INTRODUCTION. 77 



proaching incapacity either to defend itself or to flee 

 from danger, the caterpillar, having now completed 

 its full growth, generally abandons the plant on 

 which it fed, and seeks a secure retreat, or some 

 fixed and stable object to which it may adhere. It 

 is in consequence of this precaution that we so of- 

 ten find chiysalides in the holes of old buildings, in 

 the fissures of timber, &c. or attached to walls, posts, 

 and trees, as the latter afford more permanent secu- 

 rity than the weak and perishable herbaceous plants 

 which so many caterpillars frequent during their vo- 

 racious days. Having selected a proper place, the 

 animal commences its curious proceedings, which 

 terminate in the ejection of its skin, the evolution 

 of the chrysalis, and the suspension of the latter by 

 means of a cord of silk. As chrysalides are sus- 

 pended in two different ways, either perpendicularly 

 by the tail, or horizontally by means of a band round 

 the middle, the proceedings of the caterpillars ne- 

 cessarily vary accordingly, and it will therefore be 

 requisite to advert successively to each. 



When the chrysalis is to be suspended by the tail 

 with the head downwards, the first operation of the 

 caterpillar is to cover a portion of the suiface to 

 which it is to attach itself with a layer of silken 

 threads, which readily adhere in consequence of 

 their viscosity. Each successive layer covers a 

 smaller space than that which preceded it, so that 

 they form, when completed, a little hillock of silk, 

 approaching to the figure of a reversed cone. lute 



