ARTIIROPODA. 



303 



From twenty-two thousand to twenty-four thousand 

 Lepidopterous species have been identified. Some of the 

 most common Butterflies are the swallow-tail Papilio, 

 the white Pieris, the sulphur- 

 yellow Colias; the Argynnis, 

 with silver spots on the under 

 side of the hind wings ; the 

 Vanessa, with notched wings. 

 The Sphinges exhibit little 

 variety. They have narrow, 

 powerful wings, and are some- 

 times mistaken for Humming- 

 birds. The " potato -worm" 

 is the caterpillar of a Sphinx. 

 The most conspicuous Moths 

 are the large and beautiful 

 Attacus, distinguished by a ^ 



FIG. 2T6. Head of a Caterpillar, from 



triangular, transparent Spot beneath: a, antennae; b, horny jaws; 



5 , . c, thread of silk from the conical fneu- 



m the Centre OI the Wing; Ins, on either side of which are rudi- 



the white Xombyx, or " silk- mentary palpi " 



worm ;" the reddish-brown Clisiocampa, whose larva, " the 



American Tent-caterpillar," spreads its web in many an 



apple and cherry tree ; the pale, delicate Geometrids ; and 



the small but destructive Tineids, represented by the 



Clothes-moth. 



7. Hymenoptera, comprising at least twenty-five thou- 

 sand species, include the highest, most social, and, we may 

 add (if we except the Silk-worm), the most useful, of In- 

 sects. They have a large, head, with compound eyes and 

 three ocelli, mouth fitted both for biting and lapping, 

 legs formed for locomotion as well as support, and four 

 wings equally transparent, and interlocking by small 

 hooks during flight. The females are usually provided 

 with a sting, or borer. The larvae are footless, helpless 

 grubs, and generally nurtured in cells, or nests. Such are 



