True Tales of the Insects

Fig. 36). Linnaeus, and all the writers of the last century, regarded the species of the genus with which they were acquainted as butterflies, including them in the great group Papilio, on account of the clubbed structure of their antennae. At the beginning of the present century, when this group was broken up, the genus Castnia was

established; though Fabricius still retained it among the butterflies. But when the antennae are carefully examined, they do not exhibit the real Rhopalocerous structure. In like manner, the Castnians differ from other groups of Heterocerous lepidoptera, in the complicated arrangement of the veins of the wings, and in various ways.

In general appearance they vary much, but, typically, they have large wings, with loose and remarkably large scales, and a position in repose deflexed or incumbent, being furnished with a wing-guide or guides; and the antennai, though club-like at the tip, are generally long and more or less supple. All these characters are constant, and are Heterocerous characters. As a rule, the head is broad, and the body large and somewhat pointed. The Castnians resemble butterflies in this particular, in their evidently diurnal habits, as evinced by the brilliancy of their colours. They fly in open day, during the heat of the sun, with incredible rapidity, loving to rest wide-spread on the earth or on trunks of trees, and at certain hours pilfering the flowers of their sweets, and frequenting the inlets of thick forests, where they rest occasionally on the tree trunks, far above the ground. Numerous species are reckoned within their number, many of large size, and generally adorned with beautiful colours, a rich effect heightened by the metallic gloss of the prominent scales with which most of them are covered. In respect of colour the sexes may differ much.

DAY-FLYING MOTHS.

Turning to their preparatory stages, the larvae are endophytous, boring, with strong mandibles, the interior of stems and roots of cacti, of orchids, and other habit similar to that of the caterpillars plants—a of the Hetero- '^^^ cerous Cossians and Sesians, but which, though found in butter-tlies, is very exceptional. Likewise they are provided with the ordinary horny piliferous spots or tU" bercles that characterize Heterocerous larva;, "^ and have a horny anal plate,

Fig. 36.— Cast7iia cudesmia, from Chili. whereas butterfly larvae rarely possess these warts, but are frequently beset with close-shorn bristles, springing from the general surface, or from minute papillae. In keeping with all Heterocerous borers, the pupae are supplied with minute

I90 TRUE TALES OF THE INSECTS.

spines on the hind borders of the abdominal joints, affording the pupa power of executing the same manoeuvres as the chrysalid of Sesia, enabhng it to move in the tunnel bored in the tree, and assisting it out of its cocoon. The Castniidae are essentially proper to the warm equatorial regions; their geographical range, in fact, extends only to Mexico and Central and Southern America, while they find their greatest development in Central America and Brazil. The few Castnioides, or species of Megathymus, known, inhabit the southern portion of North America, hailing from the Southern States, from Florida, and from Arizona. The genus Synemon appears to represent the Castniidce in the vast continent of Australia.

The } ^ncca Borer.

Of these aberrant forms Megathymus yiuccc, the Yucca Borer, is one of the most interesting. Although placed with the Castniida?, none the less it has given great trouble to systematists, having been bandied from the butterflies to the moths; and, it must be owned, some still regard it as a genuine butterfly. This species is common in the Gulf States of America over extended regions, where its larva commits serious depredations, of the nature that its popular name implies.

It is a sad-coloured moth, and rests with winors thus differins: from elevated-the typical its antennrt' gene- Castniidce-rally directed forwards; also in smaller wings, in smaller, closer scales, in unarmed hind-wings, and in stiffer, relatively shorter, antennae, it diverges in character from the Castniidas (see Fig. '^'jY Its flight, which is diurnal, is an extremely rapid darting

motion as it passes from plant to plant, principally in open spots; though easily startled, it settles at no great height. During April and May, and earlier, it may often be seen in the morning where the yuccas abound, darting hastily about after its customary fashion, on laying thoughts intent; and as it pauses for a few seconds at one place, it fastens an ^gg to some portion of a leaf. The eggs are laid singly, though more than one may be put on the same leaf They are subconical, smooth, and broader than high, pale green at first, changing to buff-yellow or brown. From the ^gg creature withshortly hatches the larva— a reddish-brown shelters itself in a web betweenpitchy-blackhead—which it startssome of the young terminal leaves. Usually proceedings near the tip of a leaf, working gradually downwards, eating the while, and rolling and shrivelling the blade as it goes. It lives thus among the leaves till about one-fourth grown, when it enters the trunk, com-mencing the devastation for which it is famed. Along the axis the trunk becomes bored and tunnelled out into a cylindrical burrow, wherein the larva makes its home, extending often two or more feet below the ground, and at its upper end lined with silk, generally inter-mingled with a white, glistening, powdery material, soapy to touch, and analogous with that of Hymenopterous and many Homopterous larvae. At what stage of larval development this powder is secreted is not known,

but the full-grown larva is always covered with it more or less copiously, and doubtless it protects the invader against the mucilaginous liquor which the yucca freely exudes on maceration. How many larval moults occur has not been ascertained, but the insect continues in larva till subsequent late winter or spring, and during the coldest weather probably lies in a semi-torpid condition at the bottom of the burrow.

