THE BUTTERFLIES AND MOTHS 



53 



from one end of the cocoons by cutting the silk with a pair of 

 stout spines, one on each side of the thorax, at the base of 

 the anterior wings. 



Underwings. A very striking group of moths is the under- 

 wings (Catoc'ala, Fig. 32), which have the anterior wings in 

 sober tints of brown 

 or gray, but the pos- 

 terior wings black 

 with broad mark- 

 ings of red or yel- 

 low. When at rest, 

 as shown in the 

 figure, the posterior 

 wings are covered 

 and the moth tends 

 to be protectively 

 colored ; but when 

 in flight the broad, 

 contrasting colors 

 are conspicuous. It 

 is usual to account 

 for the coloration of 

 the anterior wings 

 by the principle of 



protective resem- FIG. 32. Underwing at Rest. Reduced 



blance. Some nat- 

 uralists have thought that the bright colors of the posterior 

 wings demand no other explanation than that they have 

 resulted from a natural tendency to bright colors ; while 

 others have suggested that they serve to call attention to a 

 non-vital part. 



Hawk-Moths. The hawk-moths or sphinx-moths (Fig. 33) 

 are easily recognized by the stout conical body, long coiled 

 proboscis, narrow pointed wings, and the slender antennae. 



> 



f 



