6o 



SOME WATER INSECTS. 



We may roughly divide water insects, from our point of view, 

 into two groups, (a) insects which live in running water, in brooks, 

 and (6) insects which live in quiet or stagnant water, in ponds. 

 We may observe water insects in their homes, i. e., in the brook 

 and in the pond, and we may bring them alive into the school- 

 room and watch them there. To do this we need aquaria. To 

 keep the brook insects alive long enough to observe their habits 

 and transformations we shall require a running water aquarium, 

 which only a few school-rooms are in position to have. But the 

 quiet or stagnant water aquarium can be easily made and main- 

 tained in any school-room. (For directions for making and caring 

 for aquaria, see the earlier lesson on "Rearing Insects." ) Our 

 observation of water insects may be divided into field work and 

 school-room work ; that is, observation of insects in the brooks 

 and ponds, and observation of them in the school-room aquaria. 

 Most of the observing of brook insects must be field work ; while 

 most of the observing of pond insects can be done in the school- 

 room. 



Brook Insects. 



YouxG StoxE- FLIES AND May-fi,ies. Find a place where the 

 brook is shallow and running quickly, and has a stony bottom. 

 Examine the under side of a number of the stones of the bottom 

 and you will almost certainly find on them certain flattened in- 

 sects from half an inch to an inch in length, which run quickly 

 and attempt to hide in the inequalities of the stone. Note that 

 altho these insects live in the water they do not, like many 

 water animals, have fius, but they have three pairs of legs with 

 which they can either run about on the stones or swim in the 



