Inskcts.] 



MUSEUM OF ANIMATED NATURE. 



359 



silken threads which readily adhere, till at last a 

 little silken cone is produced, into which the cater- 

 pillar pushes Its hinder pair of pro-legs (those on 

 the last ses^ment), which become entangled and so 

 fixed amidst the threads ; it then permits itself to 

 hang down with the head lowermost. In a short 

 time it begins to bend its back, bringing the head 

 near the attached pro-legs, and after continuing for 

 some time in this attitude it straightens itself and 

 repeats the same action. In about twenty-four 

 hours the outer skin begins to split down the back, 

 and the fissure is enlarged by the swelling and 

 pressure of the chrysalis, till at length the head 

 and adjoining portion of the suspended chrysalis 

 become disengaged, the skin shrivelling up into a 

 bundle surrounding the tail. This, however, has to 

 be thrown off, and at the same time the chrysalis 

 has to avoid disengaging itself from its mooring of 

 silken threads from which it hangs ; for, be it re- 

 membered, it was by its hind legs that.it attached 

 itself. To eiFect this operation, one of no little 

 nicety, it seizes on a portion of this shrivelled skin 

 between two segments of its body, holding it as 

 with a pair of pincers, and thus destitute of limbs 

 supports itself till it withdraws the taH from the old 

 useless skin which sheathed it ; it then, still clinging, 

 elongates the rina:s of its tail as much as possible, 

 and seizes a higher portion of the skin, and in this 

 manner climbing backwards as it were upon its 

 exuviae, it repeats the manoeuvre till the extremity 

 of the tail presses the silk, to which it immediately 

 adheres by means of a number of hooks provided 

 for the purpose. Still these exuviae encumber it, 

 and hang in contact with it ; curving its tail in such 

 a manner as partly to embrace the shrivelled skin, 

 it whirls rapidly round, jerking violently, and at 

 length succeeds in disengaging the slough from its 

 fastenings and throwing it to the ground. In a 

 short time the chrysalis hardens (for at first it is 

 very soft) and shows through the outer case the 

 wings, antennae, eyes, and legs of the perfect insect. 

 It now passes into a sort of torpid state till the time 

 arrives for the exit of the perfect butterfly from its 

 case. 



That the organization of the perfect butterfly or 

 moth was developed under the external aspect of 

 the caterpillar, though the different parts were then 

 in embryo, was known to Swammerdam, and also to 

 Malpighi and Reaumur, and has been demonstrated 

 by dissections, which, on account of the delicate 

 nature and softness of every portion of the internal 

 structure, are not easily accomplished. Swammer- 

 dam hardened the caterpillars by immersion for 

 some hours in spirits of wine and vinegar mixed 

 together. Fig. 3531 represents the upper and under 

 surface of the butterfly in embryo, within the mask 

 of the caterpillar. The wings, antennae, and trunks 

 are spread out to show them. 



The duration of the pupa or chrysalis state of 

 existence varies in different species, and even in 

 the same, the escape of the perfect insect being 

 retarded by cold, and accelerated by warmth— a 

 wise provision as it respects the safety of the ma- 

 tared insect. When ready for exclusion the butterfly 

 bursts the skin of the chrysalis now to be thrown 

 off which covers the thorax, and emerges feeble 

 and languid, with wings crumpled up into small 

 bundles. Soon, however, the body acquires strength, 

 the fluids circulate, air is driven through the nervures 

 of the wings, these gradually unfold, and the crea- 

 ture quivers then as it feels its growing powers. 

 At length, in the perfection of strength and beauty, 

 it leaves its sordid mummy-case behind, soars aloft, 

 and seeking the flowers of fields and gai'dens com- 

 mences a new existence. 



Such is the progress of the butterfly from the egg 

 to its perfect condition ; from — 



" The worm, — a tliine tliat crept 

 On tlio bare earth, then wrought a tomb and slept," 



to the hovering " Psyche." 



