THE SILK-SPINNING HABIT IN BUTTERFLY L.AHYM. 55 



and prevents from falling, by silk spun over its extremity and the 

 twig on which it grows. The leaf is then spun carefully together and 

 becomes crumpled as it dries during the winter. Into this the larva 

 crawls, and, in this, it hides during the period of hybernation. So 

 firmly is the hybernaculum fixed to the twig, that it can have no 

 independent movement, and it resembles so exactly a dead leaf clinging 

 to the stem, that it is sure to escape observation. When Apatura iris 

 spins its hybernaculum, it not only covers the twig with a silken pad, 

 to which it may firmly cling, but also envelopes the hinder part of its 

 body in a silken covering. The hybernaculum of the larva of 

 Basilarchia archippus appears to be as interesting. Scudder says that 

 the larva hybernates when partly grown, and provides for the occasion 

 a winter residence, which is occupied only during the cold season. 

 For this purpose, it eats the side of a willow-leaf nearly to the midrib, 

 for about one-third the distance from the tip, ordinarily selecting for 

 the purpose, a leaf near the end of a twig ; it brings together the 

 opposite edges of the leaf, and not only fastens them firmly with silk, 

 but covers this nest outside and inside with a carpet of light-brown, 

 glossy silk, so that the leaf is nearly hidden, nor is this all, it travels 

 back and forth on the leafstalk and around the twig, spinning its silk 

 as it goes, until the leaf is firmly attached to the stalk, and, in spite of 

 the frost and wind, it will easily hang until spring. Following the 

 projecting midrib, the caterpillar creeps into this dark cell, head 

 foremost, and closes the opening with its hinder segments, all abristle 

 with spines and warts. The other species of the same genus, 

 B. arthemis and B. astyanax have similar habits, the former feeds on 

 birch, and, if one examines these trees in early spring, one can hardly 

 fail to be struck by the deceptive resemblance that these hybernacula bear 

 to the opening buds and curving terminal shoots of the very twigs on 

 which they occur ; the colour of the soft down of the buds, and the 

 enveloping silk of the hybernacula are as similar as are their forms, and this 

 mimetic resemblance is doubtless as effective as it is interesting. The 

 larva of B. arthemis spins its hybernaculum when about half -grown, and, 

 selecting a growing leaf of birch, it eats away the apical third or fourth, 

 excepting the midrib and a narrow flange on each side of it, or it uses 

 the leaf it has been eating, already trimmed in this fashion ; it then 

 draws together, above, the outer edges of the uneaten portion to construct 

 a tube, which it lines very heavily with brown silk, within and without, 

 and further binds the leafstalk to the stem with repeated bindings of 

 silk to prevent its falling to the ground in winter ; by means of the 

 ledge formed by the projecting midrib, it then enters the tube head 

 foremost, and completely fills it, so that the opening is just closed by 

 the roughened end of the body. 



Although nothing to do with the silk-spinning of the hybernaculum, 

 we may here mention the peculiar habit of Basilarchia arthemis, of 

 retiring, after a meal (made of a birch leaf), to the stripped midrib to 

 rest, fastening to it, however, minute bits of leaf with an abundance of 

 silk in order to strengthen it, whilst Chapman describes the much more 

 complicated silk-covered platform, made by the larva of Charaxes jasius, 

 and which, in the Esterel, it spins on the south side of an Arbutus tree, 

 low enough down to have the upper part of the tree as a protection and 

 shelter. . The larva either clothes the surface of a leaf with silk, or 

 fastens together several leaves, which it then similarly covers with 



