202 THE BIOLOGY OF INSECTS 



known theory of sexual selection. The actual pairing of 

 butterflies usually takes place while the insects are in the 

 air, and during the nuptial flight one partner carries the 

 other, whose wings remain closed in the usual resting 

 position, the upper surfaces meeting over the back. Darwin 

 pointed out that, as a rule, the male butterfly carries the 

 female, except in those exceptional cases where the latter 

 sex is the more brightly coloured ; then the female carries 

 the male. This generalisation has been to a great extent 

 confirmed by the extensive obser^^ations on tropical African 

 insects made by G. D. Hale Carpenter (1920). A courting 

 male butterfly often strokes the wings of a desired mate 

 with his fore-feet ; if his attractions prove ineflFectual he 

 flies away and leaves her, if she accepts his advances he 

 carries her off. At least some of the females just mentioned 

 as more brightly coloured than their mates, are more active 

 than they in the courtship, so that examples are aflForded of a 

 complete reversal of the parts commonly played by the two 

 sexes in the drama of pairing. 



Dragon-flies, which vie with butterflies in the brilliance 

 of their colours, comprise many species in which the male 

 displays a brighter or more conspicuous appearance than his 

 mate. Thus in our two common large British '' damsel- 

 flies," Calopteryx virgo and C. splendens^ the wings of the 

 female are uniformly russet or hyaline, while those of the 

 males are respectively suflPused with deep metallic blue, or 

 each traversed by a broad dusky or blue patch. It is likely 

 that such conspicuous distinctions may serve as recognition- 

 marks to the females. In some dragonflies definite acts of 

 courtship have been observed. R. J. Tillyard (191 7) 

 describes how in the small green Australian Hemiphlehia 

 mirahilis^ the abnormally long white terminal ** inferior 

 appendages " of the male *' are displayed as a sign to the 

 female, by raising the abdomen and bending it slightly 

 sideways while walking up the reed stem." The female 

 answers this signal '' by moving the whitened end of her 

 abdomen from side to side in a peculiar manner." After 

 a dance-like flight together the couple mate with one 



