Pupa

“ The period of transformation being come, the pupa goes to the water-side, and fixes on a plant, or sticks fast to a piece of dry wood, in which position it remains for some little time, when the skin of the nymph splitting at the upper part of the thorax, the winged insect issues forth gradually, throws off its slough, expands its wings, flutters, and then flies off with gracefulness and ease. The elegance of its slender shape, the richness of its colours, the delicacy and resplendent texture of its wings, render it a beautiful object. ”

“ The pupa, or nymph, differs from the larva by its much shorter, compressed form; by being encased in a remarkably hard shell; and by the antennae approximating in form to those of the adult. It has short wing-pads at the sides of the body; the front legs are remarkably powerful, and the creature is capable of moving about; the imago escapes from the pupa by the splitting dorsally of the middle of the thoracic segments. ”

“ Through this rent the tail of the pupa is brought and firmly anchored in the silk by a few vigorous strokes, the insect hanging meanwhile to the skin which has not been quite cast off on the reverse side to the rent. When thus firmly attached to the silken pad, the pupa shakes itself entirely free, whirling itself round and round until the old skin is dislodged from the silk and falls to the ground. The two usual varieties of pupæ are shown at Figs. ”

“ But the escape of the pupa, when about to undergo its last metamorphosis, is as interesting as the fact of its closing the shutters to announce its own death. It is provided with a pair of hooked mandibles, with which to gnaw through the grating, and no sooner have these accomplished their purpose than they fall off, and the pupa takes its last shape of a four winged fly, as represented in the cut. ”

“ Furthermore, the pupa, though one in the strict sense, is capable of great freedom of movement, its head, mouth-parts, antennæ, legs and wings, ensheathed by the cuticle, being freely movable, and not rigidly attached to the body. ”

“ Fig. 79.—Forked spine of Limnobia, enlarged; the dark lines show air-tubes.
The pupa is quite as remarkable as the larva, though the breathing apparatus does not assume the form of spines, but consists of two ‘trumpets,’ [169] one on each side of the head, as is the case with the pupae of gnats, using that term in a wide sense. The colour is a greenish-brown, dotted with black. The abdomen is capable of a good deal of motion from side to side; and by this means the pupa can raise itself to the surface of the water to take in a supply of air. ”

“ In the lower families the pupa (fig. 1, c) is only incompletely obtect, and a greater number of abdominal segments can move on one another. The seventh abdominal segment is, in all female lepidopterous pupae, fused with those behind it; in the male “incomplete” pupa this becomes “free” and so may the segments anterior to it, in both sexes, forward to and including the third. The presence of circles of spines on the abdominal segments enables the “incomplete” pupa as a whole to work its way partly out of the cocoon when the time for the emergence of the imago draws near. ”

“ In a few seconds the pupa makes several slow, but powerful, respiratory efforts; during which the abdominal segments become more contracted along their under surface, and the wings are much enlarged and extended along the lateral inferior surface of the body, while a very transparent fluid, which facilitated the slipping off of the skin, is now diffused among the limbs, and when the pupa becomes quiet dries, and unites the whole into one compact covering. ”

“ The pupa is very short, and is furnished with two clubbed horns on the thorax for respiration. Its abdominal portions are retained within the old larval skin, thus keeping it firmly anchored to the log. The perfect insect emerges from a rent in the thorax of the pupa, groups of exuviæ being of common occurrence under the bark. The sexes differ considerably, the individual figured (Fig. 4) being a male; the female is slightly larger, and much more stoutly built ”

“ In the damp earth which the pupa requires the above-described hooks fulfil a purpose, unexpected by us, but, at the same time, of great importance. The skin of the pupa is very delicate. Lying on damp earth, it could hardly escape injury, and the weight of the body might easily give it a distorted shape. ”

