. Lessons in nature study. Nature study. POND INSHCTS 73 while the back-swimmers (fig. 44) have the back bhi- ish black with large creamy white patches. Both kinds come to the surface to get air, the water-boatmen very much more rarely than the back-swimmers. The water-bugs,like the water-beetles, carry down with them into the water a supply of air held on the outside 01 the body. The air clings to a large part of the body lying both under the folded wings and ou the exposed surface of the body. Note the difference in the disposition of the air in the two kinds of bugs. Is there a difference i
. Lessons in nature study. Nature study. POND INSHCTS 73 while the back-swimmers (fig. 44) have the back bhi- ish black with large creamy white patches. Both kinds come to the surface to get air, the water-boatmen very much more rarely than the back-swimmers. The water-bugs,like the water-beetles, carry down with them into the water a supply of air held on the outside 01 the body. The air clings to a large part of the body lying both under the folded wings and ou the exposed surface of the body. Note the difference in the disposition of the air in the two kinds of bugs. Is there a difference in their weight as com- pared with the weight of water ? What part of the body projects above the surface when the bug comes up for air ? Note the cus- tomary position of the body and legs as one of the back-swimmers lies at rest just underneath the surface with the tip of the abdomen projecting very slightly above it. Which pair of legs is the row- ing pair ? Throw some non-swimming insects, as house-flies, in- to the water and observe the actions of the back-swimmers with regard to them. Kill a few back-swimmers in the cyanide bottle and examine them. Note,that altho they are aquatic insects,they have wings; they are thus able to fly from pond to pond. Note the oar-like character of the swim- ming legs; note their broad fringes of hair. Note the sharp-pointed strong beak which the back- swimmer thrusts into the bodies of its prey, and thru which the blood of the captured insect is sucked. Care must be exer- cised in handling live back-swimmers, as they can inflict a pain- ful sting with the sharp beak. Note that the water-boatmen keep usually to the bottom of the aquarium, coming only rarely to the surface lor air. Note their favorite resting position. In what way does this differ from. e«^^ Fig. 4B. A Water-boatman (Cofisa).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance
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