^ 



POND LIFE. Ill 



5. Study all the specimens you have of water- 

 striders and see if you can separate the sexes. 



The Whirligig-beetles {Fie/d Work). — No lad 

 who has loitered much by ponds or wandered along 

 the margins of brooks with open eyes can have 

 failed to see the whirligig-beetles, those social fel- 

 lows that gather in large numbers and chase each 

 other round and round in graceful curves with 

 wonderful rapidity. These beetles are oval or ellip- 

 tical in form, more or less flattened, and usually of 

 a very brilliant, bluish-black color above, with a 

 metallic luster; one of our common forms is 

 represented by Fig. 90, but some of the smal- 

 ler species are proportionally longer and more 

 convex. 



Seek for specimens of whirligig-beetles on 

 the surface of the ponds and streams in your 

 locality and, when found, watch them carefully, note- 

 book in hand, and record all that you can see of their 

 ways. 



Take with you on this field trip some empty bot- 

 tles, in which to bring home living specimens, and an 

 insect net ; you will need the latter in catching these 

 wary creatures. 



Note the peculiar odor emitted by the insects 

 when caught ; this is caused by the milky fluid which 

 the insects emit from various joints of the body, and 

 is probably a means of defense. 



As these insects can be easily kept alive in aquaria, 

 we will make a more careful study of their habits in 

 confinement. 



Comparatively few whirligig-beetles can be found 

 in the spring ; these are individuals that have sur- 



