STATES OF INSECTS. 215 



Geometrce (G. papilioniaria, lactearia, &c); most of the 

 Hymenoptera ; some Coleoptera, as certain of the weevil 

 tribe (Hyper a Arator, Rumicis Germ.), and those bril- 

 liant beetles frequenting aquatic plants constituting the 

 genus Donacia F. ; the Neuropterous genera Hemerobius 

 and Myrmeleon : Mycetophila and a few others in the 

 Diptera ; and Pulex in the Aphaniptera fabricate cover- 

 ings of the same material. In all, with the exception of 

 Myrmeleon and Hemerobius (and perhaps Hypera Rumi- 

 cis, &c. ?) which have their spinning apparatus at the 

 extremity of the abdomen, the silken thread employed in 

 forming these coverings proceeds from the middle part of 

 the under-lip, as before explained ; and is in fact com- 

 posed of two threads gummed together as they issue from 

 the two adjoining orifices of the spinner. 



Of the larvas which inclose themselves in silk, the most 

 familiarly known is the silk-worm : the cocoon of this 

 consists exteriorly of a thin, transparent, gauze-like coat- 

 ing, through the interstices of which can be seen an in- 

 ner, smaller, oval ball of a more close and compact tex- 

 ture. The whole is in fact composed of one single 

 thread, but arranged in two distinct modes. To form 

 the exterior envelope, which is merely the scaffolding by 

 means of which the inner and more solid covering is con- 

 structed, the caterpillar, after fixing upon a space between 

 two leaves or twigs or angles suitable for its purpose, 

 begins by glueing one end of its thread to one of the ad- 

 joining surfaces. This thread it next conducts to another 

 part and then fastens, repeating this process and inter- 

 lacing it in various directions, until it has surrounded it- 

 self with a slight and loosely spun netting. In the cen- 

 tre of this, when contracted into a space sufficiently small, 



