THE BUGS: HEMIPTERA 



31 



is taken into a cavity under the wings, where the spiracles 

 are placed, so that quite a supply is on hand at all times. 

 While these insects are thus adapted to water-life, they can 

 fly, and often leave their native ele- 

 ment, especially if it is in danger 

 of becoming dry. 



Another widely distributed 

 group of insects resembling the 

 foregoing are the back-swimmers 

 (Notonec'ta, Fig. 16, 

 A, A'), which have 

 the curious habit ' 

 of swimming on 

 their backs, as 

 their common arid scientific 

 names denote. A favorite posi- 

 tion of these insects is to float with the 

 head down and the tip of the abdomen 

 protruding just enough to admit the 

 passage of air to chambers beneath the 

 wing-covers. The back-swimmers can 

 inflict a momentarily painful wound 



with their sharp beaks. Search made 



. . FIG. 17. Squash-Bug and 



for these insects will reveal a variety of Young. Natural size 



other beaked forms, some of which live 



beneath the surface of water, while others skim swiftly over it. 

 Plant-Bugs. The squash-bug (An'asa tris'tis, Fig. 17), a 

 well-known enemy of squash and pumpkin vines, also pos- 

 sesses a beak, which is used to suck plant instead of animal 

 fluids. This bug is a little over two centimeters (nearly an 

 inch) long, and brownish black in color. It has the power, 

 in common with many other allied species, of pouring out an 

 evil-smelling secretion from two openings near the base of 

 the middle pair of legs, which probably renders it obnoxious 