Fig. 3532 represents the caterpillars of the Admi- 

 rable Butterfly (Vanessa antiopa) : a one of them 

 weaving its button of silk ; b, one suspended by its 

 hinder pro-legs from the silk button ; c, one bending 

 itself in order to split the old skin. 



Fig. 3533 shows at a the suspended caterpillar of 

 Vanessa antiopa splitting its skin for the evolution 

 of the chrysalis ; at b the head of the chrysalis 

 emerging, and at c the same process farther ad- 

 vanced ; d, the perfect pupa. 



Fig. .3.534 represents the pupae of the small Tor- 

 toiseshell Butterfly (Vanessa urticaf), suspended to 

 the silk by their terminal hooks: a, a front view ; 

 h, a lateral view ; c, a magnified view of the terminal 

 hooks; d, the old skin shrivelled up and rejected. 



Some caterpillars secure themselves still more 

 ingeniously, and frequently in a horizontal position, 

 by binding themselves to their support by a belt of 

 silken threads round the body. Such is the case 

 with those of the hair-streak butterflies (Theclae). 

 The caterpillar, having first secured itself at the tail 

 draws back its head, and pushing out its spinneret 



makes a sort of loop, or girth, of silk, fastened at 

 each end ; when this is sufficiently strong it insinu- 

 ates itself under it, and the cincture embracing the 

 middle of the body binds it securely. In this posi- 

 tion it awaits the ensuing change. The caterpillar 

 of the black-veined white butterfly constructs a 

 I similar cincture, but in a manner somewhat differ- 

 ent, being of an elongated form and very flexible ; 

 it bends its head back, and by throwing threads 

 across its body, each duly fixed to the branch (the 

 under side of which it occupies), it binds itself 

 secure. Fig. 3533 shows a, the caterpillar of the 

 black-veined white butterfly spinning its suspensory 

 hand; b, the chrysalis horizontally bound to a 

 branch ; c, the butterfly (Pieris Crategi) smaller 

 than in nature. 



The caterpillar of the splendid swallow-tailed 

 butterfly (Papilio Machaon) constructs a loop also 

 for its suspension ; having secured its caudal ex- 

 tremity, it forms a suspensory girdle, using its hooked 

 limbs in keeping the threads on the stretch till fifty 

 or sixty are fastened ; the loop thus formed is about 

 twice the diameter of the body, and this it slips over 

 its head to wait, suspended, its approaching meta- 

 morphosis. This caterpillar has two retractile horns 

 on its head, the use of which is not very clear. 

 Fig. 3536 shows, a, the caterpillar of the swallow- 

 tailed butterfly weaving its suspensory cincture; b, 

 the caterpillar suspended waiting its change ; c, the 

 chrysalis suspended in a similar manner. 



By means of their silken threads many caterpil- 

 lars, like the spider, can lower themselves at plea- 

 sure to the ground, and remount their slender 

 cordage. Their method, however, differs from that 

 of the spider, the spinnerets of which are at its 

 hinder extremity ; the spider drops with the head 

 downwards and turns round to remount, which it 

 does by means of its triple-clawed limbs, coiling up 

 the line as it proceeds ; the caterpillar, on the con- 

 trary, drops with the caudal extremity downwards; 

 the spinneret being near its mouth, and having short 

 limbs, the anterior ones being smooth and horny, it 

 cannot ascend with great dispatch : its plan of 

 operation is to grasp the line with its posterior pro- 

 legs, and at the same time raise its head ; then using 

 the other pro-legs it ascends step by step. 



Fig. 3537 shows two caterpillars of the Emperor 

 moth (Saturnia Pavonia), one descending, the other 

 ascending its silken thread — in comparison with the 

 garden-spider (Epeira diadema) ascending. 



