In regard to butterflies, the males and females are both often equally brilliantly colored; in other species the differences in the sexes are very striking. Darwin states:— “Even within the same genus we often find species presenting extraordinary differences between the sexes, whilst others have their sexes closely alike.” The fine colors of the wings of many moths are also supposed by Darwin to have arisen through sexual selection, although the colors are usually on the lower wings, which are covered during the day by the less ornamented upper wings. It is assumed that, since the moths often begin to fly at dusk, their colors might at this time be seen and appreciated by the other sex. It should not be overlooked, however, that, in the case of some of the most highly colored moths, it is known that the males find the females through the sense of smell. Moreover, although moths are often finely colored, Darwin points out that “it is a singular fact that no British moths which are brilliantly colored, and, as far as I can discover, hardly any foreign species, differ much in color according to sex; though this is the case with many brilliant butterflies.” Yet Darwin does not hesitate to conclude: “From the several foregoing facts it is impossible to admit that the brilliant colors of butterflies, and of some few moths, have commonly been acquired for the sake of protection. We have seen that their colors and elegant patterns are arranged and exhibited as if for display. Hence I am led to believe that the females prefer or are most excited by the more brilliant males; for on any other supposition the males would, as far as we can see, be ornamented to no purpose. We know that ants and certain lamellicorn beetles are capable of feeling an attachment for each other, and that ants recognize their fellows after an interval of several months. Hence there is no abstract improbability in the Lepidoptera, which probably stand nearly or quite as high in the scale as these insects, having sufficient mental capacity to admire bright colors. They certainly discover flowers by color.” So far as the evidence of ants having an attachment for each other is concerned, we may eliminate this part of the argument, since the evidence on which the statement is based is now regarded as only showing that ants recognize each other by their sense of smell, which resides in the antennæ. Hence the so-called fondling means only that the ants are trying by smell to determine the odor of the other individual.