248 HETEROPTERA. 



mate in early spring. The white cylindrical eggs hatch after 

 some ten days or two weeks, the rapidity of the transforma- 

 tion depending on temperature and humidity. There are in 

 this species also five nymphal instars, and the life cycle is in 

 the neighborhood of five or six weeks. It ranges practically 

 over the entire continent, from Canada into Mexico, where I 

 have taken it. 



Gerris {G.) buenoi Kirkaldy ; 1911, Ent. News, vol. xxii, p. 246. 



This species has been frequently confounded in collections 

 with the preceding one. It is, however, much smaller, and 

 very easily separated from 7narginatus by the genital struc- 

 ture and flavescent pronotal margin. It also frequents still 

 waters, but is far more uncommon than the preceding. So 

 far nothing seems to be known of its life-history, but doubt- 

 less it could be easily worked in aquaria. Its range, to my 

 certain knowledge, is from British Columbia down to New 

 Jersey. 



Gerris (C.) canaliculatus Say; 1832, op. c, 807; 1859, op. c, 

 363. 



This form, rather rare in the North becomes more abundant 

 as we go South. It frequents still ponds, and even when at 

 large its slim body and long antennas distinguish it from its 

 relatives marginatus and buenoi. The long antennae also bring 

 it near to the Central American species of the subgenus. Its 

 chosen haunts are secluded little coves and bays in ponds, 

 where it paddles quietly about seeking its prey. Owing to 

 its scarcity it is not possible to say much definitely as to its 

 hibernation or breeding habits. The ova, however, are simi- 

 lar to those of the other species of the genus, and the period 

 of hatching and development vary but little from the others 

 observed. The nymphal stages are five. In this species I 

 was able to raise about thirty individuals from ova deposited 

 in my aquaria, all the progeny of one apterous female, and 

 every one was macropterous. This female was taken swollen 

 with ova, which she deposited in my aquarium to the number 

 of about thirty, which left her quite slim once more. She 

 deposited three or four more similar batches, and although 

 there was no male with her, all were fertile. This species 



