POND LIFE. 



115 



there is some difference of opinion among scientific 

 writers on this point. 



After observing these insects at intervals for sev- 

 eral days write an account of what you have learned 

 regarding them. 



INSECTS THAT REST AT THE SURFACE BUT SWIM BENEATH. 



In our studies of pond life up to this time we 

 have observed some of the insects that fly over 

 ponds and some that live upon the surface of water, 

 but a far greater number of insects live within 

 the water. Some of these are fitted for a purely 

 aquatic life, but many find it necessary to come to 

 the surface from time to time to get a supply of air. 

 This latter class of insects, as a rule, rest at the sur- 

 face in such a position that they have access to the 

 air above the water, and only swim beneath when 

 alarmed or when in search of food. It is this class of 

 insects, those that rest at the surface but swim be- 

 neath, that we are to study now. 



A Collecting Trip. — Provide yourselves with 

 insect nets and a supply of empty bottles for bring- 

 ing back living insects. Go to some pond or stream, 

 and, resting quietly on the shore, try to observe some 

 of the insects that live within the water but rest at 

 the surface. If there is no convenient pond and you 

 go to a stream for this purpose, choose the more 

 quiet portions of the stream, and preferably the 

 deeper pools and those in which plants are growing. 

 Approach the water very quietly so as not to frighten 

 the insects. Often when nothing is to be seen at 

 first the observer will be rewarded by a sight of 

 the desired objects if he will sit very still for a time. 



