The moth appears in March and April, and, in the daytime, is often met with at rest on posts, fences, and the trunks of trees; also upon stone walls, but seemingly less frequently, probably owing to the moth being then less easy to detect. At night it flies around sallow bushes and sometimes settles on the catkins, but is always on the alert.
The Sword-grass (Calocampa exoleta).
Except that the pale grey brown fore wings are more clouded with blackish in some specimens than in others, there is little of importance to note. Usually there are two black wedges pointing inwards from the indistinct submarginal line, but occasionally one, or more rarely both, may be absent. (Plate [14], Figs. 3 ♂ and 4 ♀.)
The caterpillar is green, with two series of white spotted black marks, the line below these is yellow, and that lower down on the side is bright red; the spots between the lines are white, encircled with black. From April to May it feeds, often in the sunshine, as well as at night, on restharrow, thistles, stonecrop, groundsel, dock, in fact on almost all low-growing plants, as well as the foliage of some trees. The caterpillars of this and the next species are exceedingly pretty creatures, and are sure to attract attention whenever met with. Dr. Chapman notes that the caterpillar will feed on stale leaves.
The moth emerges in the autumn, and seems to be on the wing until quite late in the year, and is seen again as early as March, and thence on until May. One male and two females captured at sugar, March 12 and 13, were placed in a glass cylinder with various food plants, and a sprig of sallow catkins, moistened occasionally with syrup, afforded nourishment for the moths every evening. On April 13, two batches of eggs were noted on nettle, but these were not fertile. On April 15 and 20 pairing took place; and by May 3 over three thousand eggs had been deposited. On May 13 the two females, being still alive, were set at liberty (Goodwin).
Although it certainly appears to be less frequently seen in the south than northwards, the species is known to occur pretty well all over England and Wales. In Scotland, where it is generally commoner than in England, except perhaps in the
northern counties of the latter, its range extends to the Orkneys.
Abroad, it is found throughout Europe (except the most northern parts); Asia to Japan; and the Canaries.