ANT-LION'S COCOON. 245 



Enough of the ant-lion grub, as the pattern in its opera- 

 tions of our ogre's method of attack ; but to unravel the 

 mystery of the ogre's magic ball, and of the winged " genius" 

 thence proceeding, we must glance at the Formica Leo in its 

 transformations. 



A popular writer thus describes them : " When the ant- 

 lion grub 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 

 outside making use of its mandibles to gnaw the cocoon. 

 It then 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."* 



This wondrous process of expansion is exemplified scarcely 

 less remarkably in our lace-wing fly. The construction of 

 pitfall traps, and the pelting of victims into them, is an artifice 

 not entirely confined to the grub of the ant-lion, that of a 

 fly* being said, among others, to adopt them. The practice 



* See Vignette. 



