THE SWALLOW-TAIL AND THE 'WHITES' 151 



The Clouded Yellow (Colias Edusa) 



Not only are this and the last species similarly named, but a 

 glance at the figures will show that they much resemble each other 

 in appearance ; and we shall also learn presently that in their habits 

 and life history they have much in common. 



The male Edusa is shown on Plate II (fig. 3), and when we 

 compare it with its relative on the opposite side, we are at once struck 

 with the superior richness of the brilliant orange or saffron of the 

 ground colour. The black border of both fore and hind wings is also 

 denser, wider, and more extensive. The whole of the yellow area 

 of the hind wings is dusted more or less with black scales, with the 

 exception of a round central spot of deep orange, corresponding with 

 the orange spots on the hind wings of Hyale. 



The female, which is shown in the accompanying woodcut, is 

 generally larger than the male, and is further distinguished by the 

 very pale yellow spots 

 that break the black 

 border of both pairs of 

 wing?. 



Edusa further resem- 

 bles Hyale in the reddish 

 colour of the antenna ; 

 and, in both the species, 

 the red legs form a 

 pleasing contrast with the 

 yellow furry surface of the FIG. 66. THE CLOUDED YELLOWFEMALE. 

 under side of the thorax. 



There is a variety of the female of this butterfly, in which the 

 ground colour is a very pale yellow, almost white. The hind wings 

 are more thickly dusted with black scales than in the normal insect, 

 and the orange spots of these wings show up much more conspicu- 

 ously from the contrast with their surroundings. 



It is usual to apply distinct names to constant varieties of species 

 names that are to be added to the ordinary title. In this particu- 

 lar case the distinguishing name is Helice, so that we should speak 

 of the variety of Edusa above mentioned as : 



Colias Edusa, var. Helice 



Like Hyale, Edusa is particularly capricious in its appearance. 

 In certain summers it absolutely swarms in favourite localities, 



