GENERATION OF INSECTS. 



431 



160 



Sphinx Ligastri. Imago. 



pair upon the anal segment. The prolegs, which entirely disappear 

 in the pupa, are, however, less constant than the thoracic legs. The 

 larvje of the Lepidoptera are commonly herbivorous, and devour 

 considerable quantities of vegetable matter. The coarsely masticated 

 leaves are conveyed, by a short and wide oesophagus (d), to a much 

 longer and wider chylific stomach (A.) Six pairs of capillary malpi- 

 ghian tubes indicate, by their insertion, the commencement of the 

 intestine (m), which terminates by a wide, short, and longitudinally 

 plicated rectum, upon the last segment (n). 



In its perfect state, the butterfly, or sphinx, subsists only on the 

 fluids of vegetables : its maxiUary apparatus is converted, by the 

 abrogation of the homy mandibles and the extreme prolongation of 

 the maxillae, into a long suctorial tube, called " antlia" (Jtg. 160, »). 

 A long and slender oeso- 

 phagus (J) conveys the 

 fluids to the chylific sto- 

 mach, and to a wide crop, 

 which during the pupa 

 state has been gradually 

 expanded from one side of 

 the end of the gullet. The 

 chylific stomach (A) has shrunk into a comparatively short fusiform 

 cavity, which is still characterized by the transverse sacculi and 

 constrictions. The small intestine (/) has diminished in width, but 

 increased in length, and now lies in several convolutions between 

 the chylific stomach and colon, the upper part of which has also been 

 produced into a CJecum. (m) The malpighian vessels are diminished 

 in length, but still communicate, by a short common duct on each 

 side, with the commencement of the small intestine. 



In the bee the metamorphosis of the digestive organs is still more 

 striking than in the butterfly, inasmuch as the alimentary cavity con- 

 sists, beyond the short and wide oesophagus, exclusively of a large 

 transversely plicated chylific stomach without intestine or vent. 

 The larvae of the parasitic Hymenoptera are in the same condition, 

 so that the fluids of the insect they may infest are not contaminated 

 by the faeces of the parasite. The larvae of bees and wasps have 

 from four to six malpighian vessels, which shrink in diameter and 

 contract in length during the pupa state. 



The gizzard is never present in the vermiform larvae of the 

 Coleoptera, although usually possessed by the perfect insect. In 

 those of the Scarabcei, Melolonthce, and most herbivorous Coleop- 

 tera, the chylific stomach is shorter than in the imago ; but it is 

 furnished at both ends with csecal appendages, which disappear 



