FIELD BOOK OF PONDS AND STREAMS 



insects and snails and the young of many water animals are 

 abundant (Fig. 22). The}^ are active from very early spring, 

 beginning to appear in the water as soon as the ice leaves the 

 shore; some lay their eggs by the middle of April. Their 

 activity goes on till late fall or early winter, depending 

 upon the season. With a few exceptions they hibernate as 

 adults. They gather for the winter in matted branches of 

 Chara, and skulk in the trash beneath banks. They are long- 

 lived, often surviving for a year or more. 



Food. — ]Many water-bugs attack any animals which they 

 can manage, large or small. Their larger prey includes young 

 fish, snails, and dragonflies, but they also devour great num- 

 bers of small crustaceans, mosquito larvse, midge lan^as, and 

 insects which fall into the water from overhanging foliage. 

 But the water boatmen are mainly herbivorous, gathering 

 their food from the bottom ooze which consists largely of 

 algae and decaying plants. They not only maintain their 

 own numbers but they furnish part of the food for their 

 cannibalistic relatives. 



Associates. — Water-bugs occupy the surface of the shallows 

 with whirligig beetles, springtails, and pond-snails. Water- 

 bugs and crayfishes are sometimes associated through a 

 peculiar habit of the water boatman, Ramphocorixa acuminata, 

 which lays its eggs upon crayfishes. The performance has 

 been fully described in a paper by J. F. Abbot with photo- 

 graphs of crayfishes laden with eggs of the water-bugs. Many 

 crayfishes have since been studied in eastern Kansas by 

 Hungerford who believes that the eggs are placed on the 

 regions of the crayfish (Cambarus imniunis) where they have 

 the best chances of aeration by currents of water from the gills. 

 The female of another water-bug, Belostoma, places her eggs 

 on the back of the male of her own species (Fig. 175), but the 

 crayfish carries the boatman's eggs just as safely and takes 

 the burden entirely off the family. 



Aquarium study. — Water-bugs can be kept in aquaria for 



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