BUTTERFLIES AND MOTHS. 321 



form differ from each other in color, and the sexes of the imitat- 

 ing form differ in a like manner. Several cases have also been 

 recorded where the females alone imitate brilliantly-colored and 

 protected species, the males retaining "the normal aspect of their 

 "immediate congeners." It is here obvious that the successive 

 variations by which the female has been modified have been 

 transmitted to her alone. It is, however, probable that some 

 of the many successive variations would have been transmitted 

 to, and developed in, the males had not such males been elim- 

 inated by being thus rendered less attractive to the females; so 

 that only those variations were preserved which were from the 

 first strictly limited in their transmission to the female sex. We 

 have a partial illustration of these remarks in a statement by Mr. 

 Belt;*^ that the males of some of the Leptalides, which imitate 

 protected species, still retain in a concealed manner some of 

 their original characters. Thus in the males "the upper half of 

 "the lower wing is of pure white, whilst all the rest of the wings 

 "is barred and spotted with black, red and yellow, like the 

 "species they mimic. The females have not this white patch, and 

 "the males usually conceal it by covering it with the upper wing, 

 "so that I cannot imagine its being of any other use to them 

 "than as an attraction in courtship, when they exhibit it to the 

 "females, and thus gratify their deep-seated preference for the 

 "normal color of the Order to which the Leptalides belong." 



Bright Colors of Caterpillars. — Whilst reflecting on the beauty 

 of many butterflies, it occurred to me that some caterpillars were 

 splendidly colored; and as sexual selection could not possibly 

 have here acted, it appeared rash to attribute the beauty of the 

 mature insect to this agency, unless the bright colors of their 

 larva could be somehow explained. In the first place, it may be 

 observed that the colors of caterpillars do not stand in any close 

 correlation with those of the mature insect. Secondly, their 

 bright colors do not serve in any ordinary manner as a protection. 

 Mr. Bates informs me, as an instance of this, that the most con- 

 spicuous caterpillar which he ever beheld (that of a Sphinx) lived 

 on the large green leaves of a tree on the open llanos of South 

 America; it was about four inches in length, transversely banded 

 with black and yellow, and with its head, legs, and tail of a 

 bright red. Hence it caught the eye of any one who passed by, 

 even at a distance of many yards, and no doubt that of every 

 passing bird. 



I then applied to Mr. Wallace, who has an innate genius for 

 solving difficulties. After some consideration he replied: "Most 

 "caterpillars require protection, as may be inferred from some 



22 'The Naturalist in Nicaragua,' 1874, p. 385. 

 22 



