PART III. ARBORETUM AND FRUTICETUM. 



•2565 



The number of inhabitants in a colony varies from 100 to 200; and, hence, 

 the more numerous the colony, the more frequently is a change of residence 

 required. These webs consist of a great number of threads, not unlike spider 

 webs, arranged somewhat irregularly, but sufficiently loose to enable the in- 

 habitants to be seen through the covering. The caterpillars eat only the 

 parenchyma of the upper side of the leaf; they also arrange their threads 

 longitudinally, each, apparently, having a thread of its own, along which 

 it moves either backwards or forwards without disturbing its neighbours, 

 which, when in repose, are arranged side by side. The larger-sized nests 

 include several of the smaller branches or twigs with their leaves ; and some 

 parts are of a firmer texture than the rest, apparently for resisting the wet. 

 When the parenchyma of the upper sides of the leaves enclosed in the web 

 has been consumed, the nest is abandoned, and a new one made, enclosing 

 a fresh bunch of twigs, each of the caterpillars spinning a considerable number 

 of threads ; and thus each colony constructs as many as 6 or 8 distinct webs, 

 disfiguring the tree, especially when, as is often the case, there are many 

 societies established upon it. The leaves, thus half-consumed, wither up, as 

 well as the young branches, for want of support, and the tree assumes the 

 appearance of having been entirely scorched up with fire. The caterpillars 

 rarely quit their nests ; but, when alarmed or disturbed, they endeavour to 

 make their escape by spinning a long thread, and dropping to the ground. 

 When touched, also, they writhe about with great activity, and will run 

 backwards nearly as fast as forwards. 



" When full grown, about the beginning of July, each caterpillar encloses 

 itself in a long and nearly cylindrical cocoon of white silk (^fig. 2464'. d), of 



24(5-1. 



a leathery consistence ; and these cocoons are arranged side by side at one 

 end of the nest, forming a mass not unlike, only considerably larger than, 

 a mass of ants' eggs, as the cocoons of the ant are commonly called. As the 

 whole of a colony has been reared from one brood of eggs, it is generally the 

 case that the entire number commence the construction of their cocoons at 

 the same time, and the whole are generally completed in the same day. In 

 this cocoon, the insect immediately undergoes its change to the chrysalis 

 state {fig. 2464. c); and its chrysalis, which does not materially differ from 

 those of other small lepidopterous insects, is of a shining chestnut colour. 

 It differs, however, from the chrysalides of the leaf-rollers, in wanting the 

 transverse series of hooks with which the abdominal segments of the latter 

 chrysalides are furnished ; and hence, when, at the expiration of about 20 

 days, the perfect insect is ready to come forth, being unable to work the 

 chrysalis out of the cocoon, the escape of the imago is effected within the 

 latter, and the moth, with its wings in an unexpanded state, makes its way 

 out of one end of the cocoon, after which its wings soon spread to their full 

 size. 



" The perfect insect is shown at c in Jig. 2464., with its wings expanded, 

 and magnified ; / is the same, witli its wings closed, and of the natural size; 

 and g, the caterpillar, rather magnified. — J. O. JV." 

 P. (c.) angustifolia. 909., deie the (c). 



Additional Species of Pi/rus belonging to the § Mains. 9 1 0. 

 " P. ? Schott'i Ledeb. There is a plant in the Horticultural Society's 

 Garden, received, under this name, from Dr. Ledebonr. 



" P. sfipnldcen Hort. There are plants in the Horticultm-al Society's 



8 (■ 4 



