242 INSECT WATEE TRESPASSERS. 



that even the shadow of a passing bird or butterfly 

 will send them below. 



If the approach has been properly made, the surface 

 of the water will be seen to be thickly studded with 

 these beetles, all lying motionless, and apparently 

 enjoying the warm sunbeams. The multitude of these 

 insects which will find room in a small pond must be 

 seen to be believed. A casual passenger will scarcely 

 know that there is a single beetle in the pond, for his 

 approach will have sent them all below, the only 

 aquatic insects visible being the whirlwigs and the 

 water gnats, who seem to be incapable of fear, and 

 traverse the surface of the water as freely as if no 

 intruder were near. 



There is a little pond near my house which admi- 

 rably illustrates the habits of these insects. On a fine 

 day, the whole surface is covered thickly with these 

 creatures, scarcely any of them descending, but others 

 ascending in all parts of the pond, and immediately 

 floating motionless at the top. Then, if the spectator 

 but raises an arm, all is flurry and confusion, and the 

 water is filled with the rapidly descending insects. A 

 few moments more, and except the whirlwigs and 

 water gnats, there is not a sign of life in the pond. 



The Water Beetles, of which the Great Water Beetle 

 is a type, are very numerous, and vary greatly in 

 size j some measuring a full inch in length, while 

 others are scarcely the eighth of an inch long. 



They are all predacious creatures, finding their 

 food chiefly among the larvae of the various water 

 insects. They are not at all fastidious as to the pecu- 

 liar food which they eat ; and have no hesitation in 



