ARTHROPODA 



213 



butterflies the first pair is very rudimentary so that only two 

 pairs are well developed. The adults generally take little food, 

 and the nectar of flowers is their chief food supply; as a rule 

 they live but a short time, although some hibernate and thus live 

 from one season to another. The colors are often very brilliant, 

 and there is frequently considerable sexual dimorphism, the 

 males and females differing from one another in color, size, and 

 shape of wings, and form of antenna". In some butterflies there 

 is a seasonal dimorphism, the imagines or adults which appear 

 in the earl\- summer differing from those which appear in the 

 autumn. 



The butterflies and moths may be distinguished from one 

 another by the structure of the antennae : in the butterflies (Fig. 

 2 14) they are always knobbed or enlarged at the free extremity ; 

 this is never the case with the moths, whose 

 antennas are very variously shaped, sometimes 

 f eathery( Fig. 216), sometimes greatly attenuated ; 

 in the skippers there is a thickening near the 

 extremity of the antennas, but they always 

 terminate in a sharp point. The method of 

 folding the wings when at rest is also different. 

 In butterflies the wings are brought together 

 vertically over the dorsal side of the body ; in 

 moths they may remain extended horizontally, 

 or may be folded flatwise over the abdomen, or 

 be wrapped around the body. 



The larval stage of the Lepidoptera is the 

 caterpillar (Fig. 214); it has three pairs of 

 thoracic legs, and either two pairs or five pairs on the abdomen; 

 the pupa is frequently called a chrysalis (Fig. 214), and is often 

 inclosed in a cocoon (Fig. 215), which the caterpillar forms from 

 the secretion of the two silk glands which open by a common 

 aperture at the mouth. The order is of much economic 

 interest because of the larvae, many of which are most serious 

 pests, not only to the farmer, but to whole communities. Every 

 one is familiar with the clothes moth, whose caterpillar eats 

 woolen garments and furs ; the little moths or millers, as they 

 are often popularly called, are frequently seen flying about 

 rooms in the evening. The larva of a similar moth attacks 



Fig. 215. Cocoon 

 of the silkworm 

 moth, Bombyx 

 mori, about natural 

 size. (After Ship- 

 ley and MacBride.) 



