304 



LETTER XV. 



HABITATIONS OF mSECTS— continued. 



The habitations of insects which I shall next proceed to describe are 

 those formed by the united labor 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 2dly, 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 

 labors, 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 chrysorrhcea, and the web which con- 

 tains them is spun by their united labor 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 root 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 sufficient 

 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 : sometimes 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 left purposely an appropriate door. Within these the caterpillars 

 retire at night, or in rainy weather, quitting the nest on fine days, and dis- 

 persing themselves over the neighboring leaves, upon which they feed. 

 Here, too, they repose during tiie 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. Tiiey remain in a state of torpidity during the cold months, but 

 towards the beginning of April are awakened to activity by the genial 

 breath of spring, and begin to feed with greediness upon the young leaves 