The funnel-like tube outside the burrow, made by the twisting and webbing together of the tender leaves when partially devoured, is quite characteristic of the larva of Yuccse. The tube is, indeed, built and extended often several inches beyond the trunk or stem. From it the builder, especially when young, emerges to feed, and the small amount of matter besides silk used in

its the remnants of leaves and such-like construction-substances— have been obtained and worked into the exterior from the outside. Pupation generally takes place at the top of the burrow, just below the funnellike projection, but without the preparation of a well-formed cocoon. The pupa is of a brown-black, turning paler on the abdomen; all its members are distinctly defined, and, like the mature larva, it is more or less densely covered with a white powdery bloom. In due time the pupa skin is rent, and the imago issues.

The Brilliant UraniidcB.

It has long been a problem with systematic writers what is the true situation in nature of the highly interesting group of insects Uraniidai. Linnasus regarded the more typical species as butterflies, placing them in his great group called Papilio, containing the whole of the day-flying Lepidoptera; Fabricius, who divided the Lepidoptera into genera, even placed the genus Urania at the head of the order, followed by the other genera of butterflies. It may be mentioned that Urania may now be considered as the type of the family Uraniida^, the genus Urania, in more recent times, having been split up into smaller genera. All detail must be omitted of the positions assigned to different members of the group from time to time. The day-flying habits of the insects, together with their airy forms and the extraordinary brilliancy of their colours, naturally led to their being at first classed among the Rhopalocera, or true Butterflies, but later acquaintance with their transformations proves them to belong to the Heterocerous division of the order. Bosiduval describes one as " ce magnifique Lepi-doptere, le plus beau de la creation." They are among the most richly ornamented Lepidoptera of that very brilliant order. It would be difficult for art to effectually

represent the changeable and resplendent golden green of the numerous bars, which contrasts with the velvety black of the wings, and varies with every change of light. It is these splendid tints of green that render them, perhaps, the most charming insects that exist, and has caused them to be named Emeralds; sometimes also they are called Pages. The posterior wings are prolonged into a single elegant pointed tail, closely resembling that appendage in many swallow-tailed butterflies; or there may be present at the hinder extremity of the wings no fewer than three distinct tails, that most remote from the anal angle longer than the others. The typical species of these superb insects are natives of tropical America, where they fly so high, and with such amazing rapidity, that it is almost impossible to catch them, and the only way, therefore, to obtain good specimens is to rear the caterpillar. When at rest, the anterior wings are kept in a flat or horizontal position, though only slightly spread, one peculiarity, amongst many others, in which they resemble the nocturnal Lepidoptera.

Urania Boisdnvalii and Others.

Urania boisdnvalii, which inhabits Cuba, may be considered one of the most beautiful Lepidoptera known.

196

Fic. 38.—Urania boisduvali’, green and

velvety black, from Cuba.

TRUE TALES OF THE INSECTS.

It attains an

expansion of

wing of from

four to four and

a half inches,

with an undulated

hollows

rim, the

of

which are more or

less sparsely tipped

other-with white;

its colours

black

green. While

black of the superior

wise are

velvety and

the

pair of wings is relieved

with golden green transverse lines, and their under

black,

with transverse lines of a

bluish green, on the black

side is nearly all

of the inferior wings we

note a longitudinal broad

discal green band, a mark

easily distinguishing this

beautiful species from all

its congeners. Its head is

small and black, having a

DAY-FLYING MOTHS. i()i

golden green V in the middle; the thorax is green and black; the eye has a black coppery lustre (see Fig. 38).

On approaching from the sea any open sandy shore in the Isle of Cuba a copse wood is perceived, above the coral reefs, forming a close and nearly impenetrable belt, maybe ten or twenty yards wide, and composed of almost one kind of tree, of aspect strange to the European eye, the Coccoloba uvifei^a, the so-called Uvero of the Spaniards. Immediately behind this belt an immense variety of vegetation grows in the parched shrubs in plenty, and what not, insand—seaside general festooned with the flowers of different lovely climbing plants, every object quivering, as it were, beneath the scorching plant of chief interest sun—the to us being that technically titled Oiuphalea triandra.

This, the Cob or Hog-nut of Jamaica, the Avellano of the Island of Cuba, belongs to the family Euphorbiacea:?. Sometimes it reaches the dimensions of a tree, fifteen feet high. The part that concerns us is the leaves great, thick, heart-shaped things of leathery texture, and a scabrous surface, of a pale green. The young leaves, and the leaves of the young plants, although of the same texture and colour, are of different form, being deeply incised. During the heat of the day, on the upper side of the mature entire leaves of this tree, often the caterpillar of U. boisditvalii may^ be discovered torpidly reposing.