56 BRITISH BUTTERFLIES. 



silk, and on which it obtains a firm foothold, resting thereon the 

 greater part of the day, basking in the sun, the leaves being usually at 

 such a slope that they get an almost vertical exposure, whilst to feed they 

 often prefer to go to a neighbouring spray, so as not to interfere with 

 their carefully prepared resting-platform. Of the protective value of 

 this particular resting-position, Chapman says (Ent. Rec, ix., p. 193): 

 " The larva at rest, seen from whatever direction, exactly imitates 

 some aspect of leaves or buds under the different effects of light and 

 shade, and it is thus possible for an untrained eye, in many instances, 

 to look at it, and for it, some time before seeing it. The yellow lateral 

 line resembles the midrib of the leaf seen from above or below, accord- 

 ing to light ; the colour and apparent texture of the skin are the same 

 as those of many leaves. The extraordinary head, with its coloured 

 jaws and spines, suggests, in many aspects, the little group of buds at 

 the extremity of the branches. One has often to look a second time at 

 certain leaves and branches, as well as at the buds, to be sure that they 

 are parts of the tree and not a larva. The curiously- coloured circles on 

 the back of the abdominal segments 3 and 5, which are more brilliant 

 with their blue and yellow than anything in an Arbutus leaf, neverthe- 

 less produce exactly the effect of certain little rings of fungus, or decay, 

 that are very common on the leaves." But the larva of Basilar chia 

 arthemis is said, by Scudder, to further use its silk-spinning habits for 

 protective purposes in a most remarkable way, for he says that the 

 young larva makes a loose ball about the size of a small pea, out of 

 bitten scraps of leaf held together by strands of silk, and this it 

 attaches by a thread to the stripped midrib, on which it is resting, as 

 described above, so that it is moved by every breath of wind, a device, 

 perhaps, to distract from itself the attention of an enemy, for, by 

 constant removals, it is always kept close to the eaten edge of the leaf, 

 while the posterior of the larva is as far out on the stripped midrib as 

 it can find a good footing ; after the second moult it no longer makes 

 this remarkable little packet. 



Although less usual among butterfly larvae, some species use the 

 means of escape that is so frequent among the larvae of certain groups 

 of moths, viz., when disturbed, of allowing themselves to drop rapidly 

 from their position of rest by a silken thread attached to a leaf. 

 Such among our British species are Chrysophanus dispar, Hesperia 

 malvae, etc., and Scudder observes that, in America, Strymon titus and 

 Hypatus bachmanii have the same habit. It is certainly more 

 frequently observed among young, than in older, larvae. 



The final stage usually brings out the silk-spinning possibilities 

 of the larva to their greatest extent. For the purpose of pupation, 

 almost all butterfly larvae, however little silk-spinning they do 

 during their larval life, do some spinning at this period. 

 Few, except the Urbicolids and Parnassiids, spin silken cocoons, 

 i.e., silken webs in which to pupate, but almost all spin at 

 least a thick silken pad to which the pupa is attached by its 

 anal cremastral hooks, and many spin, in addition, a silken 

 girth, or support, round the body, which acts as a girdle when 

 pupation takes place. There are, however, many intermediate stages 

 between the coarse, but slight, silken cocoon of the Parnassiids, in 

 which the pupa lies loosely, and the merely suspended butterfly pupa, 

 whose larva has spun a silken pad before pupation, and from which it 



