CH. XXII.] METAMORPHOSES OF INSECTS. 295 



of inactivity occurs during the time in which the 

 insect undergoes its pupa state, although, as we 

 shall subsequently notice, there are certain insects 

 in which it is only during a portion of the time oc- 

 cupied in this stage that this inactivity continues. 

 Thus, in the caddice-flies, composing the order 

 Trichoptera, Mr. Kirby has pointed out the curious 

 circumstance, that, shortly before the insect throws 

 off its pupa skin in order to appear as a winged fly, 

 it is endowed with activity, its legs are put in mo- 

 tion, and, by the assistance of a pair of curious 

 hooks on the head, the meshes of the net, which it 

 had, previous to becoming a pupa, spun at the 

 mouth of its cage, are cut ; the object of which is 

 very evident, since, were such not the case, the in- 

 sect could not be able to join its brethren in their 

 mystic dances in the air ; the larva being aquatic, 

 it is requisite that, previous to throwing off the 

 pupa skin and appearing in the winged state, the 

 insect should quit its former native element, and 

 make its way into one which will be better suited 

 to its future state. 



The next variation of metamorphosis (to which 

 indeed the Trichoptera are in strictness referrible), 

 is generally termed incomplete, and comprises a far 

 greater number of insects than any of the other 

 kinds, the body of the pupa being covered with a 

 thin skin, having the various organs, as the legs, 

 wings, antennas, &c., enclosed in separate sheaths, 

 which are laid along the breast during the inactive 

 pupa state, and from which the insect, on arriving 

 at the perfect state, draws out its limbs, just as we 

 do our fingers from a glove ; these limbs are, con- 

 sequently, not so closely applied or fixed to the 

 body as in the true chrysalides, and they therefore 

 allow the form of the various parts to be easily ob- 

 served. The numerous tribes of beetles (order 

 Coleoptera), bees, wasps, sawflies, &c. (order Hy- 

 menoptera), ant-lion-flies {Myrmeleomd(B), golden- 



