72 



SCIENCE-GOSSIP. 



anterior segments that correspond to the thorax of 

 the perfect insect are each furnished with a 

 pair of legs, three-jointed and clawed. These are 

 called " true legs." Besides these, on the posterior 

 segments, are several pairs of fleshy legs called 

 pro-legs, and a pair of claspers on the last segment. 



The chief function performed by the larva is feeding, 

 and growth is very rapid. Consequent upon this 

 is a periodical moulting or change of integument, until 

 the pupa stage is reached. 



The larvae of the different families of butterflies are 

 variously shaped. Some are cylindrical as in the 

 Papilionidae, Pieridae, Nymphalidae and Danaidae. 

 Others are onisciform or woodlouse-shaped, as in 

 Erycinidae and Lycaenidae, limaciform or slug- 

 shaped, as in Apaluridae, pisciform in Satyridae, 

 and fuciform as in Hesperidae. 



On the surface they are mostly but not always 

 smooth in Papilionidae, Pieridae, Danaidae, Satyridae, 

 and Hesperidae. In Nymphalidae they are generally 

 spiny or furnished with tubercular projections. 



Many of the larvae of Papilionidae have retractile 



condition of growth being suspended. Movement is- 

 very limited, entirely segmental, and never loco- 

 motive ; the legs being concealed beneath the 

 integument. During the pupa stage the various 

 parts of the imago or perfect insect are undergoing 

 development. Towards the end of this condition the 

 markings and even coloration of the wings of the 

 butterfly, may often be traced through the wings 

 cases, which occupy the lateral regions of the thorax. 

 The pupa sometimes assumes an upright position, 

 being affixed to the stem of a plant or other object by 

 girths of silk. Others are attached by the posterior 

 abdominal segment, and therefore hang head down- 

 wards. Some again are encased in a slight cocoon 

 of silk, somewhat after the manner of moths. Guenee 

 divided the butterflies into three divisions in accord- 

 ance with these various methods of pupation, and in 

 my former work on the Butterflies of Europe I have 

 adopted his method, which is as follows : — 



I. SucciNCTl. — Pupa upright with a thoracic 

 girth. Papilionidae, Pieridae, Lycaenidae, and' 

 Erycinidae. 



Fig. I. 



Fi&.l. 



Fig. 3. 



FiG.-^. 



Vaniissa urticat'. — Stages in Transformation from Larva to Pupa. 



horn-like processes attached to the head as in Papilio 

 nmchaon and P. podaliritis, Painassiiis apollo, etc. 

 In the Apaturidae there are somewhat similar 

 appendages, which however are not retractile like 

 those of the former family. In Danais there are 

 three pairs of filiform appendages, two anterior and 

 one on the posterior segment. The colours of the 

 larvae of butterflies are probably protective. Thej' 

 aire mostly green, brown or black, in various shades. 

 No palaearctic butterfly larvae that are known, are 

 distinctly hairy, as is the case in many moths. 



In their habits they are sometimes gregarious, 

 notably so in the case of Ap07'ia crataegi, where they 

 live under the protection of a common web. Some 

 of the comifton Vanessae, such as V. to and V. 

 jirticac, furnish familiar examples of gregarious 

 larvae. Often they are solitary. This difference in 

 habit depends on whether the eggs are laid singly or 

 in groups. 



Chrysalis. 



The third stage is that of the pupa or nymph, 

 ushered in by the last change of the larval integu- 

 ments. It is in butterflies always a stage of almost 

 complete quiescence, the function of feeding and the 



II. Susi'ENSi. — Pupa suspended. Libytheidae,. 

 Apaturidae, Nymphalidae, Danaidae, Satyridae. 



III. Involuti. — Pupa enclosed in a slight cocoon. 

 Hesperidae. 



Some of the Satyridae form an exception in group II.,. 

 burying themselves at the roots of plants. Thais,, 

 Pai-nassius, and Zeg/is, are also peculiar in their 

 pupation. 



In shape the pupae are sometimes smooth and 

 sometimes angulated in outline, more commonly the 

 latter, especially in Pieridae and Nymphalidae. In 

 Danaidae, they have a peculiar appearance of antero- 

 posterior flattening. The colour of the pupae of 

 butterflies is probably for the most part protective, 

 being generally either grey, green, or brown, some- 

 times they are speckled, as in many Pieridae. 

 Occasionally the eggs are decorated with beautiful, 

 metallic golden markings, as in Vanessa, Argynnis, 

 Danais, etc. • It was this peculiarity which a century 

 ago obtained for them the name of "aurelia," and, 

 consequently, collectors of butterflies were called 

 "aurelians." Hence also the word "chrysalis," 

 so commonly applied to the pupa state of a lepidop- 

 terous insect. 



