CHAPTER l 



AQUATIC BEETLES 



THE WHIRLIGIG BEETLE (GvRiNus) 1 



GYRINUS, also called the Whirligig Beetle or Steel- 

 coat, is a small blue-black Beetle, about a quarter of 

 an inch long, which abounds on the surface of still 

 streams. It is sometimes seen disporting itself on 

 a clear pond or small puddle, but it prefers gently 

 running water. During the summer months, the 

 Whirligigs congregate in swarms, darting swiftly to 

 and fro like Swallows or Bats with movements so 

 rapid that the eye can scarcely follow them. Now 

 and then, especially when alarmed, they dive to the 

 bottom of the water, or swim about beneath the 

 surface. When they descend, they carry with them 

 a bubble of air attached to the hinder end of the 

 body, which glitters like quicksilver. They may be 

 often seen clinging to submerged weeds, but as soon 

 as all is still again they let go their hold, rise without 

 effort to the surface, and resume their gyrations. It 



1 I have to thank Mr. W. F. Baker for some useful observa- 

 tions on this Insect. 



