STATES OF INSECTS. 219 



the rest of the cocoon, so that the point of union is always 

 discoverable. These caterpillars do not always divide 

 the cocoon into two equal portions, for often they will 

 finish three quarters of the cocoon before they enter it, 

 and begin at the other end a . 



The general rule is, — that each larva spins for itself a 

 separate cocoon ; but amongst those of Arctia chrysorhea 

 and others which live in society, two or three sometimes 

 begin their operations so close together that they are 

 under the necessity of forming one common cocoon, which 

 serves for a covering to the whole number. The same 

 thing happens to silk- worms, the double or treble cocoons 

 of which are called Dupions by the breeders. The larvae 

 of some Ichneumons, besides forming each its separate 

 cocoon, spin a joint cottony covering for the whole 5 , 

 which is effected thus: — After they leave the caterpillar 

 they have devoured, they fix themselves side by side at a 

 little distance from it, and begin to spin each a cocoon ; 

 and in order to defend its end and side that is not covered 

 by others, they spin further an envelope of loose silk, 

 and thus this exterior covering is formed. 



The size, figure, colour, substance, and texture of 

 silken cocoons are extremely various. Their size indeed 

 is usually proportioned to that of the included larva or 

 pupa ; yet it is by no means always so. Some large ca- 

 terpillars spin cocoons so small, that the observer can 

 hardly conceive how they can be contained in so narrow 

 a compass : Eriogaster Cataoc is a moth of this descrip- 

 tion c . And others smaller in size lodge themselves in 



a De Geer i. 463—. 



b Reaum. ii. Mem. xi. Comp. De Geer ii. 162. Reaum. ii. 424. 



e JB. Catax — Pupa arete folliculata. Fab. 



