The largest butterfly found in the Islands, measuring from four to four and a half inches across the wings.
The larva is very bright in colour, having transverse bands of blackish violet, gold, and white alternately. It has four black horns or fleshy spikes along its back, and when full grown measures about two inches in length, and it is rather stout and smooth. The pupa, green when first turned, and suspending itself by the tail only, has a bright gold band half-way round its base, and a series of gold spots encircling its head. Shortly before emerging to a butterfly, it turns to a dark brown. The caterpillar never suspends itself to the plant on which it feeds, but goes to some of the higher grasses near it, or it prefers still better a mallow plant, from the leaves of which as many as sixteen beautiful bright green and gold chrysalides have been seen hanging, forming quite a picture under the illumination of the glorious sun of Teneriffe. It lives and feeds gregariously on the “Arbol de Seda,” [4] a plant bearing a very bright red and gold flower. Many specimens were reared from quite small caterpillars in the breeding-cages. They were easy to keep, but especial care must be taken in providing them with fresh food, and great attention ought to be paid to ventilation, or some disappointment may be experienced in the number that die during the pupa state for no apparent reason. A little of the morning sun is beneficial to them, as they are found, when in a natural state, in the most sunny localities.
[4] Asclepias cuvassavica.
A brood seems to emerge about every three months in most years from February to September. The butterfly frequents flower-gardens and fields near the coast, not often being found more than seven or eight hundred feet above the sea. It is of a rich orange tawny colour, rather heavily veined with black or dark brown. All four wings have a broad black border, with two lines of whitish yellow dots along the margin. There is a large apical patch of blackish brown on each fore-wing, with seven large yellow and white spots on the tip. There is not a great difference between the upper and the under side, except that on the latter the white marginal spots are larger, and there is more white on the black-feathered body.
The insect looks splendidly bright and flashing as it soars along with a steady flight from tree to tree on the “Carretera,” and it must be quickly netted, or it soon rises out of reach. These butterflies are distasteful to birds, as also are the three following varieties belonging to the same family. For this reason the family of Danais is “mimicked” by butterflies of other species, the butterfly next described (Danais Chrysippus) being, for instance, copied closely by several African and Indian species of butterflies and even some moths.
The Danais Plexippus is a very common butterfly in North America, and has within the last few years become widely dispersed, some specimens having been found in England in 1877 and subsequently.
DANAIS CHRYSIPPUS.
Plate II.—Fig. 2.
This butterfly is widely dispersed over Europe, Asia, and Africa, but it is not found in England. It is of the same colour as the last described specimen, but is not so large, measuring in expanse from two and a half to three and a half inches. The tips of the fore-wings are broadly marked with black, shading off to brown, crossed with a band of white spots. Four of these spots are of a quadrilateral form, and much larger than the rest. The outer margins of all four wings are bordered with black, freely dotted with white. There are three black spots on the centre of the hind-wings of the female; the male has four, the fourth, which is largest, being placed under the principal vein. The under is similar in markings and colouring to the upper side, but the white spots are more pronounced, and the tawny yellow somewhat paler; the apex of each fore-wing is moreover tipped with yellow, instead of being black like the upperside. The larva is very similar to that of the Plexippus. It is somewhat smaller, however, has six fleshy horns instead of four, and the transverse gold and black stripes are interspersed with white spots instead of stripes. It feeds gregariously with the above variety on the “Arbol de Seda,” and appears at the same time, in the same locality, and in equal numbers. When it changes to the pupa state it resembles closely the bright green chrysalis of its companion, only it is not quite so large.