The other day, when I was watching that little red-spotted butterfly whose psychology I found so interesting, I hardly took enough account, perhaps, of the insect’s own subjective feelings of pleasure and pain. The first great point to understand about these minute creatures is that they are, after all, mainly pieces of automatic mechanism: the second great point is to understand that they are probably something more than that as well. To-day I have found another exactly similar butterfly, and I am going to work out with myself the other half of the problem about him. Granted that the insect is, viewed intellectually, a cunning bit of nervous machinery, may it not be true at the same time that he is, viewed emotionally, a faint copy of ourselves?
Here he stands on a purple thistle again, true, as usual, to the plant on which I last found him. There can be no doubt that he distinguishes one colour from another, for you can artificially attract him by putting a piece of purple paper on a green leaf, just as the flower naturally attracts him with its native hue. Numerous observations and experiments have proved with all but absolute certainty that his discrimination of colour is essentially identical with our own; and I think, if we run our eye up and down nature, observing how universally all animals are attracted by pure and bright colours, we can hardly doubt that he appreciates and admires colour as well as discriminates it. Mr. Darwin certainly judges that butterflies can show an æsthetic preference of the sort, for he sets down their own lovely hues to the constant sexual selection of the handsomest mates. We must not, however, take too human a measure of their capacities in this respect. It is sufficient to believe that the insect derives some direct enjoyment from the stimulation of pure colour, and is hereditarily attracted by it wherever it may show itself. This pleasure draws it on, on the one hand, towards the gay flowers which form its natural food; and, on the other hand, towards its own brilliant mates. Imprinted on its nervous system is a certain blank form answering to its own specific type; and when the object corresponding to this blank form occurs in its neighbourhood, the insect blindly obeys its hereditary instinct. But out of two or three such possible mates it naturally selects that which is most brightly spotted, and in other ways most perfectly fulfils the specific ideal. We need not suppose that the insect is conscious of making a selection or of the reasons which guide it in its choice: it is enough to believe that it follows the strongest stimulus, just as the child picks out the biggest and reddest apple from a row of ten. Yet such unconscious selections, made from time to time in generation after generation, have sufficed to produce at last all the beautiful spots and metallic eyelets of our loveliest English or tropical butterflies. Insects always accustomed to exercising their colour-sense upon flowers and mates, may easily acquire a high standard of taste in that direction, while still remaining comparatively in a low stage as regards their intellectual condition. But the fact I wish especially to emphasise is this — that the flowers produced by the colour-sense of butterflies and their allies are just those objects which we ourselves consider most lovely in nature; and that the marks and shades upon their own wings, produced by the long selective action of their mates, are just the things which we ourselves consider most beautiful in the animal world. In this respect, then, there seems to be a close community of taste and feeling between the butterfly and ourselves.
Let me note, too, just in passing, that while the upper half of the butterfly’s wing is generally beautiful in colour, so as to attract his fastidious mate, the under half, displayed while he is at rest, is almost always dull, and often resembles the plant upon which he habitually alights. The first set of colours is obviously due to sexual selection, and has for its object the making of an effective courtship; but the second set is obviously due to natural selection, and has been produced by the fact that all those insects whose bright colours show through too vividly when they are at rest fall a prey to birds or other enemies, leaving only the best protected to continue the life of the species.
But sight is not the only important sense to the butterfly. He is largely moved and guided by smell as well. Both bees and butterflies seem largely to select the flowers they visit by means of smell, though colour also aids them greatly. When we remember that in ants scent alone does duty instead of eyes, ears, or any other sense, it would hardly be possible to doubt that other allied insects possessed the same faculty in a high degree; and, as Dr. Bastian says, there seems good reason for believing that all the higher insects are guided almost as much by smell as by sight. Now it is noteworthy that most of those flowers which lay themselves out to attract bees and butterflies are not only coloured but sweetly scented; and it is to this cause that we owe the perfumes of the rose, the lily-of-the-valley, the heliotrope, the jasmine, the violet, and the stephanotis. Night-flowering plants, which depend entirely for their fertilisation upon moths, are almost always white, and have usually very powerful perfumes. Is it not a striking fact that these various scents are exactly those which human beings most admire, and which they artificially extract for essences? Here, again, we see that the æsthetic tastes of butterflies and men decidedly agree; and that the thyme or lavender whose perfume pleases the bee is the very thing which we ourselves choose to sweeten our rooms.
Finally, if we look at the sense of taste, we find an equally curious agreement between men and insects; for the honey which is stored by the flower for the bee, and by the bee for its own use, is stolen and eaten up by man instead. Hence, when I consider the general continuity of nervous structure throughout the whole animal race, and the exact similarity of the stimulus in each instance, I can hardly doubt that the butterfly really enjoys life somewhat as we enjoy it, though far less vividly. I cannot but think that he finds honey sweet, and perfumes pleasant, and colour attractive; that he feels a lightsome gladness as he flits in the sunshine from flower to flower, and that he knows a faint thrill of pleasure at the sight of his chosen mate. Still more is this belief forced upon me when I recollect that, so far as I can judge, throughout the whole animal world, save only in a few aberrant types, sugar is sweet to taste, and thyme to smell, and song to hear, and sunshine to bask in. Therefore, on the whole, while I admit that the butterfly is mainly an animated puppet, I must qualify my opinion by adding that it is a puppet which, after its vague little fashion, thinks and feels very much as we do.