78 DIPTERA. 



in this Order of insects, and which would alone 

 distinguish it from every other. It is the poiser, 

 or balancer ; a little ball fixed to the end of a 

 slender stem, which is itself attached under the 

 origin of each wing. It seems a provision of 

 Nature to compensate for the want of the se- 

 cond pair of wings, and by its quick and lively 

 action, while the insect is in flight, to keep the 

 body in a due state of equilibrium. It is to the 

 dipterous insect, what the loaded pole is to the 

 rope dancer. In the Tipulse, and Culices, these 

 balances are large and apparent ; in other ge- 

 nera they are small and concealed. 



