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Show 248 DARWINISM CHAP, feeding-places, those of the two genera Danais and Acrxn. were never among them. The two groups of the great genus Papilio (the true swallowtailed butterflies) which have been already referred to aR having the special characteristics of uneatable insects, have also their imitators in other groups; and thus, the belief in their inedibility-derived mainly from their style of warning coloration and their peculiar habits-is confirmed. In Sont 1t America., several species of the " ..iEneas " group of the. e butterflies are mimicked hy Pieridre and by day-flying moth-; of the genera Castnia and Pericopis. In the East, Papilio hector, P. diphilus, and P. liris, all belonging to the inedible group, are mimicked by the females of other species of Papilio belonging to very distinct groups ; while in Northern India and China, many fine day-flying moth (Epicopeia) have <Wquired the strange forms and peculiar colours of some of the large inedible Papilios of the same regions. In North America, the large and handsome Danai~ archippus, with rich reddish-brown wings, is very common; and it is closely imitated by Limenitis misippus, a butterfly allied to our "white admiral," but which has acquired a colom quite distinct from that of the great bulk of its allies. In the same country there is a still more interesting case. The beautiful dark bronzy green butterfly, Papilio philenor, i~ inedible both in larva and perfect insect, and it is mimicked by the equally dark Limenitis ursula. There is al o in the Southern and 'V estern States a dark female form of the yellow Papilio turnus, which in all probability obtains protection from its general resemblance to P. philenor. Mr. W. H. Edwards has found, by extensive experiment, that both tho dn,rk a,ncl yellow females produce their own kinds, with very few exceptions; and he thinks that the clark form has the ad vantage in the more open regions and in the prairies, 'vhere insectivorous birds abound. But in open country the clark form would be quite as conspicuous as the yellow form, if not more so, so that the resemblance to an inedible species would be there more needed.I The only probable case of mimicry in this country i. that of the moth, Diaphora mendica, whose female only is white, 1 Edwards': Butterflies of No-r·th America, second series, part vi. IX WARNING COLORATION AND MIMICRY 249 while the larva is of protective colours, and therefore almost certainly edible. A much more abundant moth, of about the same , ize and appearing about tho same time, is Spilosoma menthrasti, also white, but in this case both it and its larva, have been proved to be inedible. The white colour of the female Diaphora, although it must be very conspicuous at night, may, therefore, have been acquired in order to resemble the uneatable Spilosoma, and thus gain some protection. 1 Mirnic1·y ctrnong P1·otected (Uneatable) Genem. Before uiving some account of tho numerous other cases of warning colours and of mimicry that oc?Ul' in the animal kinrrclom, it will be well to notice a cunous phenomenon whi~h long puzzled entomologists, but which has at length received a satisfactory explanation. \Ve have hitherto considered, that mimicry could only occur when a comparatively scarce and much persecuted species obtained protection by its close external resemblance to a much more abundant uneatable species inhabiting its own district; and this rule undoubtedly prevails among the great majority of mimicking species all over the world. But Mr. Bates also found a number of pairs of species of different genera of Heliconidre, which resembled each other quite as closely as did the other mimicking species he has described j and since all these insects appear to he equally protected by their inedibility, and to be equally free from persecution, it was n~t easy to see why this curious resen:blance existed, or how. It had been brought about. That it IS not due to close affi.mty is shown by the fact that the resemblance occurs most frequently between the two distinct sub-families into which (as Mr. Bates first pointed out) the Heliconidre are naturally divided on account of very important structural differences. One of these sub-families (the true Heliconime) consists of b~o genera only, Heliconius and Eueicles, the other (the Dana~Hl Heliconime) of no less than sixteen genera; and, in t~e mstances of mimicry we are now discussing, one of the pa1rs or 1 Professor Meldola informs me that he has recorded another case of mimicry among British moths, in which Acidalia subsericata imitates Asth ena candidata. See Ent. J!Io. ~fag., vol. iv. p. 163. |