SOCIAL CATERPILLARS. 073 



cateri)illai\s of l)uttcrfiics arc rarely f'ouncl in company. It is at this stage, 

 too, that iu many instances, the winter season overtakes the caterpiHar 

 and it hibernates ; and since in the spring it revives when the pLants liave 

 put fortli l)iit tender leaves, impossible to nourish more than one or at 

 most two such ravenous beasts as now come out of their winter quarters, 

 such a change of habit would seem to be compulsory. Possibly the change 

 in habit which generally takes place at this middle period of caterpillar 

 life, e^■en when winter does not intervene, is an inheritance from a com- 

 mon ancestor whose habits were fixed by the necessity of hibernation at 

 this age. 



As far as our own fauna is concerned, the great mass of social cater- 

 pillars are found in the highest family, the Nym[)halidae, and indeed in 

 the subfamily of the Nymphalinae, in which this habit is found in most of 

 the principal groups. In some instances, as we have related of Laertias 

 philenor, the caterpillars in early life live exposed upon the surface, gen- 

 erally the under surface, of the leaf, ranged side by side, feeding and 

 sleeping in unison. But in most some sort of web is constructed by the 

 caterpillars upon or Ijeneath which they live, and to which, should they 

 wander beyond its limits for food, thev retire for rest and moultino:. Some 

 use this web with certain alterations in its structure as a winter residence, 

 but then invariably leave it on the approach of spring and part company, 

 though often being still found in near proximity. Others leave it at the 

 hibernating season to seek, each for himself, his own hiding place. 



Perhaps of all our caterpillars, although it constructs but a slender web, 

 Euvanessa autiopa is the most preeminently social. The eggs are laid in 

 a cluster of greater or smaller size around a terminal twig, which they 

 leave together and as if by common impulse range themselves side by side 

 in compact rows along a chosen leaf. Even if they are separated forcibly 

 from each other, they come together again and rearrange themselves. 

 When disturbed they will similtaneously strike an attitude of alarm and 

 turn their heads in unison as if Avorked by a machine. The web they 

 form is simply tliat which they make as they crawl about, each following 

 hurriedly in the track of its predecessor, and as it moves adding its thread 

 to the carpet upon which it treads ; and being social throughout their life 

 they are more than usually destructive to foliage, stripping branch after 

 branch, and wandering to the very tips until they are borne down by the 

 weight of the mass. It would seem probable that our Eugonia has the 

 same habits from what we know of its European congener, but if so it is 

 exceedingly strange that in only one instance has the caterpillar been seen 

 in this country, and then but a single one, probably one which was hasten- 

 ing to seek a place in which to pupate. 



Although it is not stated whether the caterpillar concerned belongs to 

 a butterfly or to a moth, a verv curious and interesting case of strict 



