Note 40 — Chapter VII

It was Wallace who first offered an explanation of this interesting case in terms of mimicry. According to this interpretation P. polytes is a palatable form. The larva, which feeds on citronaceous plants, and the chrysalis are both inconspicuous in their natural surroundings. They may be regarded as protectively coloured, and consequently edible and liable to persecution. The original coloration is that of the male and the M female. From this the other two forms of female have diverged in the direction of greater instead of less conspicuousness, although the presumed edibility of the insect might have led us to think that a less conspicuous coloration would have been more to its advantage. But these two females resemble the two species Papilio aristolochiae and Papilio hector, which, though placed in the same genus as P. polytes, belong to a very different section of it[40]. The larvae of these two species are conspicuously coloured black and red with spiny tubercles. They feed upon the poisonous Aristolochia plants. For these reasons and also from the fact that the butterflies themselves are both conspicuous and plentiful it is inferred that they are unpalatable. In short, they are the models upon which the two polytes females that are unlike the male have been built up by natural selection.