34 BRITISH BUTTERFLIES. 



little use of silk, even when undergoing ecdysis, a fact perhaps due 

 partly to its living always on the underside of the leaves or upon the 

 stems of its foodplant, partly to the fear of betraying its presence. 

 Scudder states that the larva? of the Nearctic genus, Jasoniades, spin a 

 silken web over a whole leaf of the foodplant, and so draw the sides 

 together, hiding in the trough thus made; when not feeding, Edwards 

 says that the young larva of Jaaoniadea glaucus takes up its position on 

 the upperside of a leaf, over which it spins a bed of silk, and that the 

 leaf, as it increases in size, is somewhat drawn together, so that the 

 leaves on which larva? are resting can readily be distinguished, whilst 

 he adds that the larva of J. rutulua, like the last, also weaves a web 

 across the upper surface of a leaf which is also somewhat drawn 

 together, the firmly-drawn web serving as a bridge on which the larva 

 rests, and leaving an open space below between the web and the leaf. 

 Scudder observes (Butt*. New Engl., p. 1322) that the young larva of 

 Kuphoeades troilits bites out a channel down one side of a leaf about 

 l-5cm. from the tip, straight or a little obliquely to the midrib, folds 

 over the flap thus obtained upon the upper surface of the opposite side, 

 the larva living in the depth of the cavity thus made ; this cavity it 

 covers next the midrib with repeated crossings of transverse strands of 

 silk, so as to form a dense glistening whitish carpet, thickest in the 

 middle, and extending the whole length of the enclosure made ; if 

 forced open by hand the flap at once regains its former position when 

 freed, showing the tenseness of the silken strain. As the larva gets 

 larger, it chooses a larger portion of leaf, until, in its final stadium, it 

 spins a silken floor along the midrib, carries the spinning over to each 

 half of the blade until the transverse silken bands arch the two halves 

 over so as to meet above its back, and thus forms a cylindrical silk- 

 lined chamber in which it lives. Aitken and Davidson observe (Journ. 

 Bomb. Nat. Hist. Soc, v., pp. 363 et se<j.) that the larvae of the 

 " agamemnon group " of Papilios are extremely shy and cautious, rest- 

 ing motionless most of the day on the upperside of a leaf, along the 

 midrib,, with the head towards the stalk ; the leaf on which they rest 

 being usually carpeted with silk. 



The specialisation of food-habit, and its modifications among the 

 Papilionids would, were we able to deal with it at length, make an 

 interesting chapter. We can, however, here merely refer to the 

 specialisation of food-habit in the Thaids and Parnassiids, the larvae of 

 the former being practically confined to Aristolochia for their food- 

 plants, whilst the latter appear to be just as restricted to plants of 

 the natural order Crassulaceae — saxifrages, etc. The various Papilionine 

 tribes also specialise largely in this direction, e.g., the " tnachaon 

 group" select mainly plants belonging to the Umbelliferae, the 

 " podalirius group," those belonging to Rosaceae, the "philenor group,"' 

 to-4mtoZflt7i?'a,etc.,butareally useful study of the food-habit in this largo 

 group, would require more space than we can afford. We may. however, 

 note that, of the species of the il mac ha on group," we find that Papilio 

 machaon itself, although feeding in nature on a variety of I "mbellii'ers, 

 adapts itself easily to others. Floersheim, who has reared large 

 numbers under semi-natural conditions in his butterfly-house, reports 

 {I'lut. lice, xxi., p. 15) that Skimmia oblata appeal's to be its favourite 

 foodplant, the imagines laving more eggs on this than on fennel that 

 grows by its side, and which appears to be second favourite: it also 



