THE BACK SIVIMMERS 



(Family Notonectidce.) 



These water bugs known as the " back swimmers " much 

 resemble the water boatmen, but are very convex on the 

 back and always swim with the belly upwards. This, in fact, 

 distinguishes them from all other water bugs. In their habits they 

 are much like the water boatmen. They are predaceous, and 

 feed upon other water insects and even fish. They are strong 



enough to master 

 a good-sized min- 

 now, and a prick 

 from their beak is 

 as painful as a bee 



i^Wtf^df "^ I HHH sting. They carry 

 ^SM jf^^^^^^ SHi below with them a 

 ^Sw ^m ^^p^ greaterair 111m than 



^ ^^ do the others, and 



^ have to hold fast 



with their fore legs 

 to some stone or 

 water plant to prevent themselves from popping up to the surface. 

 They are most active insects, and most interesting creatures for 

 the aquarium. They hibernate in the mud at the bottom of 

 streams, pools and ponds. The eggs are laid in the stems of 

 water plants, which are pierced by the sharp ovipositor of the 

 female. About two-thirds of the egg are pushed into the 

 incision, and the remaining third is left extruding. 



About a dozen species are known to inhabit the United 

 States, and these are distributed in the genera Noionecta, Anisops 

 and Plea. 



A good life history of one of our common species such as 

 Noionecta undulata, widely distributed in North America, is still 

 to be written, but could be made out in any school aquarium. 



275 



Fig. 16S. — Notonecta undulata Say : upper and 

 lower side, beak and leg. (After Lugger.) 



