224 THE COLOURATION OF INSECTS 



endeavour is to approach from the flank or rear, and the 

 female, unless willing, turns so as always to face him. 



In the case of Acraeines little time seems to be wasted 

 on persuasion. A male, in the air, makes for the female, 

 who at once falls fluttering to the ground, where the two 

 seem to struggle together. If the female is willing, union 

 is almost immediate ; if not, the male soon flies away. 



On August 2, 1918, in Portuguese East Africa, I saw a 

 very good illustration of this. A fresh specimen of Acraea 

 natalica was flitting aimlessly about, and I was awaiting 

 an opportunity of catching it, when an old and very worn 

 female came by. The male at once went to her, and she 

 fell straight to the ground. I watched for several minutes. 

 The male was very excited, and gripped the female with 

 his legs round the roots of the wings, but she lay motionless 

 on the ground adopting an attitude of passive resistance, 

 the wings folded against her body and pressed closely, 

 so as to prevent the male thrusting his abdomen down to 

 meet hers, which he struggled to do. After a little he 

 managed to pass his abdomen between her wings, but 

 she made no response, and he suddenly gave up and flew 

 away. I caught him, and then found the female still 

 lying motionless on the ground, and secured her too. 



In connection with the pairing of butterflies, the following 

 is of interest to evolutionists. 



During the nuptial flight it is known that in the case 

 of some species the male carries the female, in other cases 

 the positions are reversed, the one that is carried remaining 

 absolutely passive with wings closed. In a discussion on 

 Sexual Selection among insects in the Descent of Man,^ 

 Darwin remarks on some cases where the male is " less 

 bright " than the female, ^ and points out that in the 

 English Pieris, CoUas and Epinephele janira the duller male 

 is supported during the nuptial flight by the female, " so 



^ Chapter xi. 



* The Lycaenid butterfly Lnchnocnema bibulus has a dull brown male 

 which is pursued in courtship by the brighter blue-marked female. 



