190 BBITISH BUTTERFLIES 



spot. The under surface, drawn on the same plate (tig. 14), is 

 bluish grey, with a border of orange spots on each hind margin as 

 on the other side. There are also numerous black spots in light 

 rings, the arrangement of which will be seen in the figui-e. 



Some species of butterflies and moths are so variable in their 

 colouring and markings that varieties have often been mistaken for 

 distinct species ; and, in other cases, distinct species are sometimes 

 so similar in character that they are looked upon as identical. 



A butterfly that closelj' resembles the normal Brown Argus in 

 many points, and named Artaxerxes, has often been described as a 

 distinct species, but is now, I believe, recognised by most entomo- 

 logists as a constant variety of the present species. 



It differs from the normal type in having a ivhitc instead of a 

 black spot in the centre of the fore wings, and the border of orange 

 spots is often very indistinct. On the under side, too, instead of 

 black spots in white rings, it has white spots, with little or no trace 

 of a black centre. 



The ordinary Biown Argus is a southerner, and is particularly 

 abundant on the chalk downs of the south coast and the Isle of 

 AVight, but Artaxerxes is to be foiuid only in Scotland and the 

 north of England ; and it is interesting to note that, between these 

 northern and southern districts, intermediate varieties are to be met 

 with. 



Again, AstrarcJte is a double-brooded butterfly, appearing on 

 the wing in May and August ; while Artaxerxes is smgle brooded, 

 flying at midsummer. This fact has lent support to the opinion 

 that the two are distinct species ; but it must be remembered that 

 several insects that are single brooded in one country are double 

 brooded in a warmer climate. 



The caterpillar of Astrarche feeds on the hemlock stork's-bill 

 [Erodium cieutarini)t). It is of a pale yellow colour, with a 

 brownish line on the back ; and is full fed in April and July. 



The Co)nvion Blue {hyccrna learns) 



Although this pretty little butterfly is so common that it is 

 almost sure to be known to all who take any interest in insect life, 

 yet it is important to observe it carefully, since it is an easy matter 

 to confound it with other species of the same genus. 



The upper surfaces of the two sexes are very different, that of 

 the male (Plate VI, fig. 15) being a beautiful lilac blue ; and tliat of 