“ A, S. pecuarum, pupa; a, b, c, adminicula.—After Riley.
There are also secondary adaptive structures peculiar to the pupa, which are present and only of use in this stage. These are the thoracic, spiracular, or breathing appendages of the aquatic Diptera (Fig. 583) , the various spines situated on the head or thorax, or on the sides, or more often at the end of the abdomen, besides also the little spines arranged in more or less circular rows around the abdominal segments, the cocoon-breaker, and the cremaster of many pupæ. ”

“ A gnat pupa swims through the water by powerful strokes of its abdomen, while the caddis-fly pupa, in preparation for its final ecdysis, bites its way out of its subaqueous protective case and rises through the water, so that the fly may emerge into the air. Some pupae are thus more active than some nymphs; the essential character of a pupa is not therefore its passivity, but that it is the instar in which the wings first become evident externally. 429 The division of the winged Hexapoda into Exopteryga and Endopteryga is thus again justified. ”

“ The pupa (Fig. 5b) is very elongate, reposing in one of the burrows, previously constructed by the larva. It probably breathes by means of its spiracles, as no special organs of respiration are visible. The perfect insect appears in a short time, flying sluggishly in the sunshine, the female possessing an enormous abdomen, which almost incapacitates her for aerial locomotion; in other respects she resembles the male, which is the sex figured (Fig. 5) . ”

“ THE PUPA OF INSECTS.
In this stage the insect is in profound repose, as if resting after its long meal, the better to enjoy its active, sportive - 69 - days—the joyous honey-moon—soon to come. In this stage the insect may look like a seed; as in the coarctate pupa of diptera, so familiar in the "flax-seed" state of the Hessian-fly, or in the pupa of the cheese-maggot or the meat-fly. This same form, with more or less modification, prevails in butterfly pupæ, called, because of their golden spots, chrysalids, and in the pupæ of moths. ”

“ The pupa is unlike any other Lepidopterous pupa, but is similar to those of Trichoptera; neither the head nor the appendages are glued to the body or to one another, but are free, so that the pupa can use the appendages to a considerable extent; it is furnished with enormous mandibles (Fig. 211, C, D) , which are detached and shed after emergence. [343] In the interval between {437}the larval period of feeding and the imaginal instar, the phenomena of life are essentially like those of Trichoptera. The larva has not been at all satisfactorily studied ”

“ The pupa either shows the appendages of the perfect insect, though these are encased in a sheath and adherent to the body, or else it is entirely concealed within the hardened and contracted larval integument, which forms a barrel-shaped protecting capsule or puparium. ”

“ When the pupa had slept the appointed time, the animal, still resident within the habitaculum formed by the larva, was found to open the carina by the motion of its head, and prepare to receive the winged male. Here, therefore, we have an animal which in its adult state is for ever excluded from the light, and never even beholds the mate to which it is indebted for its progeny. ”

“ The water is periodically circulated in the tunnels by violent movements on the part of the pupa. About a day before emergence the insect assumes a peculiar silvery appearance, which is occasioned by the presence of a large quantity of air between the imago and its pupa skin. This air has been first imbibed by the gills and afterwards expelled through the spiracles of the enclosed gnat, thus inflating the skin of the pupa, and helping to buoy it up during its last and most important transformation. ”

“ Characters from the larva and pupa.
Larva depressed, kaned; has sixteen feet, lives through one or more winters, never rolls itself in a ring when touched, feeds on the solid interior woody parts of vegetables; pupa changes in a tough cocoon, in which are interwoven particles of the larva's food; it has a double row of small raised denticulations on each segment of the abdomen, which give it partially the power of locomotion. ”

“ From the account thus given of the contents of the pupa-case, it will be apparent that the pupa possesses, when perfect, all the organs of the complete insect, head, eyes, antennæ, wings, legs, &c., and is in fact only different from it in that it is still inactive to a great extent, and still a prisoner within its cell of membrane. [232] In a little while the bonds which keep it in the tomb will be broken, and the slumberer shall rise a glorious creature to the enjoyment of all the happiness of a new condition of existence. ”

