CHAPTER XVIII 



INSECTS IN THE WATER 



Although insects are essentially creatures of the earth 

 and air, many species have adopted an aquatic life. Yet 

 no hard-and-fast line can be drawn between water insects 

 and their terrestrial kindred, for many larvae feed habitu- 

 ally in semi-liquid mire, or in water-logged soil, while 

 large numbers of insects, notably beetles, frequent marshy 

 spots, and are equally at home upon land or in the water. 



So far as is known, no insect remains submerged 

 throughout the whole of its life. Numerous bugs 

 (Heteroptera) frequent water in all the stages of their 

 existence, but they breathe atmospheric air, and drown 

 quickly if they are kept forcibly below the surface. 

 Many of them — e.g. the water boatmen (Notonectidce) — 

 have well-developed wings in the adult state, and fly 

 freely from one pond or lake to another, especially after 

 nightfall. The familiar pond-skaters and their allies 

 (Ilydromctridce), which glide over the surface of stagnant 

 pools and sluggish streams, make frequent excursions 

 among the herbage of the banks. Indeed, they really 

 walk upon the water — or rather upon the elastic surface- 

 film where air and water meet. Their body and legs are 

 covered with minute hairs, which tend to retard moisture ; 

 and they may frequently be seen lifting their legs into 

 the air to dry them. If their feet become wet, they sink 

 through the surface- film. 



Another interesting group of surface-dwellers consists 

 of the whirligig beetles (Gyrinidoe), whqse middle and 



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