HEMIPTERA 



365 



Although the Nepidae are aquatic insects, the second and third 

 pairs of legs are fitted for walking rather than for swimming. 



Of the genus Nepa we have only a single species, Nepa apiculdta. 

 This insect is about i6 mm. in length, not 

 including the respiratory tube, which 

 measures a little more than 6 mm. It 

 lives in shallow water concealed in the 

 mud or among the dead leaves and twigs, 

 lying in wait for its prey. The eggs are 

 inserted in the tissues of decaying plants ; 

 they are an elongate oval and bear near 

 one end a crown of eleven slender fila- 

 ments. 



Of the genus Rdnatra eight American 

 species have been described. These in- 

 sects are found in the same situations as 

 Nepa; where, owing to the linear form of 

 the body and to the dirt with which it is 

 usually covered, it is quite difficult to de- 

 tect their presence. They have also been 

 observed in deep water clinging to the 

 stems of rushes and grasses, with the re- 

 spiratory tube piercing the surface film 

 (Bueno) ; and also upon floating dead 

 leaves and stalks of cat-tail, where the}' 

 were basking in the sun and entirely dry 

 (Hungerford). 



Ranatra has stridulating organs; these consist of a roughened 

 patch on the outside of each fore coxa and a rasp on the inner margin 

 of each shoulder of the prothorax ; b}' means of these organs a squeak- 

 ing sound is produced. 



The eggs of Ranatra have been described by Pettit; they are 

 elongate oval, about 3.5 mm. in length, and bear at one end a pair of 

 slender appendages, about 4 mm. long; they are embedded in the 

 rotting stems of aquatic plants, from which the appendages of the 

 eggs project. 



A monograph of the Nepidfe of North America was published by 

 Himgerford ('22). 



Fig. 418. — Ranatra ftisca. 



Family BELOSTOMATID^ 

 The Giant Water-Bugs 



The common name "giant water-bugs" was applied to this family 

 because to it belong the largest of the Hemiptera now living; a 

 species that is found in Guiana and Brazil measures from 75 to 100 

 mm. in length; and the larger of our species exceed in s^'ze our other 

 water-bugs. 



