334 INSECT TRANSFORMATIONS. 



much 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 trans- 

 formation of the ant-lion {Mijrmeleon formicarium,) 

 whose singular 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 cocoon 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 outside, 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-lly makes use of its mandibles to 

 gnaw the cocoon. When it has arrived on the out- 

 side it only requires to expand its wings and body to 

 complete its transformation. .But this is the process 

 most calculated 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, &o. 



