ON THE TRANSFORMATION OF INSECTS. 19 



on the back ; the insect emerges and flies away, leaving that 

 one skin only : that beautifully delicate skin which the 

 dragon-fly quits simultaneously with the harder one, being still 

 retained by the May-fly. Here then we have the strange 

 fact of an insect's flying before it reaches the imago ; that is, 

 flying in its penultimate state. In twenty or thirty minutes at 

 the farthest it settles again, casts its skin, and becomes a 

 perfect imago. 



It thus appears, that, although until the final ecdysis, no 

 insect arrives at perfection ; yet before that period, even in the 

 state immediately preceding, it may feed, run, and even fly; 

 or may swim, crawl, barely move, or be without motion, with- 

 out apparent life, or without apparent organization. It appears 

 that the apparently lifeless or quiescent state may be entered 

 without ecdysis ; that ecdysis itself may be either single or 

 double; that the states called pupa, in various tribes, are 

 neither substantially nor numerically the same. That com- 

 paring those few insects herein noticed, the fly, the bee, the 

 cricket, the dragon-fly, and the May-fly, all of which represent 

 great orders, we shall find it perfectly impossible to apply, if 

 we aim at precision, any other than a numerical denomination 

 to their intermediate states ; and finally, therefore, that insects, 

 like higher animals, have but three eras of existence, the fcetal, 

 the adolescent, and the adult. 



As to the number of times ecdysis takes place in the life of 

 an insect, little can be said at present, owing to the careless- 

 ness and imperfection of our researches ; and on this account 

 it will be found safer to count downwards from the imago, 

 than upwards from the eggs. Although the contrary has 

 been asserted, and perhaps generally believed, it yet remains 

 to be proved that the grubs of Diptera and aculeate Hymen- 

 opt era, undergo any ecdysis until full grown. The order 

 Tenthredinites, on the contrary, and the Lepidoptera, change 

 very frequently, with some exceptions ; for example, the 

 caterpillar of the great Sphinx Ligustri sheds its skin but 

 once. 



These various facts, so simple, so obvious, so plain, so com- 

 pletely within the reach of the most cursory observer, proclaim 

 that each variation in the number or manner of ecdysis is but 

 another mode of metamorphosis ; proclaim that metamorphosis, 

 hough in annulates, a complete and oft-repeated ecdysis, is but 



