MOTHS AND BUTTERFLIES. 471 



probably used as a means of defence against parasitic and other enemies* The head 

 of the Lycenid larvae is also retractile into the folds of the second segment, so that it 

 is hardly visible from above ; while Mr. W. H. Edwards has observed that they are 

 furnished with retractile spines giving out a honey-like fluid, especially grateful to 

 certain species of ants. The Papilionidae have the head also partially concealed ; but 

 in the Nymphalidae and other groups it is at all times free and extended. In the 

 Hesperidse the second segment is usually greatly constricted, giving the head an 

 almost monstrous appearance. In most cases the caterpillars of the butterflies move 

 rapidly from place to place ; but in the Lycenids they are oniscifdrm, or shaped some- 

 what like the common wood-louse, the pro- 

 legs being hardly visible, and the animal .v'rt3piFl™?^^^i'^^ 

 seeming to glide rather than walk over the -^^^^\ \ \ \ \ \ ,\ \ T 'P^^^^2?«s?===:r-^-- 

 surface of its ■ resting-place. The forms '^^^^^'^'^^'''^siiaiJij;^^^ 

 and armature of the larvae are very varia- fig. 595. -Larva of iz/rana. 

 ble, their bodies being in some cases almost 



naked, and in others covered with hard and complicated spines, or with corrugations, 

 foveas, or tubercles of an almost endless variety of pattern. No special law can be 

 laid down for the duration of the larval stage ; but from fifteen to thirty days may be 

 regarded as the usual period, though many species remain longer than this, and not a 

 few pass over the winter in their caterpillar condition. 



To the stage succeeding the larva, the various terms aurelia, pupa, and chrysalis 

 have been applied, the last being that now generally used by lepidopterists as applied 

 to the Diurnals, the word pupa being given to the corresponding state in the moths, 

 or those insects which spin cocoons. The name aurelia has now become obsolete, and 

 was never more than of partial application, having been used by the older naturalists 

 from the fact that many of the chrysalides of butterflies are marked with golden spots 

 and blotches (aurum, gold) giving rise to the term. 



The chrysalis, properly so called, may be said to consist of a series of more or less 

 ^^_ horny and variously-formed integuments, covering up and concealing 

 the future external organs of the perfect insect. In the group we are 

 discussing, there is a tendency towards a general outline as regards the 

 form, which is longer than broad, thickest a little above the middle, 

 and tapering somewhat abruptly to the posterior extremity. Some 

 chrysalides are smooth and rounded, without angles ; others are armed 

 with long and sharp spines ; others bear large thoracic or abdominal 

 protuberances, while some are so grotesque in appearance as to be inde- 

 scribable in familiar words. The position of rest while underffoinsr the 



Fig. 596.-Clirys- , , . ,. . . ' . . .,,,*. ® 



alls of Danais change to the imago condition is a question 01 considerable interest, 

 having a most important bearing upon the classification of the families, 

 one group suspending themselves by the tail, and another by a girth around the body. 

 The late Dr. Boisduval very happily distinguished these as the Suspensi and the Suc- 

 cincti. To the former belong the great group of the Nymphalidae (which is by far the 

 most numerous over the world in point of individuals, if not of species), and to the 

 latter the swallow-tailed butterflies, the garden whites, and the common yellow species 

 {Colias). In the Succincti the head is usually directed upwards, while the Lycaenidse 

 generally fasten themselves longitudinally upon the leaf or stem of a plant, and the 

 Hesperidae fold themselves up in a leaf, with silken bands around the body, thus show- 

 ing their close relationship to the moths. A great deal of discussion has arisen among 



