328 THE DESCENT OF MAN. 



ous colors may be of use to these insects by giving notice 

 that they are unpalatable. Thus it has been observed* that 

 a bright-colored Indian locust was inyariably rejected when 

 offered to birds and lizards. Some cases, however, are 

 known of sexual differences in color in this order. The 

 male of an American cricket \ is described as being as 

 white as ivory, while the female varies from almost white to 

 greenish-yellow or dusky. Mr. Walsh informs me that the 

 adult male of Spectrum femoratum (one of the Phasmidae) 

 " is of a shining brownish-yellow color; the adult female 

 being of a dull, opaque, cinereous brown; the young of 

 both sexes being green/' Lastly, I may mention that the 

 male of one curious kind of cricket J is furnished with " a 

 long membranous appendage, which falls over the face like 

 a veil;" but what its use may be is not known. 



Neuroptera. Little need here be said, except as to color. 

 In the Ephemeridae the sexes often differ slightly in their 

 obscure tints ; but it is not probable that the males are 

 thus rendered attractive to the females. The Libellulidae 

 or dragon-flies are ornamented with splendid green, blue, 

 yellow, and vermilion metallic tints; and the sexes often 

 differ. Thus, as Prof. "Westwood remarks,! the niales 

 of some of the Agrionidae, " are of a rich blue with black 

 wings, while the females are fine green with colorless 

 wings." But in Agrion Ramburii these colors are exactly 

 reversed in the two sexes. 1" In the extensive North Ameri- 

 can genus of Hetaerina, the males alone have a beautiful 

 carmine spot at the base of each wing. In Anax junius 

 the basal part of the abdomen in the male is a vivid ultra- 

 marine blue, and in the female grass-green. In the allied 

 genus Gomphus, on the other hand, and in some other 

 genera, the sexes differ but little in color. In closely-allied 



*Mr. Cli. Home, in "Proc. Ent. Soc.," May 3, 1869, p. 12. 



f The (Ecanthus nivalis. Harris, " Insects of New England," 1842, 



E. 124. The two sexes of the OS. pellucidus of Europe differ, as I 

 ear from Victor Carus, in nearly the same manner. 

 J Platyblenmus; Westwood, "Modern Class.," vol. i, p. 447. 

 B. D. Walsh, the " Pseudoneuroptera of Illinois," in " Proc. Ent. 

 Soc. of Philadelphia," 1862, p. 361. 

 |j " Modern Class.," vol. ii, p. 37. 



1 Walsh, ibid., p. 381. I am indebted to this naturalist for the fol- 

 lowing facts on Heta3rina, Anax and Gomphus. 



