Il6 INSECT LIFE. 



After learning what you can by watching, sweep 

 the vegetation beneath the surface of the water with 

 your net, and in this way collect as many kinds of 

 insects as possible. Put the insects into clean bot- 

 tles so that they may be kept alive. 



On your return prepare several aquaria with sand 

 or gravel on the bottom and aquatic plants anchored 

 in the sand ; if practicable prepare as many aquaria 

 as you have kinds of insects, so that one kind shall 

 not destroy another. But in order to observe pre- 

 daceous insects capture their prey it is necessary to 

 put other insects with them when you are ready to 

 make the observation. After the insects have been 

 placed in the aquaria you will soon be able to learn 

 which ones belong to the class that rest at the surface 

 but swim beneath. 



The Predaceous Diving-beetles {School Work). 

 — If a collecting trip like that outlined above is a 

 successful one, there are almost sure to be several 

 kinds of beetles among the insects collected. These 

 can be recognized by the horny wing-covers, which 

 meet in a straight line along the middle of the back. 

 If we omit certain small beetles which are not likely 

 to be studied by the beginner, the beetles collected 

 in this way will represent only two families ; one of 

 these families is the Dytiscidae, or predaceous diving- 

 beetles. The members of this family can be recog- 

 nized by the fact that when at rest they hang head 

 downward with the tip of the abdomen at the sur- 

 face of the water. Figs. 93 and 94 represent two of 

 the larger members of this family. There are, how- 

 ever, many small species, measuring less than one 

 fourth of an inch in length, which can be found in 



