Butterflies generally hold their wings erect when they are at rest, with their 

 upper surfaces facing each other, and only the under surfaces displaying their 

 colors to the eye. In the genus Ageronia the insect prefers, like some moths, to 

 settle upon the bark of trees, with the wings spread flat, and the head pointing 

 downward. Many of the Hesperiidce, or "Skippers," have the habit when they 

 are at rest of holding the fore wings folded together, while the hind wings are ex- 

 panded horizontally. Many of the butterflies known as "Hair-streaks," belonging 

 to the genus Thecla and its allies, have the curious habit, when at rest upon the end 

 of a twig or leaf, of moving their folded wings backward and forward, first on one 

 side and then on the other, thus partially displaying with each movement the splen- 

 did blue surfaces of the upper side of the wings. 



The abdomen of butterflies consists normally of nine segments (see Plate A, 

 Fig. c). In most butterflies except the Ithomiids, the end of the abdomen does not 

 extend beyond the anal angle of the hind wings. In the moths, on the other hand, 

 there are multitudes of genera in which the extremity of the abdomen extends far 

 beyond the hind margin of the posterior wings. This is particularly true of the 

 hawk-moths. A minute examination of the abdomen of a butterfly reveals in 

 each segment except the last a little valve-like orifice on either side. These openings 

 are known as spiracles (see Plate A, Fig. c). Through these the insect breathes. 

 Insects do not breathe through their mouths, like vertebrates, and their lungs, or 



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