POLISTES. 275 



How the cocoons are made and suspended is quite a mystery. 

 Mr. Westwood offers a suggestion that, before changing into the 

 pupal state, the insect spins its thread to the required length, 

 and, while still suspended at the end of its rope, spins the cocoon, 

 which thus becomes fastened to the thread. In a future page 

 will be described a cocoon woven on a similar plan, but made 

 by the caterpillar of one of the moths. 



Mr. Westwood mentions that when examining the cocoon of 

 the Cryptus, he found that it was composed of three distinct 

 layers, that on the exterior being composed of loose silk, which 

 could be wound off like that of the common silkworm, but 

 that the two interior layers were very shining, smooth, and of 

 a gummy membranous texture, thus agreeing with the cocoons 

 of the Burnet ichneumon. 



OUE last example of the pensUe nests formed by the hymen-, 

 optera is a truly remarkable one. For some time I could 

 scarcely decide upon its place in the present work, whether it 

 was to be ranked as an example of the pensiles, social insects, 

 or builders. On account, however, of the locality which is chosen 

 for it, and the peculiar method by which it is attached to the 

 branch, I have decided upon placing it among the pensile nests. 



It has already been mentioned that the members of the genus 

 Polistes are in the habit of building their cells in the open air, 

 and leaving them without covering to defend them. 



The shape, material, and arrangement of the comb is ex- 

 tremely variable; some, as that which has already been men- 

 tioned, hanging their ceU-masses to the branches, just as if a 

 number of bee-combs were simply hitched on the twig by the 

 simple process of boring a hole in the upper part of the comb, 

 and pushing the twig through it ; others, again, make their cells 

 of mud, in a nearly globular shape, and fasten them on the 

 branches like so many berries. The species, however, which 

 make the cells represented in the illustration, is one of the most 

 remarkable, and so elegant is the form of the combs, and so 

 sin<nilar the method of their attachment, that I have had them 

 drawn nearly of the natural size. 



Generally, the shape of the comb is nearly round, as is seen in 

 the upper figure of the illustration. The cells are remarkable 

 for their radiating form, the bases being a trifle smaller than the 



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