FAMILY HABITS IN BUTTERFLY LARV^I THE PAPILIONIDS. 27 



that it seems very loth to use its osmaterium even when disturbed ; the 

 yellow osmateria of Papilio polygenes are, on the other hand, said to be 

 protruded on the slightest provocation, and emit a strong and disagree- 

 able odour, not very dissimilar to that of the bruised leaves of their 

 foodplant. The same observer says that, when the larva of Laertias 

 philenor protrudes its osmaterium, a scarcely perceptible odour is emitted 

 that is not altogether disagreeable, though difficult to describe. 

 Lacordaire states (Ami. Soc. Ent. Fr., ii., p. 385) that the osmateria of 

 Iphiclides podalirius emit an odour that resembles that of musk. 

 Mathew gives some details of the larvaB of the A ristolochia- feeding 

 Papilios of the Pacific Islands and Australia, and he observes (Trans. 

 Ent. Soc. London, 1888, pp. 106 et seq.) that the larvas of Ornithoptera 

 durvilliana and 0. pronomus have deep carmine-coloured osmateria 

 which are protruded at once when the larva3 are annoyed, whilst, of 

 the Citrus- (orange, lime, etc.) feeding larvae, he observes (op. cit., p. 

 174) that, when irritated, the larvaB of Papilio erectheus protrude their 

 two long carmine-coloured osmateria, and that, whilst the tentacles are 

 exposed, a disagreeable odour of rotten oranges is distinctly perceptible; 

 the larva of this species also, when nearly full-grown, sways itself from 

 side to side with a tremulous motion if annoyed. He further notes 

 (pp. cit. p. 177) that, when disturbed, the larva of Papilio anactus 

 protrudes its orange-coloured osmaterium, emitting at the same time 

 an unpleasant perfume of rotten oranges. 



It is to be observed that the scent (objectionable or otherwise to our 

 human nostrils) is often noted as bearing some strongly concentrated 

 property of the food-plant, the umbellifer-feeding Papilionid larvae 

 giving out an odour in which the peculiar fennel, carrot, or allied 

 properly is distinctly traceable; similarly, the scent of the Aristolochia- 

 feeding larvae contains, usually, a marked odour of the food-plant, the 

 orange-feeders that of orange, etc. It is further generally assumed, 

 apart from the fact that the tissues of the larva themselves are impreg- 

 nated with the essential odour of the food-plant, that the smell given off 

 from the osmateria is protective to the caterpillar, but the total 

 evidence on the point is very small, the strongest being that of Neal 

 (quoted supra) relating to the larvae of Heraclides cresphontes. 

 We have already noted (supra) that Davidson and Aitken 

 consider that the secretion of the osmateria of the larvaB of 

 the Indian Aristolochia-feeding Ornithopteras is designed 

 for defence against hymenopterous and dipterous parasites, etc., yet 

 they note that they have counted as many as 67 larvaB of a little 

 hymenopterous parasite emerge from a single larva of Papilio hector, 

 which, of course, is no proof that even this species is not protected, and, 

 as bearing directly on the point, Mathew notes (Trans. Ent. Soc. Lojid., 

 1888, p. 174) that, whilst the larva of Papilio erectheus, which gives 

 out a smell of rotten oranges, does not appear to suffer from the 

 attacks of ichneumons or any other parasite (so far as his observations 

 go), yet they are most assiduously hunted by a little bird, Zoster ops caeru- 

 lescens, which, no doubt, he adds, prevents this butterfly from causing 

 immense mischief in the orange orchards. Similarly, the same sort 

 of smell given off by Papilio anactus, appears to be no protection 

 against the same bird, which eagerly devours the young larvae. 

 Floersheim observes (Ent. Rec, xviii., p. 39) that he has observed 

 spiders and larvae of ladybirds attack and kill young larvae of Papilio 



