FLIES. 135 



out its extensile body, to seize the nearest, and 

 extract the honey-dew. After it has drank its fill 

 and grown to full size, it suddenly wraps itself up 

 in a blanket of glutinous secretion, and in a pupal 

 state, goes to sleep on the same leaf or stem from 

 which it has fed. 



The eggs of many of the diptera are hidden 

 away in toad-stools, decayed wood, moss and the 

 like. Some are deposited in the water, and the 

 maggots have curious devices by which they 

 breathe the air. 



A gaily-uniformed fly, with spined shield, a 

 green coat, spotted and banded with black, yellow 

 legs and purple eyes, searches the shores of ponds 

 and slowly-running streams, and fastens its eggs 

 on the aquatic plants. In due time the little foot- 

 less grub is launched into the world of waters, and 

 by the aid of a bubble, which it forms at the 

 breathing pore by means of a whorl of bearded 

 hairs, is kept afloat ; or if it sinks, it carries with 

 it this supply of air, from which to draw while 

 beneath the surface. Here it feeds on the prey 

 that comes within its reach, until it has grown to 

 the full measure of maggothood. As it assumes 

 its pupal character, it gradually decreases in bulk, 

 till at last it is so contracted that it occupies half 

 of its larval skin only, which it now uses as a boat 

 and sails about on an aimless voyage, waiting for 

 the sunny days when it shall cast away its swad- 



