ix WAKNTNTG COLORATION AXD MIMICRY 249 



while the larva is of protective colours, and therefore almost 

 certainly edible. A much more abundant moth, of about the 

 same size and appearing about the 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 re- 

 semble the uneatable Spilosoma, and thus gain some pro- 

 tection. 1 



Mimicry among Protected ( Uneatable) Genera. 



Before giving some account of the numerous other cases 

 of warning colours and of mimicry that occur in the animal 

 kingdom, it will be well to notice a curious phenomenon 

 which long puzzled entomologists, but which has at length 

 received a satisfactory explanation. 



We 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 dis- 

 trict; 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 Heliconida?, which resembled each other quite as closely as 

 did the other mimicking species he has described \ and since 

 all these insects appear to be equally protected by their in- 

 edibility, and to be equally free from persecution, it was not 

 easy to see why this curious resemblance existed, or how it 

 had been brought about. That it is not due to close affinity 

 is shown by the fact that the resemblance occurs most fre- 

 quently between the two distinct sub-families into which (as 

 Mr. Bates first pointed out) the Heliconidee are naturally 

 divided on account of very important structural differences. 

 One of these sub-families (the true Heliconinse) consists of two 

 genera only, Heliconius and Eueides, the other (the Danaoid 

 Heliconinte) of no less than sixteen genera ; and, in the in- 

 stances of mimicry we are now discussing, one of the pairs or 



1 Professor Meldola informs me that he has recorded another case of 

 mimicry among British moths, in which Acidalia snbsericata imitates Asthena 

 candidata. See Eat. Mo. Mag., vol. iv. p. 163. 