The geometrical caterpillars, when at rest, have 

 always a thread secured, by which to drop when 

 alarmed. Fig. 3538 shows the caterpillar of the 

 Brimstone moth thus prepared : a, the caterpillar 

 in its resting position, with the thread fastened ; i, 

 the moth (Humia cratsogata) ; c, the eggs; d, a 

 young caterpillar. 



In some instances, caterpillars have been ob- 

 served to use their silk-apparatus with great address 

 under peculiar circumstances. Rosel saw the cater- 

 pillar of the goat-moth, when confined in adrinking- 

 glass, contrive to escape with what we may term 

 great ingenuity ; it applied the adhesive silk-gluten 

 to the glass, and so spun a succession of ladder-steps 

 from the bottom of the glass to the top, ascending 

 them as it continued its labour. Fig. 3539 shows 

 the caterpillar of the goat-moth thus making its 

 escape. 



But the silk of caterpillars serves for other and 

 more important purposes; for, as we have said, 

 some shroud themselves in a cocoon, and thus en- 

 veloped undergo their last change; while others 

 weave tents and habitations, in which to dwell. 

 Among the former we may instance the silk-worm 

 or caterpillar of the Bombyx mori ; see Fig. 35-10— 

 a and b, the male and female moth ; c, the eggs ; 

 (/, the pupa removed from the cocoon ; e, the cater- 

 pillar ; and Fig. 3541, the caterpillar. 



In this species the caterpillar is about eight 

 weeks in arriving at maturity, during which period 

 it changes its skin four or five times, and ultimately 

 prepares for assuming the pupa state. It now pre- 

 pares a nest of silk, or cocoon, the whole of which 

 is composed of a single thread, arranged in two 

 modes. To form the exterior envelope, the cater- 

 pillar, having fixed upon a space between two 

 leaves or two stems, or other convenient site, draws 

 a thread from its spinneret and fixes it to an adjoin- 

 ing surface ; it then conducts the, thread to another 

 point and there secures it, and this it continues, 

 drawing the threads from point to point, iii various 

 directions, until it has surrounded itself with a 

 loosely spun maze, the scaftblding for the support 

 of the interior cocoon. Fixing itself by its pro-legs 

 to some of the surrounding threads, it bends its head 

 from side to side, and spins a layer of silk-threads, 

 to which it incessantly adds until it is sufficiently 

 deep; it then shifts its position, and repeats the 

 operation in another place, and so on, repeating its 

 labours till the cavity is reduced to the proper size. 

 Hence, therefore, the cocoon is not formed of a 

 thread wound round and round the caterpillar, but 

 backwards and forwards, in a series of zigzags, so as 



to form a number of separate pads or cushions. The 

 length of the thread composing the inner or true 

 cocoon, without including the exterior case, is not 

 less than 900 or 1000 feet ; but so great is its tenuity 

 that the threads of five or six cocoons require to be 

 put together to form one of sufficient thickness for 

 the working of the manufacturer. The thread of 

 the inner cocoon alone is valuable ; the outer tissue 

 is too much interwoven to be wound off. We must 

 add, that the chamber of the true cocoon, in which 

 the pupa is housed, is lined with a tapestry of silken 

 threads gummed to each other, so as to form a 

 i uniform surface ; this appears to be effected by 

 drawing from the spinneret a more delicate silk, 

 and then uniting the fine threads with gum or fluid 

 silk, given out in sufficient quantity to bind them 

 all together. 



