The Purple Emperor (Apatura Iris)
On account of its large size and the beautiful purple sheen over its brownish-black velvety wings, this butterfly (Plate 29) is always counted a prize by the collector. It is, however, only the male that dons the purple, and he only when seen from the proper angle. The female is without the purple reflection and her wings are browner, but the white spots on the fore wings and the white bands on the hind wings are rather wider than those of the male. Above the anal angle of the hind wings, in both sexes, there is a black spot, ringed with tawny and sometimes centred with white, and a tawny mark on veins 1 and 2. As will be seen on turning to the figures on Plate 31, the under side of this butterfly is exceedingly pretty. On the same plate there is a figure of the rare variety known as iole (for the loan of which I am indebted to Mr. Sabine), in which most of the white spots are absent or obscured. Intermediates between this extreme form and the type also occur, but all such aberrations are uncommon.
The egg (Plate 28) may be looked for in August on the upper surface of a leaf of the sallow (Salix caprea). According to Buckler, it is pale olive green in colour, and cylindrical in shape; the height from base to top being about equal to the width through from side to side. It has about fourteen ribs.
The caterpillar in October, just before hibernation, is dingy green roughened with numerous whitish warts from which arise short bristles, some of the latter appearing to be tinged with reddish, and those along the sides longer than those on the upper part of the body; the straight lines along the back and the oblique ones on the sides are yellowish. The head and the two horn-like projections, reminding one of the horns of a slug, are reddish-grey and covered with warts and bristles. The anal points (tails), which lie close together, are tipped with reddish. It should be mentioned here that on emerging from the egg the young caterpillar is without horns; these are not developed until the first skin is thrown off, which event happens from eight to twelve days after hatching.
The full-grown caterpillar is green, merging into yellowish towards the anal points (tails); the oblique stripes on the sides are yellowish, edged with reddish. The individual depicted on the plate took up a position for change to the chrysalis on June 6. It spun a mat of silk to the under side of a sallow leaf, and the next day it was found suspended by the claspers, which were grasping the silken mat. On the fourth day the chrysalis was fully developed, and from this a male butterfly emerged on June 24, an unusually early date.
The chrysalis is whitish, more or less tinged with green, but having the oblique lines on the sides whitish; the veins of the wings also show up whitish.
The caterpillar was well known to entomologists in this country as far back as 1758, when, in May, four were obtained from sallow at Brentwood in Essex. It usually occurs on sallow, but an instance is recorded of it refusing to eat this plant; it would probably have starved if willow, upon which it fed up, had not been substituted. A full-grown caterpillar was on one occasion found at Raindene in Sussex on poplar, which is a well-known food of the species on the Continent. Now and then a full-grown caterpillar has been met with in October, and Buckler reared two in the autumn from the egg almost to the chrysalis stage, but they died before the change was effected.
As befits his rank, the Emperor has lofty habits, and after quitting the clump of sallow bushes, among which its transformations from egg to the perfect insect were effected, it resorts to the oak trees, around which it flies in July, and, when not so engaged, rests on a leaf of the higher branches. To capture the butterfly, when seen at such times, is not altogether an easy matter, as for the purpose the net must be affixed to the end of a pole about 14 or 15 feet in length. The insect’s rather depraved taste for the juices of animal matter, in a somewhat advanced stage of decay, is a fact well known to the professional collector and others who have taken advantage of it to the monarch’s destruction. This method of attracting a butterfly for the purpose of capture is, however, not exactly to be commended. It surely is a greater pleasure to show one’s friends a single specimen that has been captured by dexterity with the net, than to exhibit fifty that were secured by a device which is not only unsavoury, but unsportsmanlike. The female, however, is not to be allured; she must be sought among the sallows, and when seen is not easy to net, as she skims away over the tops of the bushes and is difficult to follow.
Although most certainly not so common or so generally distributed as in former times, the butterfly still occurs in the larger oak woods in most of the midland, western, and southern counties of England, but is, perhaps, most frequent in Lincolnshire and Northamptonshire. In Wales it is found in Monmouthshire. It has not been recorded from Scotland, and only doubtfully from Ireland.
In Central Europe it is often abundant, and its range extends eastward into Amurland, Central and Western China.
Now follow seventeen butterflies of the sub-family Nymphalinæ.