No. 34.] HEMIPTERA OF CONNECTICUT: GERRIDAE. 659 



Key to Tribes. 



Posterior femora extending beyond the abdominal apex. Inner 

 margins of the eyes convexly rounded; body comparatively 

 short and broad ; abdomen so short as to appear almost nymphal 

 in some forms Tribe Halobatini 



Inner margins of eyes arcuately sinuate behind the middle; body 

 comparatively long and narrow, abdomen long Tribe Gerrini 



Tribe GERRINI. 



In the tribe Gerrini only Gerris has been recorded east of the 

 Mississippi River and north of Georgia. 



Gerris Fabricius. 



The characters of the tribe in the key will separate Gerris from 

 the other genera. This genus, however, breaks up into a number 

 of series of subgeneric rank, considered by some to be full genera, 

 but not so treated herein. They are readily separable by the 

 following key : 



Key to Subgenera. 



1. Pronotum sericeous, dull ; antennae comparatively short and stout 2 

 Pronotum glabrous, shining ; antennae long and slender 



Subgenus Limnogonus Stal 



2. First joint of antennae shorter than second and third taken together 3 

 First joint of antennae longer than second and third taken together 



(Hygrotrechus Stal) Subgenus Aquarius Schell. 



3. Antennae in length equalling half the length of the body ; sixth 



abdominal segment in the male roundedly emarginate 



Subgenus Limnoporus 

 Antennae less than half the length of the body, not extending 

 beyond the thorax ; sixth abdominal segment in the male doubly 

 emarginate (Limnotrechus Stal) Subgenus Gerris s. str. 



Key to Species. 

 Subgenus Aquarius. 



Comparatively stout species, usually found apterous ; legs short ; 

 underside of body dark ; spines of sixth abdominal segment not # 

 reaching end of genital segment .remigis 



Comparatively slender species, winged; legs long; under side of 

 body yellowish; spines of sixth abdominal segment reaching to 

 end of genital segment conf ormis 



G. remigis Say. (PI. xvi, 12.) 



Het. New Harm., 35, 1832 : Compl. Writings i, 362, 1859. 



This common form extends from Labrador to Mexico. It 

 frequents running waters in schools, in the shady slack parts. It 

 hibernates under boards or logs near its haunts, and on waking in 

 spring, lays its eggs on the water plants and grasses growing 

 along the banks. There are five molts after hatching, and the 

 whole life-cycle takes seven weeks from egg to adult. Both adults 

 and young are parasitized by a red mite which fastens to the head ; 