“ It does not reproduce a crab-stage, nor has there been any stage in the ancestry of the butterfly when they lived throughout life in pupa-houses. The pupa is simply a later adaptation in the development of the butterfly, a protective stage in which it accomplishes the transition from the caterpillar-form in much the same way as the young bird develops under the protection of the hard egg-shell. ”

“ The pupa is rather attenuated, dark-brown, and much pointed at its posterior extremity. It is found buried about an inch in the earth, and the moth appears in a month's time. This insect varies much in intensity of markings. The males are generally considerably darker than the females, but are more certainly distinguished by their attenuated bodies. ”

“ In fact, it is difficult, in many instances, from inspecting an individual to say what stage of its progress it has reached. The final state, however, may usually be determined by the full development of the wings and tegmina; these members exist in the pupa only in a rudimentary condition. The pupa is never quiescent, but moves about and takes food. Not only do the larva and pupa resemble the perfect insect in external appearance, but it is likewise found on dissection that their internal organisation is similar. ”

“ The larva without legs, a distinct head being often absent. The pupa inactive, the limbs of the imago firmly attached to the body, but plainly visible. Among the majority of species included in this Order the larval skin is not cast away, but envelopes the insect in a hard shell; the true pupa is consequently only visible on the removal of this covering, when it is found to closely resemble those in which no such arrangement occurs. ”

“ In the case of insects with complete metamorphosis, the young hatches as an active grub or worm-like feeding larva which increases in size, casting its skin or molting several times in its growth. Finally after the last larval molt (fig. 53) called pupation the insect appears in a quiescent non-feeding stage called the pupa (fig. 54) , and encased in an extra thick and firm chitinous exoskeleton. The immovable pupa is sometimes concealed underground, sometimes enclosed in a silken cocoon spun by the larva just before pupation, or is in some other way specially protected. ”

“ Before the pupa has a chance to make its way out, and so destroy the long, silken thread, the man who has taken such care of the worm drops the cocoon into boiling water, which kills the pupa at once. Then the precious silk thread is carefully unwound on to little spools, and is ready to be made into thread or spun into silk. ”

“ During the pupa stage Anopheles, like the pupa of other insects, takes no food.
The pupa is something like a tadpole, with its tail bent under its body and flapping up and down, instead of from side to side. The whole pupa is enclosed in a thin semitransparent membrane, through which the organs of the adult can readily be seen. As it grows older its colour darkens. Until about the time when it will give rise to the fly, the pupa floats quietly at the surface, breathing through its respiratory trumpets. ”

“ Pupa (Jaminia) muscorum.—Common, especially on sandy soils near the sea. Mouth nearly circular, whereas in the two former species it [Pg 49] is horseshoe-shaped. The lip is thin and not reflected.
The genus Vertigo (i.e. twisted, the Latin equivalent of the Greek Helix) contains shells even smaller than the Pupæ, about the size of a pin’s head.
Vertigo (Alæa) antivertigo (i.e. not reversed or sinistral, as are V. pusilla and V. angustior) . Semi-transparent, glossy, horn-colour, with denticles (as have all except V. edentula and V. minutissima) . Found in nearly all counties in moist places. ”

“ At the time of emergence, the pupa secretes a fluid which escapes from the mouth and by moistening the cocoon softens the glue-like material which binds together the threads, thus making it possible for the freshly emerging moth to crowd its way between the fibres, and thus secure its freedom. ”

“ Pupa (210 sp.) abounds most in Europe and the Arctic regions, but has a very wide range, being scattered throughout Africa, continental India, Australia, the Pacific Islands, North America to Greenland, and the Antilles; but it is absent from South America, the Himalayan and Malayan sub-regions, China and Japan. An extinct species has occurred abundantly in the carboniferous strata of North America. About 160 additional species have been described. ”