hungerford: aquatic hemiptera. 29 



shore. Two row over the open waters, and five lead a sub- 

 aquatic life. The first eight are called semiaquatic, the last 

 five true aquatics. The general distribution of these forms is 

 shown in the synoptic table. There are some exceptions, and 

 some structural details have been added to identify genera, so 

 that the table cannot be called purely ecological. 



HABITAT KEY TO THE AQUATIC AND SEMIAQUATIC HETEROPTERA. 



A. Upon the shore; not running out upon the water, although they 

 may alight there. 



B. Escape by quick jumps and short flights. Antennae 

 longer than the head. Saldidse. 



BB. Escape by hopping, flying or concealment. Antennae 

 shorter than the head. 



C. Beak very short. Gelastocoridse. 



CC. Beak longer. Ochteridse. 



AA. At the water's edge, running out upon the water when disturbed. 

 (Often found upon rafts of floating vegetation.) 



B. Very small plump-bodied bugs, usually black and silver, 

 or mottled with brown. 



C. Antennse 4-segmented. 



D. Tarsal claws anteapical. Veliidae. 



(genus Microvelia.) 



DD. Tarsal claws apical. Hehridx. 



(genus Merragata.) 



CC. Antennae 5-segmented. Hebridse. 



(genus Hebrus.) 



BB. Fairly slender green or yellowish-green bugs. 



Mesoveliidae. 

 BBB. Very slender, elongate bugs. Hydrometridse. 



AAA. Coursing upon the water by quick, jerky movements. 

 B. Fresh water. 



C. On quiet or moderately flowing waters. 

 D. Medium to large insects. 



E. With distinct abdomen. 



Gerridse. 

 (genus Gerris.) 

 EE. Without distinct abdomen. 



F. Color uniformly dark. 



Gerridse. 

 (genus Metrobates.) 



FF. Color dark, pictured with yellow. 



Gerridse. 

 (genus Trepobates.) 



