132 



DIPTERA. 



FIG. 136. LARVA OF STRATVO.MYS. 



they breathe. The skin of the larva is not cast off, but becomes the cocoon 

 of the pupa, simply growing stiff and angular. In this condition it may be 

 found floating on the water. When the perfect insect is complete, it escapes 

 through a fissure in the second segment, and after cruising about for a little 

 time, supported by its old integument so as to allow its wings to dry, it takes 

 flight. 



FIG. 137. WASP-FLIES. 



The Wasp Plies (Eristalts\ everywhere to be seen on a hot day, hover- 

 ing before the flowers in our gardens, and darting here and there with sudden 



