Vol. XXviii] ENTOMOLOGICAL NEWS 205 



opening of the stink-gland. This omphalium is perfectly visi- 

 ble in G. remigis, in specimens with a reddish venter ; in dark 

 individuals it is difficult to see, but with care may be detected 

 readily. It also appears to vary in size somewhat and is plac- 

 ed at the caudal margin of the metasternum, right at the su- 

 ture. N. Leon^ states that the Gerridae have labial palpi, which 

 I have not detected in our species. Fyles^ finds remigis weighs 

 one grain. Henneguy^ refers to the number and structure of 

 the malpighian tubes in the genus and to the pulsatile organs 

 in the legs (p. 87), quoting Locy and Behn. Uhler records 

 that it varies in color, a circumstance scarcely worth noting, 

 as it cuts no figure specifically, which is the reason for its men- 

 tion here. Some species are recorded to fly by night, but ours 

 have not been observed doing so. Two fossil species of the 

 genus are known from Canada, perhaps the ancestors of our 

 forms. 



Gerris remigis is extremely hard to keep in confinement. No 

 sooner is it in an aquarium than it begins to dash itself madly 

 against the sides. Now and again a tamer specimen is secured 

 and such will even breed in confinement. Ordinarily, however, 

 they get water-logged from their frantic efl^orts and, sinking, 

 drown. But even these sunken individuals, after some time, 

 as Mr. C. E. Olsen has observed, if rescued before it is too 

 late and carefully dried, may return to active life. Gerris 

 remigis, like all the other semi-aquatics, is densely clothed 

 with a velvety pubescence in all instars, which it furbishes and 

 preens and currycombs constantly, by means of the tibial 

 combs, with which each tibia is furnished, a toilet necessity 

 found in them from their earliest youth. 



A very careful study of the reactions of Gerris has been 

 made by Christine Essenberg^. She studied the Calif ornian 



5 1897. Beitrage zur Kenntniss des Labiums der Hydrocoren. Zool. 

 Anz. Bd. 20, No. 527. 

 °i9io. 41st Annual Report of the Entomological Society of Ontario, 



p- Si- 



'' 1904. Les Insectes. p. 80. 



'1915. Journ. An. Behav. v., No. 5, pp. 307-402. The Habits of the 

 Water Strider Gerris remigis. 