Here, then, in a shroud of pale yellow glossy silk, 

 the caterpillar becomes a pupa ; and here, if per- 

 mitted, the pupa throws ott her last investment, 

 and emerges a perfect moth. But the question now 

 is, how is the moth to get out of the silken tene- 

 ment in which while a caterpillar she had locked 

 up herself, leaving no aperture ? The moth makes 

 her way out by destroying the continuity of the 

 silken threads at one end of the cocoon by means 

 of a liquid solvent discharged from its mouth ; it 

 then presses forward, and the cocoon opens. The 

 latter, however, is now utterly spoiled for all useful 

 purposes, and hence the breeders kill the pupa by 

 exposing the cocoon to a certain degree of heat.* 



In like manner the puss-moth (Oerura vinula) 

 opens its cocoon, composed of particles of wood and 

 sand, cemented together by a sort of gum or fluid 

 silk, which hardens into a mass. Fig. 3542 repre- 

 sents the cocoon of the puss-moth ; the interior of 

 which is occupied, in this specimen, by several co- 

 coons of a parasitic ichneumon (Opliion vinulae), 

 the caterpillars of which had preyed upon the pupa 

 of the moth, and then woven in her tenement their 

 own cocoons. 



In Bengal, the caterpillar of a moth, the Phalaena 

 paphia, which feeds on the jujube-tree leaves, pro- 

 duces a coarse silk, known as Tusseli silk, from 

 which a dark coarse cloth is manufactured of a very 

 durable quality. 



The Arrindy silk-worm, or caterpillar of the Pha- 

 laena Cynthia, produces threads of so soft a texture 

 that it cannot be unwound, but is spun into thread 

 like cotton. From this is manufactured a cloth of 

 loose texture, but of great durability. Neither of 

 these moths has received any attention from Euro- 

 pean silk-growers. 



A very curious cocoon is spun by the caterpillar 

 of the Emperor Moth (Saturnia Pavonia), a large 

 and splendid species ; the caterpillars are repre- 

 sented at Fig. 3343. They spin a cocoon of a 

 pyriforra shape, of strong silk, so thickly interwoven, 

 that the tissue has the appearance of damask or 

 leather ; the apex of this cocoon is open, a narrow 

 circular aperture being left, round which converge 

 stiff threads of silk, gummed together, needle- 

 shaped, and almost as elastic as whalebone. This 

 arrangement prevents the intrusion of depredators. 

 But, as if to make the cocoon doubly secure, within 

 the aperture the caterpillar constructs a sort of 

 dome, which acts as a barrier, should the entrance 

 be forced. The cocoons of the caterpillar of the 

 Emperor Moth are represented at Fig. 3543, cut 

 open to show their structure. 



A very different structure of cocoon is prepared 

 by the caterpillar of the beautiful Cream-spot Tiger- 

 moth (Arctia villica), which lies in the pupa or 

 chrysalis state only about three weeks, and therefore 

 does not require a strong and substantial covering. 

 It consists of a maze of threads, loosely surrounding 

 the pupa, which may be discovered through the 

 loose and light envelope. The cocoon of Arctia 

 villica is shown at Fig. 3344. Thatof another species 

 still lighter and more elegant is seen at Fig. 3543. 

 In this the threads form a fine network, like delicate 

 gauze, investing the pupa within. 



Of the caterpillars which weave tents in which 

 multitudes cluster together, all assisting in the struc- 

 ture of their common dwelling, we may notice the 

 small Ermine Moth (Yponomeuta evonymella), 

 which sometimes abounds in myriads, stripping the 

 hedgerows of foliage ; these caterpillars are gre- 

 garious, and weave filmy webs, with which we have 

 sometimes seen the naked hawthorns festooned. 



Having consumed all the provisions in the neigh- 

 bourhood of their encampment, and the leaver 

 enclosed within their tent, they all change the;^ 

 quarters, and construct another encampment. The 

 Lackey Moth (Clisiocampa Neustria) is also gre- 

 garious, and spins tents in which extensive colonies 

 reside, often to the injury of the fruit-trees which 

 they infest. 



Some caterpillars, as those of the Browntail Moth 



* Reaumur was of opinion that the moth rasped her way out by 

 using her eyes as a file, and thus opened a pas.sage through the cocoon. 

 Mr. Swayne denies that the threads arc brolien at all, either by a 

 solvent or by nling : and affirms that he has succeeded in unwinding 

 a whole cocoon from wltich the moth had escaped. 



