BUTTERFLIES AND MOTHS 



325 



with the flight capacity of this butterfly; thus, like other animals 

 endowed with flight, we find that 



(a) It possesses an elongated body. 



(b) All the thoracic somites are united as in the nimble- winged bees 

 (which see, and p. 311). 



(c) The legs are very iveak ; in this way the weight of the body is 

 much lightened, while the limbs are quite sufficient for holding on to 

 objects (motion being effected exclusively by flight). 



3. As the food of the cabbage white is of a liquid nature, its mouth 

 parts (like those of all Lepidoptera) are suctorial. The sucking-tube, 



f.S., The butterfly on the wing (about two-thirds 

 natural size) ; r.S., the butterfly at rest on a twig 

 bearing withered leaves (slightly less than natural 

 size). 



trunk, proboscis, or antlia, consists of 

 the two maxillae, which form two half- 

 tubes, and by the apposition of their edges a complete tube. During 

 rest this trunk is spirally coiled up to protect it from injury (spiral 

 trunk or tongue). The other mouth parts usually found in insects 

 (see p. 314) are quite atrophied, as being of no use to a suctorial insect. 

 Only the labial palpi are distinctly visible. 



Next to the bees (see honey-bee), the butterflies rank as the most 



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