356 THE DESCENT OF MAN. 



lace,* namel}^ that in 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 vis- 

 ible, and there can be no doubt that the nocturnal moths, 

 taken as a body, are much less gayly decorated than butter- 

 flies, all of which are diurnal in their habits. But the 

 moths of certain families, such as the Zyggenid^e, several 

 Sphingidae, Uraniidse, some Arctiidae and Saturniidae, 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, how- 

 ever, of bright - colored nocturnal species have been 

 recorded, f 



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 maimer 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. J; 

 In the English fritillaries {Argynnis) the lower surface 



*" Westminster Review," July, 1867, p. 16. 



f For instance, Lithosia; but Prof. Westwood ("Modern Class, of 

 Insects," vol. ii, p. 890) seems surprised at this case. On the relative 

 colors of diurnal and nocturnal Lepidoptera, see ibid., pp. 333, 392; 

 also Harris, " Treatise on the Insects of New England," 1842, p. 315. 



\ Such differences between the upper and lower surfaces of the 

 wings of several species of Papiliomay be seen in the beautiful plates 

 to Mr. Wallace's "Memoir on the Papilionidse of the Malayan 

 Region," in "Transact. Linn. Soc," vol. xxv, part i, 1865. 



