152 INSECT ARCHITECTURE. 



When they have devoured all the leaves, or at least 

 those which are most tender and succulent, they abandon 

 their first camp, and construct another contiguous to it 

 under a tuft of fresh leaves. Several of these encamp- 

 ments may sometimes be seen within the distance of a foot 

 or two, when they can find plantain {Plantago lanceolata) 

 fit for their purpose ; but though they prefer this plant, 

 they content themselves with grass if it is not to be pro- 

 cured. 



When they are about to cast their skins, but particu- 

 larly wlien they perceive the approach of winter, they 

 construct a more durable apartment in the interior of their 

 principal tent. The ordinary web is thin and semi-trans- 

 parent, permitting the leaves to be seen through it; but 

 their winter canvas, if we may call it so, is thick, strong, 

 and quite opaque, forming a soi't of circular hall without 

 any partition, where the whole community lie coiled up 

 and huddled together. 



Early in spring they issue forth in search of fresh food, 

 and again construct tents to protect them from cold and 

 rain, and from the mid-day sun. 



M. Reaumur found upon trial, that it was not only the 

 caterpillars hatched from the eggs of the same mother 

 which would unite in constructing the common tent ; for 

 different broods, when put together, worked in the same 

 social and harmonious manner. We ourselves ascertained, 

 during the present summer (1829), that this principle of 

 sociality is not confined to the same species, nor even to 

 the same genus. The experiment which we tried was to 

 confine two broods of different species to the same branch, 

 by placing it in a glass of water to prevent their escape. 

 The caterpillars which we experimented on were several 

 broods of the brown-tail moth (^Porthesia aurijiaa), and 

 the lackey (Clisiocampa- neustria). These we found to 

 work with as much industry and harmony in constructing 

 the common tent as if they had been at liberty on their 

 native trees ; and when the lackej^s encountered the 

 browTi-tails they manifested no alarm nor uneasiness, but 

 passed over the backs of one another, as if they had made 



