FIELD BOOK OF PONDS AND STREAMS 



distributed all over the United States. Length of adult, one 

 half inch. 



Fig. i8i. — A slender backswimmer, Btienoa mar- 

 garitacea, with front and middle legs folded. 



Buenoa margaritacea. — This genus (Fig. i8i) includes a few 

 slender backswimmers which have the habit of swimming and 

 hanging in mid- water. The wings are moonlight white ; there 

 is a flush of pink on the back of the thorax and the underside 

 of the abdomen is deep red. Hungerford could not discover 

 their eggs in ponds but from the shape of the ovipositor de- 

 cided that they were laid in plants. When smart-weed stems 

 were put in the aquarium with them the females promptly 

 riddled them with eggs. 



They live upon small crustaceans which they hold while they 

 feed upon them in a sort of cage made by the bristles of their 

 first four legs. Length of adult, one quarter of an inch. 



Creeping water-bugs, Family Naucoridae. — These are broad, 

 thick-set bugs of moderate size in which the hind legs are not 

 flattened for svv-imming as they are in the backswimmers and 

 water boatmen but the front femora are greatly thickened 

 (Fig. 182). They creep about on the stems in quiet water 

 which is densely grown with vegetation. They bite or "sting" 

 on the slightest provocation. 



1 



Fig. 182. — Creeping water-bugs: i, Pelocorisfemo- 

 ratns; 2, the pigmy water-bug, Plea striola. 



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