FAMILY HABITS IN BUTTERFLY LARV.E THE PAPILIONIDS. 31 



spots are very conspicuous. Trouvelot notes (Proc. Bost. Nat. Hist. 

 Soc. } xii., p. 92) that, on a lilac-leaf, the silk was so spun that, on a 

 wet morning, it acted as a real bridge, built over a torrent. The 

 larva, however, still hangs with its body almost vertical, Fitch noting 

 that, on an apple-leaf, the weight of the larva inclines the leaf almost 

 to the perpendicular, the leaf and larva swinging in the wind. 



The young larva of Euphoeades troilus makes a little hiding-place by 

 folding over a portion of a leaf near the apex, and, in this, rests when 

 not feeding, the deepest part of the nest being somewhat cylindrical, 

 so that an opening of about 3mm. in diameter is found at the end 

 away from the tip of the leaf, through which the larva finds ample 

 room to creep even after it has passed its first moult, which it does in 

 this chamber, whilst larvae are sometimes to be found therein even at 

 the beginning of the third stage, but, as it increases in size, it uses the 

 whole of one side of a leaf, constructing a long, and rather narrow, 

 flattened cylinder, lined with silk, out of which it can crawl at either 

 end, when it leaves this retreat to go to other leaves for food ; as it 

 increases in size, a still larger portion of a leaf is utilised, until, in its 

 last stage, it takes up a position on the midrib, and spins over the two 

 halves of the blade of the leaf till they meet exactly above its back. 

 It thus passes its entire larval life, except when feeding, in conceal- 

 ment, undergoing its ecdyses within its cleanly home, for in this it 

 drops no excrement, nor does it suffer any of its exuviae to remain, 

 eating up its cast-ofT skin, and even thrusting its no longer needed 

 skull-cap out upon the ground. Buckler also notes {Larvae Brit. 

 Butts., etc., i., p. 2) that the larva of Papilio machaon eats its cast 

 skin except the head-piece, and further, that he once observed a larva, 

 that found a speck of frass on its food, pick it up in its jaws, stretch 

 out its body, and somehow project the frass away from the plant. On 

 the other hand, Scudder (Butts. New England, p. 1360), speaking of 

 the moulting-habit of Papilio pohjxenes, says that the cast skin is not 

 eaten. The larva of this species, like that of P. machaon, rests 

 exposed, and, when about to moult, selects a very open position, 

 frequently the top of a stem, where it rests head upwards, apparently 

 to avoid the danger of being rubbed at that time by the neighbouring 

 leaves moved by the wind. 



Whilst the adult larva? of the species just mentioned largely exhibit 

 distinct warning colours, and rest more or less exposed, the larvae of 

 that group of Papilionids of which Iphiclides podalirius is an excellent 

 example, are, as a rule, green in colour, delicately marked with pale tints 

 laterally, and take up a position at rest in which the larva bears, by 

 colour and position, an exact and detailed resemblance to the part of 

 the plant on which it rests absolutely immovably unless feeding. In 

 such, cases the resting-habits usually aid the cryptic effects produced 

 by the coloration of the larva, and a lethargic immovable habit is 

 particularly frequent in the shrub-feeding, as opposed to the umbellifer- 

 and Aristolockia-iee&mg, groups in which an exposed resting-habit is 

 usual. 



Although somewhat closely allied to Iphiclides podalirius, the larvae 

 of I. ajax develop much more striking and definite colours than those 

 of the former, yet Scudder considers that these brighter colours are 

 not merely warning colours to show off the inedibility of the larvae, 

 but have a cryptic effect, the stripes particularly growing obsolescent 



