J. R. DE LA TORRE BUENO. 247 



about three weeks, according to the temperature, and after 

 five molts reach the adult or perfect stage in some four 

 weeks more. In the favorable conditions of heat, food and 

 moisture ruling in an aquarium, the period of development is 

 probably at a minimum. Their food consists of such insects 

 as have the misfortune to fall into the water, on which they 

 pounce and after rendering them unconscious by means of 

 their narcotic saliva, they feast at their leisure. Both young 

 and adults are parasitized by a bright red mite. 



This species ranges from Labrador and British Columbia 

 south into Mexico and east of the Rocky Mountains. Thus 

 far it has been reported from the following States : Maine, 

 New Hampshire, Massachusetts, Connecticut, New York, 

 New Jersey, Pennsylvania, Maryland, Illinois, Michigan, 

 Texas, Colorado, Arizona, Oregon, California, North Caro- 

 lina, Georgia, Louisiana, etc. It seems to be very wide- 

 spread, but we have no actual records other than those cited. 



Gerris {Aguarius) coiiforinis Uhler ; 1878, Proc. Boston Soc. Nat. 

 Hist., xix, p. 435. 



The long produced abdominal processes of this form sepa- 

 rate it sharply from its congener G. remigis, and the generic 

 characters given in the tabe differentiate it from G. rufoscu- 

 tellatus with which it might be mistaken. Further differ- 

 ences between it and remigis are the comparatively longer 

 form, decidedly longer legs, more prominent eyes, etc. So 

 far as my experience goes, it is distinctly an inhabitant of 

 flowing waters, where its very long legs attract attention 

 and make it recognizable even at a distance. In this latitude 

 I have never seen it in the short-winged or wingless form, 

 although I have specimens (brachypterous) from Louisiana. 

 Apparently nothing is known of its life history, but it is car- 

 nivorous like the other Gerrids. Its range extends at least 

 to Louisiana. 



Gerris {Gei-ris) niarg-iiiatus Say; 1832, op. c, p. — (Fitch re- 

 print, p. 807); 1859, Compl. Writings, i, p. 362. 



This small stout form is an abundant inhabitant of our 

 lakes and ponds, where it preys on other insects. Like its 

 larger cousin remigis, it hibernates as an adult, and begins to 



TRANS. AM. ENT. SOC. XXXVII. 



