26 BRITISH BUTTERFLIES. 



the races of the species must have been separated for thousands of 

 years, and, in cases where differentiation has gone to the length of 

 developing new species, e.g., Aglais milberti (in Canada), Polygonia 

 faunas (throughout America), and so on, the habits of the representa- 

 tive species are practically identical, e.g., those of Aglais milberti with 

 those of A. urticae, Polygonia faunus with P. c-album, etc. 



Comparing the larval habits of the Vanessids of the Nearctic, with 

 those of the Palaearctic, region, we observe that Scudder remarks 

 (Butts. New England, i., p. 307) : " The Vanessid larvae are solitary or 

 gregarious according as the eggs are laid singly or in masses. Of those 

 that are gregarious, some retain the habit throughout the larval 

 existence, others change the habit when halfgrown. Whilst associated, 

 they spin for themselves a common web, and even the solitary species 

 weave nests, though more of leaves than web." Dealing with the 

 larval habits in detail, Scudder notes (op. cit., p. 435) that " the eggs 

 of the Pyrameids are laid singly, that the larvae live singly, usually in 

 vertical nests, but, whilst the species of the ' atalanta ' group, to 

 which he restricts the term ' Pyrdmeis,' construct their nest of a 

 single leaf, the lower portion of which they gradually devour, the 

 larvae of the ' cardui ' group, for which he coins the term ' Neo- 

 pyrameis,' at least after they are halfgrown, form their nests of 

 several leaves, feeding only upon the parenchyma of the upper surface 

 of the leaves until nearly mature." As showing that the larvae of 

 P. atalanta have exactly the same habit in Europe and North America, 

 Edwards notes (Can. Ent., xv., p. 15) how the young larva encloses 

 itself in a leaf of Boehmeria, and states that, during the first stage, the 

 larva eats the substance of the leaf within the cave, at some distance 

 from the tip, leaving the framework untouched ; he then describes 

 how, in the second stage, it moves to a new leaf, gnaws the midrib, 

 making the leaf to droop, and how this is followed by the construction 

 of its new home, the leaf being completely closed, etc. In fact, the 

 slight variation in the details of the larval habitations are just such as 

 one may find any year, in Britain, when the larvae are fairly abundant 

 on nettle. As Edwards says, " the one occupation of the larval life 

 appears to be to secure privacy." Scudder notes (Butts. New England, 

 p. 466) that "the larvae of P. huntera construct nests of a leaf of 

 Gnaphalium, taking advantage of the silken hairs which prof usely cover 

 the surface of the leaves to form a dense white mat of silk and leaf-hairs, 

 beneath which they take up their abode ; beneath this, the caterpillar 

 devours the soft tissue of the leaf, forming a larger nest as it gets 

 older, drawing two or three leaves together with silken thread, 

 consuming the undersurface of the leaves, and hence making them 

 crisp and blanched, the whitened portions of the leaves, together with 

 the size of the nest occupied by the larva when fully grown, making 

 them conspicuous." The same author's account of the habits of the 

 larva of P. cardui (op. cit., pp. 482-3) shows that they are precisely 

 the same as those so well-known to us in Europe. 



It is remarkable how nearly the larvae of the Nearctic Poly- 

 gonias, of which there are several species, agree in their habits 

 with those of our own area. Of the former, Scudder observes 

 (op. cit., p. 314) : " The caterpillars of the Polygonia species 

 feed almost exclusively on Urticaceae and Grossulaceae, usually 

 resting on the underside of the leaves, sometimes partially con- 



