Page:Popular Science Monthly Volume 25.djvu/356

344, they could never have grown to their present definite correlation with the nectary, a correlation which, Mr. Darwin says, first convinced him of the reality of their function. "I did not realize the importance of these guiding marks," says Sir John Lubbock, "until, by experiments on bees, I saw how much time they lose if honey which is put out for them is moved even slightly from its usual place." In short, insects, like men, are creatures of habit. How complicated these marks sometimes become, we can see in most orchids.

Again, the attention insects pay to comparatively small details of color and form is clear enough from the mimicry which sometimes occurs among them. In some instances, the mimicry is intended to deceive the eyes of higher animals, such as birds or lizards, and can therefore prove nothing with regard to the senses of the insects themselves. But, in a few cases, the disguise is adopted for the sake of deceiving other insects; and the closeness of the resemblance may be accepted as good evidence of acute vision in the class so mimicked. Thus, several species of flies live as social parasites among the hives or nests of bees. These flies have acquired belts of color and patches of hair, closely imitating the hosts whose honey they steal; while their larvæ have even the ingratitude to devour the larvæ of the bees themselves. Of course, any fly who entered a bee-hive could only escape detection and condign punishment at the hands—or rather at the stings—of its inhabitants, provided it looked so like the householders as to be mistaken by them for one of the community. So any fly which showed at first any resemblance to a bee would for a while be enabled to rob with impunity: but, as time went on, the bees would begin to perceive the true nature of the intruders, and would kill all those which could be readily distinguished. Thus, only the most bee-like flies would finally survive; and the extent to which the mimicry was carried would be a rough test of the perceptive powers of the bees. Now, in these particular cases, the resemblance is so close that it would take in, not only an unpracticed human observer, but even for a moment the entomologist himself. Similar instances occur among Mantidæ and crickets.

And now let us apply these facts to the consideration of the problem before us. If those insects which especially haunt flowers are likely to have so acquired a color-sense and a taste for colors, and if they are capable of observing minute markings, bands, or eye-like spots, then we might naturally infer that they would exhibit a preference for the most beautifully colored and variously ornamented of their own mates. Such a preference, long continued and handed down to after-generations, would finally result in the development of very beautiful and varied colors among the flower-haunting species. We might expect, therefore, to find the most exquisite insects among those races which are most fully adapted to a diet of honey and pollen; and such I believe to be actually the case.