INSECTS. 353 



females of the same species inhabit the same district, feed 

 on t;he same food and follow exactly the same habits of 

 life. Even when the sexes resemble each other we can 

 hardly believe that their brilliant and beautifully arranged 

 colors are the purposeless result of the nature of the tissues 

 and of the action of the surrounding conditions. 



With animals of all kinds, whenever color has been 

 modified for some special purpose, this has been, as far as 

 'we can judge, either for direct or indirect protection, or as 

 an attraction between the sexes. With many species of 

 butterflies the upper surfaces of the wings are obscure; and 

 this in all probability leads to their escaping observation 

 and danger. But butterflies would be particularly liable 

 to be attacked by their enemies when at rest; and most 

 kinds while resting raise their wings vertically over their 

 backs, so that the lower surface alone is exposed to view. 

 Hence it is this side which is often colored so as to imitate 

 the objects on which these insects commonly rest. Dr. 

 Rossler, I believe, first noticed the similarity of the closed 

 wings of certain Vanessae and other butterflies to the bark 

 of trees. Many analogous and striking facts could be given. 

 The most interesting one is that recorded by Mr. Wallace* 

 of a common Indian and Sumatran butterfly (Kallima), 

 which disappeai-s like magic when it settles on a bush; for 

 it hides its head and antennae between its closed wings, 

 which, in form, color and veining, cannot be distinguished 

 from a withered leaf with its footstalk. In some other 

 cases the lower surfaces of the wings are brilliantly colored, 

 and yet are protective; thus in Thecla rubi the wings when 

 closed are of an emerald green and resemble the young 

 leaves of the bramble, on which in spring this butterfly 

 may often be seen seated. It is also remarkable that in very 

 many species in which the sexes differ greatly in color on 

 their upper surface, the lower surface is closely similar or 

 identical in both sexes, and serves as a protection, f 



Although the obscure tints both of the upper and under 

 sides of many butterflies no doubt serve to conceal them, yet 

 we cannot extend this view to the brilliant and conspicuous 

 colors on the upper surface of such species as our admiral and 



* See the interesting article in the " Westminster Review," July, 

 1867, p. 10. A wood-cut of the Kallima is given by Mr. Wallace in 

 " Hardwicke's Science Gossip," Sept., 1867, p. 196. 



f Mr. G. Fraser, in "Nature," April, 1871, p. 489. 



