COURTSHIP AND MATING OF INSECTS 



Courtship ^ 



KG. 



Fig. 1 120. Horizontal Sections through the Heads of a Male (right) and 

 Female (left) Mayfly (Cloe fuscata), enlarged. Br., Brain; fr'.G., ventral gan- 

 glion; G. t Gullet; M,, mouth-parts. 



to normal lateral eyes like those of the females. The reduction 

 of pigment and the presence of a thick layer of homogeneous 

 fluid . . . has led to the conclusion that the special function of 

 these eyes is to discern moving objects in the dusk, to enable 

 the male to secure 

 a mate in the airy 

 twilight dance of 

 the short - lived 

 Mayflies" (fig. 

 1 120). 



In many of the 

 nocturnal Beetles 

 which are known 

 as Glow - Worms 

 the female is wing- 

 less and grub -like, as in our familiar native species (Lampyris 

 noctiluca), and practically monopolizes the power of emitting a 

 clear light from peculiar patches of skin along the sides of the 

 body. As the eyes of the male in such cases are well developed, 

 sometimes remarkably so, the object of the arrangement is 

 tolerably clear. In some of the in- 

 sects of this sort, native to South 

 America, the difference in appearance 

 between the male and female is par- 

 ticularly marked, the latter sex closely 

 resembling the larva (fig. 1121). In 

 Paraguay some of these grub-like fe- 

 males are known as ''railway-beetles", 

 being said to exhibit a " danger sig- 

 nal " at either end, and a row of 

 " caution signals " along each side, or, 

 to speak less metaphorically, possess- 

 ing luminous organs in the positions 

 indicated which respectively emit red 

 and green light. A cynical remark might here be made, as to 

 the appropriateness of such colours in the female sex. 



There is still, however, much to be learnt as to the meaning of 

 luminous organs in insects, for it appears that in species belonging 

 to the same family as the Glow- Worms, e.g. the well-known Fire- 

 Flies (Luciola) of South Europe, the light-giving power is more 



Fig. 1 121. A South American Glow-Worm 

 (Phengodes Hieronymi], X 3. Male on left; 

 female on right 



