334 INSECT TRANSFORMATIONS. 



increased that birds of large size can dart down from 

 great heights in the air with astonishing velocity. 



In insects a similar mechanism occurs, though it 

 is more difficult to trace it, on account of the great 

 minuteness of the several organs; but so far as the 

 circumstances can be observed, they well merit our 

 attention. The most remarkable of these is the 

 expansion of the body and wings on the perfect 

 insect emerging from the pupa case. A very striking 

 exemplification of this occurs in the transformation of 

 the ant-lion (JS'Iyrmcleon formicarium), whose sin- 

 gular stratagems in the grub state are so familiar 

 to the readers of books on natural history.* When 

 it is about to change into a pupa it constructs a co- 

 coon of sand, which it lines with a beautiful tapestry 

 of silk, the whole being less than half an inch in 

 diameter, the pupa itself, when rolled up, filling 

 only a space of about half this dimension. When 

 it has remained in the cocoon about three weeks, it 

 breaks through the envelope and emerges to the out- 

 side, as the chrysalides of wood-borers make their way 

 to the exterior of a tree to facilitate the exit of the 

 perfect insect ; with this difference, that the nascent 

 myrmeleon-fly makes use of its mandibles to gnaw 

 the cocoon. When it has arrived on the outside it 

 only requires to expand its wings and body to complete 

 its transformation. But this is the process most cal- 

 culated to excite our admiration ; for though it is not 

 on its emergence more than half an inch in length, it 

 almost instantaneously stretches out to an inch and a 

 quarter, while its wings, which did not exceed the 

 sixth of an inch, acquire an immediate expansion of 

 nearly three inches. 



To the real wonders attending the history of this 

 remarkable insect, it has been fancifully added, that, 

 as it has cast off the spoils and cumbersome weight 

 "See " Insect Architecture,"" page 209, &c. 



