THE GOLD-TAILED MOTH. 271 



Most caterpillars wage war singly on the foliage, and though 

 they do much damage, their ravages are conducted in a desul- 

 tory manner. The Small Ermines, however, band themselves 

 together in hosts, and march like disciplined armies to the 

 attack, invading a district and completely devastating it before 

 they proceed to another. 



They live in large tents, placed among the branches of some 

 tree, and composed of silken threads, which are loosely crossed 

 and recrossed in various directions. From this centre the 

 caterpillars issue in vast numbers, each individual spinning a 

 strong silken thread as it proceeds, which acts as a guide to the 

 nest, just as the fabled clue led through the intricacies of 

 Rosamond's bower. When once these caterpillars have taken 

 possession of a tree, they are sure to strip it of its leaves as 

 completely as if the foliage had been plucked out by hand. It 

 is a very curious sight to watch the systematic manner in which 

 these troublesome insects set about their work, how they send 

 out pioneers which lead the way to new branches, either by 

 crawling up to them or by lowering themselves to them by 

 means of their silken life-Unes, and how soon they are followed 

 by their ever-hungry companions. 



Another well-known British insect which constructs social 

 habitations is the Gold-tailed Moth (Porthesia chrysorrhcea), 

 2l familiar and beautiful insect, with wings of soft downy 

 plumage, and snowy-white in colour, and a tuft of yellow hair 

 at the end of the tail. The perfect insect may often be seen 

 sticking on the trunks of trees in gardens, waiting until the 

 evening, when it will fly off to its labours. 



When the moth has laid its eggs, it plucks off the beautiful 

 yellow tuft at the end of the tail, and with it forms a roof over 

 the pile of eggs, laying the hairs so artificially as to make a 

 perfect thatch. When the larvae are hatched, they retain their 

 sociabiHty, and spin for themselves a common domicile. This 

 house is very remarkable. Viewed on the exterior, it is seen 

 to be a bag-like structure of whitish silk, rather strong and 

 tough, but very yielding. 



One of these nests, which I found in Wiltshire, is now before 



