The sexes of this black-clouded grey moth are shown on Plate [100], Figs. 8 and 9♀. Except that the black clouding sometimes spreads over a greater area of the fore wings, there is little to note in aberration, at least in a general way. In 1906 a melanic specimen was bred from a chrysalis taken from alder in Delamere Forest, Cheshire; this is probably referable to var. steinerti, Caspari.
The caterpillar (Fig. 26) is black, marked with yellow; the
curious clubbed hairs are its distinguishing feature. Although named after the alder, it feeds on the leaves of most trees and bushes in July and August, sometimes earlier or later. The moth is out in May and June, but although an occasional specimen has been taken at sugar or light, once resting on nettles, it is rarely met with. Caterpillars also are not by any means common, and any one who may obtain even a single example in a season may congratulate himself on a good find. They are perhaps most frequent in the Hampshire (New Forest) district and some of the Sussex woodlands, but have occurred now and then in almost every county of England up to Yorkshire; also in Glamorganshire, Carmarthenshire, and at Trefriw in Wales. The only Irish locality is Powerscourt, Co. Wicklow. The range abroad extends to Armenia, Amurland, and Japan.
The Marsh Dagger (Acronycta strigosa).
This little moth, known also as the "Grisette," seems confined, as a British species, to the country around Cambridge; but it has been twice recorded from Norfolk, two specimens have been reported from Worcestershire, and one from Gloucestershire; the latter at sugar in June, 1897. The latest records that I have seen refer to a moth taken at sugar near Chatteris
in 1904, two caterpillars beaten out of hawthorn in August, 1905, and a moth on an ash tree, Wicken, July 31, 1907. (Plate [100], Fig. 7).
The caterpillar is yellowish green, with a red brown stripe along the back; two small elevations on ring four, and one on ring eleven; the hairs are blackish on the back, one of each tuft longer than the others. It feeds on hawthorn in August and early September. The moth is out in July. This species is found abroad in Central Europe and Southern France; also in Amurland, Corea, and Japan.
The Dark Dagger (Acronycta tridens).
The English name of this moth is not very suitable, as in general colour it is often really paler than many examples of the next species. Specimens with a blackish cloud at the base, and a dark band-like suffusion on the outer margin of the fore wings are referable to var. virga, Tutt. It is widely distributed in England and Wales, but apparently not common; rare in Scotland and in Ireland. I am unable to indicate any character that will serve to distinguish this moth from the Grey Dagger. The moth flies in June; a second brood sometimes occurs in confinement in October. The caterpillars of the two species are very distinct. That of the present species is black, with a broad reddish stripe along the back, and one on each side; the first is interrupted with white, and the others with black; there is a black hump on the fourth ring, and a broader one on the eleventh ring. It feeds from August to October on hawthorn, sloe, plum, pear, and apple; also on birch and sallow.
The moth is shown on Plate [100], Fig. 10; and the caterpillar on Plate [101], Fig. 4.