K44 



evaporation were the sole operation to which the 

 fupa was sulijoct, there would be sufficient grounds 

 for the theory of evaporation entertained by Swam- 

 ii, i 1 nl. mi, Reaumur, Kirby, and Spence ; but such is 

 not the case, for Reaumur having enclosed a pupa in a 

 stopped glass tube, collected only several drops o 

 water, which were condensed against the sides of the 

 tube, the pupa having only lost one eighteenth part o 

 its original weight. rfence the development of 

 the organs of the enclosed animal, by absorption 

 and assimilation, constitute the great operation which 

 tne pupa has to undergo, and this must, of course, be 

 of equal duration, whether the insect be a large or a 

 small one, although it may be accelerated or pro- 

 longed according to the degree of temperature of the 

 atmosphere. 



In our articles CHRYSALIS and ERIOG ASTER, we have 

 noticed some curious and inexplicable circumstances 

 relative to the retarding of the production of certain 

 individuals for one or more years, although placed 

 in precisely similar circumstances with others which 

 are evolved at the ordinary and stated time. The same 

 fact* have been observed respecting other moths. 



We are now to notice the mode in which the 

 insect emerges from its pupa skin. Ordinarily this 

 is effected as heretofore, in consequence of the 

 increased size of some, at least, of the segments 

 of the body, especially those of the thorax ; and 

 it is now only necessary tor the insect to give to 

 its enclosed body various contortions, when the 

 skin slits generally down the back, and permits 

 the escape of the enclosed insect. In chrysalides, 

 the slit extends gradually down the sides of the wing 

 cases, and on each side of the leg cases, so 

 that the outer skin of the chrysalis may be said to be 

 split into four portions ; on its exclusion, the insect 

 is soft, weak, and covered with moisture. The elytra 

 and the wings, at first, are but of a small size ; their 

 form, however, soon changes, their thickness di- 

 minishes, and their ordinary size is acquired, the air 

 tubes distributed throughout the body, and especially 

 in the wing, performing the important office of infla- 

 tion, and chiefly assisting in effecting the change, so 

 that in a very short period the insect has arrived at 

 its full size, and acquired the utmost perfection of all 

 its organs. 



Fig. 5 1 . Tortoise-shell butterfly just emerged from the c _u / -*i t. 



The wings of lepidopterous insects, as they lie 

 within the pupa skin, exhibit all the future markings 

 cf the butterfly and moth, but of course of a re- 

 duced size. The wings themselves appear perfectly 

 flat, and it is difficult to conceive how these organs 

 expand to their full dimensions, all these markings 

 retaining their relative sizes. The difficulty is, 

 however, remedied on denuding the wings of their 



ECT. 



scales, when their surface is discovered to be entirely 

 formed of an innumerable series of minute wrinkles, 

 giving the wing an elasticity, by which we can 

 stretch them to nearly double their size, by moisten- 

 ing them with water. If we imagine the scales 

 to be placed upon the upper edge of each ridge, 

 and that they increase in size as the wings expand, 

 we shall be furnished with a further clue to the solu- 

 tion of this interesting question, as to the mode of 

 expansion of the wings of the Lepidoptera. 



In the aquatic pupae, which produce aerial insects, 

 it is necessary for the pupa to quit the water previous 

 to putting on the perfect state ; thus the pupa of the 

 dragon fly creeps up the stems of some adjacent plant ; 

 and that of the gnat naif portruding its body above 



Fig. 52. Gnat emerging from its aquatic pupa. 



the surface of the water, the skin splits down the back 

 and the gnat, making use of its pupa case as a boat 

 radually draws itself out of its case, upon which it 

 sits until its wings are expanded. In pupee which 

 are enclosed in cocoons or other cases, different 

 modes of escape are required. How, for instance, can 

 a moth, whose beautiful wings and crested thorax indi- 

 cate no previous struggle, make its way through the 

 cocoon, often as solid as the hardest wood. This is 

 fleeted either by the peculiar construction of the 

 cocoon, or by the operation of some fluid emitted by 

 he insect on its arrival at the perfect state. In like 

 manner the pupae of flies and other coarctate diptera 

 brce off a case, at one end of the dried skin, 

 )y inflating the middle of the head into a large mem- 

 )ranous vesicle ; and the pupa? of the caddice flies, 

 which are inclosed in the case in which they resided 

 whilst larvae, make their way through the net work 

 covering which they had spun to defend its entrance. 

 But the most curious circumstance connected with 

 his subject, is the mode of extrication of the males 

 of the Gall insects (Coccus), the pupa3 of which are 

 strictly coractate, the imago making its escape 

 >ackwards from beneath the flattened skin of the 

 arva, its wings being turned backwards over the head. 

 The development of insects is very rarely attended 

 with those deviations from the ordinary rule, which 

 re sometimes met with in other tribes of animals. It 

 ias, however, been recorded in the Entomological 

 Magazine, No. 12, that a male and female emperor 

 moth (Salurnia pavonia minor) were produced from a 

 ingle larva of an extraordinary size. Kirby and 

 Spence also mention that, according to Kleesius, a 

 erman entomoligist, two specimens of Gastropacha 

 quercifolia (the pine lappet moth), were produced from 

 me pupa, which was large, being full two inches long 

 nd one thick. These circumstances are sufficiently 

 marvellous, but the most marvellous fact of all is that 

 affirmed by Mr. Dale, in the Magazine of Natural 

 History, Nos. 19 and 34, viz., that he "once had a 



