Lepidoptera The Red Underwing Moth – Catocala Nupta
The other three members of the family are very similar in appearance, the fore wings of all being marbled with shades of grey, relieved by touches of black and brown; and the hind wings, red or crimson, give the popular names to the species.
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.