SEXUAL SELECTION 51 



teetering gait, the bright-colored portions of the body being 

 displayed to the most advantage. It behooves him to be 

 discreet in his courtship, for, if he fails to charm the 

 female, he is likely to be seized and devoured by her. Dr. 

 and Mrs. Peckham, of Milwaukee, who have been the most 

 careful observers of the hunting spiders, the group of 

 spiders in which courting colors and courting habits are 

 perhaps most developed, are fully convinced that the 

 female is influenced by the display of his charms made 

 by the male, and that his success is often determined by 

 this stimulus. 



Among insects are found many instances of structures 

 present in the males and wanting in the females of the 

 same species. Stridulating organs for the production of 

 sounds are common among the grasshoppers, crickets, and 

 cicadas (Plate 29, A). The males of many beetles have 

 enlarged jaws of a form not useful for fighting (Plate 29, B), 

 or hornlike appendages on the head or thorax, which are 

 not seen in the females (Plate 30; Fig. 7). In many species 

 of butterflies the males are decidedly more brilliant than 

 the females (Plate 84). Bates, speaking of the butterflies 

 on the upper Amazon, says: "They were of almost all 

 colors, sizes, and shapes. I noticed here altogether eighty 

 species, belonging to twenty-two different genera. It is a 

 singular fact that, with a few exceptions, all the individuals 

 of the various species thus sporting in sunny places were 

 of the male sex; their partners, which are much more 

 soberly dressed and immensely less numerous than the 

 males, being confined to the shades of the woods." 1 (Italics 

 mine.) Again, speaking of the butterflies of the whole 



1 The Naturalist on the River Amazon. 



