In India flies the most wonderful disappearer of all the butterflies, the Leaf Butterfly. It flies gaily along the sunlight, flashing its beautiful blue, white and black wings, a perfect target for any bird. So a bird dives at it, and it magically vanishes! Where it was there is a dead leaf hanging on the slender branch of a bush or tree. This leaf is so perfectly like other leaves, even fluttering a little in the breeze, with its stem tight against the branch, that you too would look at it again and again and never realize it was a butterfly. The butterfly has simply folded its beautiful wings tightly together and clung onto the branch so that you see only the leaf-like underside.
What hundreds of generations of selection must have produced this butterfly! Some ancestor looked something like a leaf and lived long enough to reproduce because of this protection. Gradually the most leaf-like of its descendants were selected by the inexorable law of the survival of the fittest, until the present leaf butterfly was evolved.
This butterfly dwells in most of the tropics of southern Asia wherever there is sufficient dampness to produce the trees and bushes whose leaves it copies. Always it must fly near these plants, like a boy crossing a field with a bull in it by staying near the fence. When danger comes, a sure way of escape is near.