Page:Popular Science Monthly Volume 53.djvu/684

664 well as of the rest of the exposed portions of the body, are such as to assimilate closely with the bark of the tree upon which the insect rests. In such a situation it requires a sharp eye to detect the presence of the moth, which, unless disturbed, flies only at night, remaining all day exposed to the attacks of many enemies. Probably



the most important of these are the birds, especially species like the woodpeckers, which are constantly exploring all portions of the trunks of trees.

The chief beauty of these Catocalas as they are seen spread out in the museum cabinet lies in the fact that the hind wings, which, when the moth is at rest in life, are concealed by the front ones, are brightly colored in contrasting hues of black, red, and white in various brilliant combinations. These colors, in connection with the soft and blended tones of the front wings, make a very handsome insect.

To explain these colors many suggestions have been made. The protective hues of the upper wings are easy to account for by accepted biological theories, but the bright colors of the under wings have presented more difficulties. Some biologists have supposed that the latter were without special significance, being produced by the tendencies of the insect to bright colors—the tendency not being kept down by the eliminating factors which would operate in the case of exposed portions of the body. On this principle Mr. Beddard would "expect that bright coloration would be the rule rather than the exception among nocturnal insects, for, however bright and varied, the colors would be invisible at night and could do their