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LETTER XV. 



HABITATIONS OF INSECTS continued. 



THE habitations of insects which I shall next proceed to describe are those 

 formed by the united labour of several individuals. The societies which 

 thus combine their operations may be divided into two kinds : 1st, those 

 of which the object is simply the conservation of the individuals composing 

 them ; and 2ndly, those whose object is also the nurture and education of 

 their young. To the last head belong bees, wasps, c. : to the former the 

 larvae of some species of moths, whose labours, being the most simple, I 

 shall first describe. ; 



You cannot fail to have observed in gardens the fruit trees disfigured, as 

 you would probably think them, with what at first view seem very strong 

 and thick spiders' webs. If you have bestowed upon these webs the 

 slightest attention, you must have likewise remarked that they differ very 

 materially in their construction from those spun by spiders, inclosing on 

 every side an angular space, and being besides filled with caterpillars. 

 These are the larvae of Porthesia ckrysorrhcea, and the web which contains 

 them is spun by their united labour for the protection of the common 

 society. As soon as the cluster of eggs deposited by the parent moth is 

 hatched, the young caterpillars, to the number of three or four hundred, 

 commence their operations. At first they content themselves by forming 

 a sort of hammock of the single leaf upon which they find themselves 

 assembled, covering it with a roof composed of a number of silken threads 

 drawn from one edge to the other ; and under one or more of these tem- 

 porary habitations they reside for a few days, until they are become large 

 and strong enough to undertake a more solid and spacious building suffi- 

 cient to contain the whole society. In constructing this new habitation, 

 they spin a close silken web round the end of two or three adjoining twigs 

 and the leaves attached to them, so as to include the requisite space. 

 They are not curious in giving any particular form to the edifice : some- 

 times it is flat, often roundish, but always more or less angular. The 

 interior is divided by partitions of silk into several irregular apartments, to 

 each of which there is purposely left an appropriate door. Within these 

 the caterpillars retire at night, or in rainy weather, quitting the nest on 

 fine days, and dispersing themselves over the neighbouring leaves, upon 

 which they feed. Here, too, they repose during the critical period of the 

 change of their skins. On the approach of winter the whole community 

 shut themselves up in the nest, which, by the addition of repeated layers 

 of silk, has at this time become so thick and strong as to be impervious to 

 the wind and rain. They remain in a state of torpidity during the cold 

 months, but towards the beginning of April are awakened to activity by 



