This family contains only four British species, but these few are very striking moths. They are of large size; and, unlike the Noctuæ generally, the chief adornment is reserved for the under wings. When at rest, the outer or fore wings completely hide the other pair, and then their general appearance is dull, though if closely examined it will be observed that these outer wings are really beautifully marbled with shades of grey.
The caterpillars of this family are very peculiar creatures. Their bodies are convex above and flattened beneath; and if disturbed as they rest on the bark of a tree, instead of leaving their hold and rolling into a ring like so many other larvæ of Noctuæ, they apply themselves the closer, and hold on as if to defy our attempts to remove them. Another peculiarity of these larvæ is the possession of fleshy projections along the sides, just above the legs. They feed on the leaves of trees, and when about to rest they descend to the trunk, and there remain protected by their imitative colouring, detection being rendered even more difficult by the close application of their flattened under surface to the bark. Before changing to the chrysalis state, they spin a light cocoon among the leaves or on the bark.
The Clifden Nonpareil (Catocala Fraxini)
This is the largest of the family, and, indeed, of all British Noctuæ. The fore wings and thorax are light grey, dotted and marbled with darker grey (see fig. 5, [Plate XI]); and the thorax and abdomen are banded with black and greyish blue.
The young entomologist can hardly expect to meet with this fine insect, for it is very rare, and it is only occasionally that a specimen is seen in Britain; but its characteristics are so striking that we have endeavoured to find it a place here. Reputed British specimens of Fraxini command the price of a few pounds each, but specimens from the other side of the Channel may be obtained for a few pence. With such rarities we should advise a young entomologist to purchase
the foreign specimen rather than adopt the two other alternatives—give an exorbitant price for a supposed Britisher, or else remain a stranger to the gem, but all foreign specimens should be labelled according to their nationalities.
The Red Underwing (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.