Underwing (Catocala Sponsa)
This beautiful insect is represented on [Plate XI] (fig. 6). It will be observed that the black band crossing the centre of the hind wing is rather broad and sharply bent—an important feature, since it is the most serviceable distinguishing mark between this species and the Light Crimson Underwing (C. Promissa).
The caterpillar is similar in form and habits to those of Fraxini and Nupta, and feeds on the oak. It is full fed about the beginning of June, when it changes to a chrysalis between leaves which it has spun together with silk.
The moth flies in July and August, and is common only in certain oak woods of the southern counties. It is particularly abundant in the New Forest, where scores may be taken in a single night by judicious sugaring.
There yet remain a few small families of the Noctuæ, but we must leave them in order that we may give a proportionate share of our space to the other great division of the larger moths—the Geometræ.