FAMILY LIFE 201 



while others involve behaviour that suggests selection or 

 choice. 



The recognition by an insect of a possible mate often 

 depends upon the sense of sight. In a previous chapter 

 (p. 90) evidence has been given that butterflies may be 

 attracted v^hen they see a wing of one of their own kind 

 lying on the ground so that they stoop towards it. In 

 most insect families it is the male that seeks the female, as 

 is the case among animals generally, and the distinctive 

 colour-pattern of the wings in such insects as butterflies 

 apparently serves as an attraction when it is recognised. 

 Occasionally the female is attracted by the male ; this is 

 the method of courtship in the Swift Moth Hepialus humuliy 

 a species known as the '* Ghost," because the male's wings 

 are of a sheeny white above while the female's are, like those 

 of both sexes in related species, brownish in hue. In the 

 dusk of the midsummer evenings the white male hovers 

 above the damp pasture or marsh-land ; a female attracted 

 by the white wings collides with him and the two then drop 

 among the herbage and pair. It is of interest to notice that 

 in the most northerly districts of its range, including Shet- 

 land, where at midsummer it is never really dark at night, 

 the male Hepialus humuli is of the same brownish aspect as 

 the female. The obvious conclusion is that the conspicuous 

 white colour of the common British form is a special adapta- 

 tion to aid courtship and hasten pairing ; the male has 

 become modified in correspondence with the special breeding 

 habits of these insects. It is well known that in many 

 butterflies of various families the male is adorned with bright 

 colour while the female is comparatively plain ; several of 

 our British " Blues " (Lycaenidae) and the '* Orange-Tip " 

 {Euchloe cardamines) among the Pieridae afford examples of 

 this. The characteristic blue colours of the male Polyotn- 

 matus tear us, Argiades corydon, and A. bellarguSy respectively, 

 may be regarded as facilitating recognition by their several 

 mates ; but there is no convincing evidence that female 

 butterflies or other insects choose their mates in a '' brilliance 

 competition," as suggested by C. Darwin (1871) in his well- 



