THE COLORATION OF BUTTERFLY LARV^. 71 



those that, upon a bright green or olive ground, find all their conspicuous 

 markings in dark stripes encircling, or almost encircling, the body, and 

 which are generally especially conspicuous upon the upper surface, such 

 being notably the case in the genera Iphiclides, Papilio and Anosia, and 

 less so in Cinclidia and Euphydryas; or, he says, the "lighter and 

 darker colours of the body may segregate in a more massive way, and 

 exceedingly conspicuous broad bands follow the length of the body, as 

 in some of the Melitaeidi of Europe ; or they may congregate in large 

 dorsal saddle-like patches, as in all our species of Basilarchia, and in 

 several of the Papilionines, either in their earlier or later stages, 

 as has already been noted and dealt with at length (supra). Indeed, 

 it is in the latter that we find, perhaps, on the whole, the most 

 striking and extraordinary freaks of colouring to be found among 

 butterfly larva?, the great variety, even among the few genera inhabiting 

 North America, being only an intimation of what may be found in 

 tropical countries where the family is so much more fully represented. 

 The eye-like spots of the swollen anterior segments, coloured in such 

 an extraordinary and admirable manner, the opalescent and jewelled 

 dots which besprinkle the dorsal surface, the brilliant fleshy appendages 

 which sometimes adorn the sides ; the frequent contrasts of such colours 

 as bright orange and velvety- black, not to mention the curious differ- 

 ences in the markings between the earlier and later stages, reveal the 

 possibilities of natural selection in the adornment of caterpillars. 

 These brilliant colours are perhaps only possible by their possession 

 of protective osmateria." 



It will be observed above that under the generic name Iphiclides, 

 two species with larva? showing very different modes of protection 

 have been noted, viz., Iphiclides podalirius and I. ajax. Both these 

 agree in attaining adult coloration with the second instar, but this 

 adult coloration develops on entirely different lines in the two species. 

 In I. podalirius its colours are so definitely cryptically protective that 

 one cannot fail to mark them ; in I. ajax the colours are brighter, the 

 markings are in the form of somewhat brilliant stripes, but Scudder 

 doubts (antea p. 67) them being merely " warning colours to show off the 

 inedibility of the larva," and particularly adds later {antea p. 70), 

 that " the stripes of I. ajax grow obsolescent towards maturity and leave 

 the larva more completely green." That the difference in the markings 

 of the larva? of these two closely allied species is more or less definitely 

 " cryptic " and " warning " respectively, appears, however, to be further 

 borne out by the nature of the osmateria scents, for, whilst that of I. poda- 

 liriusis quite pleasant and fruit-like, and certainly not offensive, that of I* 

 ajax is described by Edwards (teste Scudder, Butts. ISIew England, 

 p. 1273) as being " a peculiarly acrid and sickening odour, which must 

 effectually protect them," and, in a letter, Edwards adds that he does 

 " not believe a starving bird would touch one, the stench being so 

 strong as nearly to turn one's stomach." 



Bacot thinks that the cryptic coloration of the adult larva of 

 I. podalirius is more effective on some foodplants than others. He 

 opines that, on blackthorn, when viewed laterally, the cryptic appear- 

 ance of the larva is very good ; viewed dorsally, the rust-red spots fit 

 in well with the notch in hawthorn, but are out of place for black- 

 thorn ; on the plant which it mostly affects at Martigny, a species of 

 wild cherry, with leaves more suggestive of pear, it did not seem to be 



