MODE OP SUSPENSION. 291 



experiment to stop them with wax, in order to see whether the 

 inclosed insect could be developed when the air was thus ex- 

 cluded. I believe that there are none of these holes in the 

 cocoon of the large Oak Egger Moth, and if there be any such 

 perforations, they are so minute as to escape notice. 



If the reader will refer to page 274, he will see an account of 

 certain cocoons which are made by hymenopterous insects, and 

 suspended by a single thread from the branches. In Mr. H. W. 

 Bates's work on the natural history of the Amazon River, there 

 is a most interesting account of a pensile cocoon also suspended 

 by a single thread, but which is the work of a lepidopterous 

 insect It will be seen that Mr. Bates was able to see the insects 

 spin the cocoon, and his account exactly tallies with Mr. West- 

 wood's conjecture as to the method by which the creature manages 

 to produce a hollow cocoon at the end of a single thread. Mr. 

 Bates's account is as follows : — 



" The first that may be mentioned is one of the most beautiful 

 examples of insect workmanship I ever saw. It is a cocoon, 

 about the size of a sparrow's egg, woven by a caterpillar in 

 broad meshes, of either buff or rose-coloured silk, and is fre- 

 quently seen in the narrow alleys of the forest, suspended from 

 the extreme tip of an outstanding leaf by a strong silken thread, 

 five or six inches in length. It forms a very conspicuous object, 

 hanging thus in mid-air. The glossy threads with which it is 

 knitted are stout, and the structure is therefore not liable to be 

 torn by the beaks of insectivorous birds, while its pendulous 

 position makes it doubly secure against their attacks, the appa- 

 ratus giving way when they peck at it There is a small orifice 

 at each end of the egg-shaped bag, to admit of the escape of the 

 moth, when it changes from the little chrysalis which sleeps 

 tranquilly in its airy cage. The moth is of a dull slaty colour, 

 and belongs to the Lithosiidffi group of the silkworm family 

 {BomiyddiB). 



When the caterpillar begins its work, it lets itself down from 

 the tip of the leaf which it has chosen, by spinning a thread of 

 silk, the thickness of which it slowly increases as it descends. 

 Having given the proper length to the cord, it proceeds to weave 

 its elegant bag, placing itself in the centre, and spinning rings 

 of silk at regular intervals, connecting them at the same time by 



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