POND LIFE. II9 



be able to observe that in some species there are two 

 kinds of females, one bavins: smooth winer-covers, 



o o 



and another in which the \vins:-cov- 



O 



ers are furnished with a number of 

 deep furrows (Fig. 94). 



8. Study the eyes and compare 

 them with those of the whirlis:is:- 



o o 



beetles. 



. FIG. 96. 



9. Remove one wing-cover and 



observe the large wing folded beneath it. These 

 beetles can fly well, and thus migrate from pond to 

 pond. 



10. Remove the wing and observe the spiracles 

 or breathing holes on the back near the side of the 

 body. 



11. How do these insects breathe when under 

 water ? 



THE HABITS AND STRUCTURE OF THE PKEDA- 

 CEOUS DIVING-BEETLES (School Work\.~- Write an ac- 

 count of what you have learned regarding these in- 

 sects. 



THE WATER-TIGERS (Field and School Work)- 

 These rapacious creatures are the larvse of the pre- 

 daceous diving-beetles, and are found in the ponds 

 frequented by these beetles. In sweeping submerged 

 plants for the pond insects already described one is 

 quite apt to obtain water -tigers also. They are 

 elongated, spindle-form grubs, with large sickle- 

 shaped mandibles. Fig. 97 represents one of our 

 larger species. Put the specimens that you collect 

 into an aquarium in which plants are growing, so 

 that the larvce can crawl to and from the surface 

 easily. 



