410 THE DESCENT OF MAN 



that ia the Brazilian forests and Malayan islands, many 

 common and highly decorated butterflies are weak flyers, 

 though furnished with a broad expanse of wing; and they 

 "are often captured with pierced and broken wings, as if 

 they had been seized by birds, from which they had 

 escaped ; if the wings had been much smaller in proportion 

 to the body, it seems probable that the insect would more 

 frequently have been struck or pierced in a vital part, and 

 thus the increased expanse of the wings may have been 

 indirectly beneficial." 



Display. — The bright colors of many butterflies and of 

 some moths are specially arranged for display, so that they 

 may be readily seen. During the night colors are not 

 visible, and there can be no doubt that the nocturnal 

 moths, taken as a body, are much less gayly decorated than 

 butterflies, all of which are diurnal in their habits. But 

 the moths of certain families, such as the Zygaenidae, several 

 Sphingidae, Uraniidae, some Arctiidae and Saturniidse, fly 

 about during the- day or early evening, and many of these 

 are extremely beautiful, being far brighter colored than 

 the strictly nocturnal kinds. A few exceptional cases, 

 however, of bright-colored nocturnal species have been 

 recorded." 



There is evidence of another kind in regard to display. 

 Butterflies, as before remarked, elevate their wings when 

 at rest, but while basking in the sunshine often alternately 

 raise and depress them, thus exposing both surfaces to full 

 view; and although the lower surface is often colored 

 in an obscure manner as a protection, yet in many species 

 it is as highly decorated as the upper surface, and sometimes 

 in a very different manner. In some tropical species the 

 lower surface is even more brilliantly colored than the 

 upper.'^ In the English fritillaries {Argynnis) the lower 



•* For instance, Litliosia; but Prof. Westwood ("Modern Class, of Insects," 

 vol. ii. p. 390) seems surprised at this case. On the relative colors of diurnal 

 and nocturnal Lepidoptera, see ibid., pp. 333 and 392; also Harris, "Treatise 

 en the Insects of New England," 1842, p. 815. 



" Such differences between the upper and lower surfaces oi the wings of 



