1050 FAMILY XXXIX. — NOTONECTID^E. 



bb. Elytra glabrous, subhyaline; last antennal longer than the one 



preceding; scutellum little if any more than half the length of 



claval commissure. II. Buenoa, p. 1056. 



mi. Legs of equal length, the hind tibia? and tarsi without a fringe of 



hairs; abdomen not keeled or hairy; eyes small, widely separated; 



length less than 3 mm. (Subfamily Pleinse) . III. Plea, p. 1060. 



I. Notonecta Linnaeus, 1758, 439. 



This genus comprises our most common and best known 

 species of the family. They possess the characters given under 

 the family heading and in the key and have the antennae and 

 beak 4-jointed ; front margin of pronotum truncate ; proster- 

 num short, front legs inserted close to its hind margin; middle 

 femora not received in grooves on the mesosternum ; hind 

 femora not reaching the apex of elytra. Eight of the 13 known 

 North American species occur in the eastern states. Of their 

 habits Bueno (1905a, 146) says: 



"They are exceedingly active and fiercely predaceous resembling 

 nothing so much as hawks among the vertebrates. Their principal prey 

 are such unfortunate insects as fall into the water within the ken of the 

 watchful water-bug, or such of the feebler aquatic insects as they can 

 overcome, not disdaining their own young. From their position, hanging 

 back down at or near the surface, nothing escapes them and at the 

 slightest vibration imparted to the water by any struggling insect, or 

 the least motion of one swimming by, they wheel swiftly about and with 

 one or two powerful strokes of their long swimming legs are on their 

 prey and have it seized in their strong first and second pairs of legs." 



He states that the nymphs have been seen to attack and 

 swim away with a young fish twice their size and that they 

 "will eventually be found to be of positive economic impor- 

 tance not only as an enemy in fish culture, but possibly also in 

 useful ways by the destruction of undesirable aquatic larvae." 

 The eggs are attached to the stems or leaves of aquatic plants, 

 hatch in 20 to 30 days, and the adults hibernate in the mud or 

 muck at the bottom of the pools which they inhabit. 



KEY TO EASTERN SPECIES OF XOTOXECTA. 



a. Larger species, length 12 or more mm. 

 b. Greatest width of interocular area (on front of head) three times 

 that of narrowest point near base of head (fig. 212) ; general 

 color black or dark brown mottled with paler. 1188. irrorata. 



bb. Greatest width of interocular area not over twice that of the nar- 

 rowest point; general color white or dull yellow, often with black 

 markings. 



