IMPERFECT SOCIETIES OF INSECTS. 301 



merits, which is pitched over some of the plants that constitute their 

 food, and shelters them both from the sun and the rain. When they have 

 consumed the provision which it covers, they construct a new one over 

 other roots of this plant ; and sometimes four or five of these encamp- 

 ments may be seen within a foot or two of each other. Against winter 

 they weave and erect a stronger habitation of a rounder form, not divided 

 by any partitions, in which they lie heaped one upon another, each being 

 rolled up. About April they separate, and continue solitary till they 

 assume the pupa. 



Reaumur, to whom I am indebted for this account, has also given us 

 an interesting history of another insect, the gold-tail moth (Porthesia 

 chrysorrhcea) before mentioned, whose caterpillars are of this description. 

 They belong to that family of Bombycidce which envelop their eggs in 

 hair plucked from their own body. As soon as one of these young cater- 

 pillars is disclosed from the egg, it begins to feed ; another quickly joins it, 

 placing itself by its side ; thus the^ proceed in succession till a file is 

 formed across the leaf: a second is then begun ; and after this is com- 

 pleted a third, and so they proceed till the whole upper surface of the 

 leaf is covered : but as a single leaf will not contain the whole family, 

 the remainder take their station upon the adjoining ones. No sooner 

 have they satisfied the cravings of hunger, than they begin to think of 

 erecting a common habitation, which at first is only a vaulted web, that 

 covers the leaf they inhabit, but by their united labours, as I have de- 

 scribed in a former letter, in due time grows into a magnificent tent of silk, 

 containing various apartments sufficient to defend and shelter them all 

 from the attacks of enemies and the inclemency of the seasons. As our 

 caterpillars, like eastern monarchs, are too delicate to adventure their feet 

 upon the rough bark of the tree upon which they feed, they lay a silken 

 carpet over every road and pathway leading to their palace, which ex- 

 tends as far as they have occasion to go for food. To the habitation just 

 described, they retreat during heavy rains, and when the sun is too hot : 

 they likewise pass part of the night in them ; and, indeed, at all times 

 some may usually be found at home. Upon any sudden alarm they 

 retreat to them for safety, and also when they cast their skins : in the 

 winter they are wholly confined to them, emerging again in the spring : 

 but in May and June they entirely desert them ; and, losing all their love 

 for society, live in solitude till they become pupa3, which takes place in 

 about a month. When they desert their nests the spiders take possession 

 of them ; which has given rise to a prevalent though most absurd opinion, 

 that they are the parents of these caterpillars. 1 



With other caterpillars the association continues during the whole of 

 the larva state. De Geer mentions one of the saw-flies (Serrifera) of this 

 description which form a common nidus by connecting leaves together with 

 silken threads, each larva moreover spinning a tube of the same material 

 for its own private apartment, in which it glides backwards and forwards 

 upon its back. 2 I have observed similar nidi in this country ; the insects 

 that form them belong to the Fabrician genus Lyda. 



A small East Indian hair-streak butterfly (Thecla Isocrates), of whose 

 economy Mr. Westwood has given an interesting account, resides in the 

 larva state in small societies of at least seven or eight individuals in the 



1 Eeaumur, ii. 125. 2 De Geer, ii. 1029. 



