472 



NATURAL HISTORY OF ARTHROPODS. 



FIG. 597. Chrysalis 

 of PupUio '(Suc- 

 cincti). 



systematists as to the value of these peculiarities of the chrysalis in the classification 

 of the butterflies, many deeming the Papilionidae, from their superior size, the posses- 

 sion of four distinct branches to the median nerve of the front wings, 

 and above all the development of the osmateria or scent-organs, to 

 be worthy of the highest rank in the beautiful army of the Diurnae ; 

 while others hold that the suspension of the chrysalis by the tail is 

 evidence of a more advanced condition, the animal having in its de- 

 velopment passed beyond the stage of the girth period, thus claiming 

 that " the Suspensi outrank the Succincti, as the pupa is higher than 

 the larva." Without presuming to settle this vexed question, it is 

 but fair to state that the majority of lepidopterists in Europe and 

 this country favor the latter view, and the able and almost exhaus- 

 tive " Catalogue of Diurnal Lepidoptera," by Mr. W. F. Kirby of the 

 British Museum, is based upon it, the series therein commencing with 

 the Nymphalidae, the Papilionida? being degraded to a position a little 

 in advance of the Hesperidse. Giving no special adherence to either of these methods, 

 the plan followed in the present paper will be the opposite of Mr. Kirby's arrange- 

 ment ; as Mr. W. H. Edwards, who has published the most complete catalogue of the 

 butterflies of the United States, has adhered to the older method, and for the conve- 

 nience of the students of our Lepidoptera, it is best to have some harmonious action, 

 thus avoiding troublesome complications. The duration of the chrysalis, as of all other 

 stages of insect life, is very variable, largely dependent upon climatic and other influ- 

 ences, but it may be said to average about 20 days. Many of these species that are 

 double-brooded go through the winter, however, in this state. 



When the hour of final transformation comes, the sutures of the thorax give way to 

 the pressure from within, the rupture first taking place in the central division. This 

 is followed by other fissures in the sides, an opening is formed, and the imago or per- 

 fect insect, with soft, wet, and undeveloped wings, crawls up the stem of a plant or the 

 trunk of a tree, and, inflating its wings by gentle motion, causes them to expand in a 

 few hours, and is enabled to soar away and enjoy to the full its brief but beautiful 

 existence. 



The perfect stage of the butterfly is so different from those which had preceeded 

 it, that it is necessary to speak of a few of its characters. The head " is composed 

 of three well-marked pieces, viz., the occiput, or basal piece, which lies behind the 

 ocelli ; the epicranium, lying behind the insertion of the antenna?, and carrying the 

 eyes and ocelli; and the clypeus which constitutes the front of the head. The labium 

 or upper lip is small and often concealed by the clypeus, which is larger in the Lepi- 

 doptera than in all other insects, its size being quite distinctive of the order. The 

 labium or lower lip is small, short, and triangular, and the mentum is nearly obsolete. 

 The labial palpi are fully developed, sometimes rudimentary, and consists of from one 

 to three joints, the terminal being small and pointed. They are renewed in front of 

 the head, on each side of the spiral tongue, and are covered with hairs, their function 

 as touchers or feelers, seeming to be lost. The mandibles are rudimentary, consisting 

 of a pair of horny tubercles, partly concealed by the front edge of the clypeus. The 

 maxilla?, on the other hand, are remarkably developed." The head is also furnished with 

 two organs of smell called the antenna?, with a long tubular tongue for extracting 

 the honey from flowers, which, when at rest, is rolled up in watch-spring form 

 between the palpi ; with a very beautiful and highly specialized pair of complex eyes, 



