THE BACK-SWIMMER. 61 



Get an exuvia of a cicada, and study it carefully. Do 

 not fail to note how completely 

 the hard, external skeleton, 

 together with its internal pro- 

 jections, is shed. Compare it 

 with the adult in form and rela- 

 tive development of locomotive 



organs. NYMPH OF HARVEST FLY. 



THE BACK-SWIMMER. 



(Notonecta.) 



Haunts and Habits. This insect is abundant in the 

 pools of brooks and in ponds. It is a little over half an 

 inch in length. It may readily be recognized by its in- 

 verted position in the water. It swims on its back, and 

 rests with its wing tips just touch- 

 ing the surface of the water, and its 

 long hind legs poised forward and ex- 

 tended on either side. When startled, 

 it darts away toward the bottom : but it 

 BACK-SWIMMER, NO- wi U rise again immediately when it stops 



tonecta (slightly swimming-, unless it holds to some sub- 

 enlarged). , , , 



merged object; for its body, together 

 with the air inclosed beneath its wings and between its 

 thoracic segments, is much lighter than the water. 



Back-swimmers are easily taken in a net. All stages 

 will be found together. They may be kept at home in a 

 bowl of water, and their habits studied. Care should 

 be exercised in handling them, for they will sometimes 

 inflict wounds with their sharp and strong rostrum. 

 When it is necessary to take one alive with the fingers, it 

 may safely be picked up by the sides of the body. Back- 

 ris present many interesting adaptations to aquatic 



