76 THE CANADIAN ENTOMOLOGIST. 



differs, however, from the adult in having the tarsi one-, instead of three- 

 jointed. The body is so soft at birth and during the five mouhs which 

 follow that the nymphs are frequently drowned, not being able to raise 

 their bodies above the surface film so easily as do the more rigid adults. 

 During the summer there are varying numbers of broods, depending 

 largely upon the length and temperature of the season, for this simple life- 

 history is repeated as fast as the insects reach maturity. 



Hydrometra is a carnivorous insect, its food consisting of the juices 

 of insects that fall into the water, and the number of these is considerable 

 along the grassy aquatic borders. When such a hapless insect falls into 

 the water it is at once pounced upon by one or several voracious Hydro- 

 metras, who insert their beaks and proceed to suck the juices from their 

 still struggling victim. I have seen no less than ten thus surround their 

 prey, all with their heads in the direction of common interest and their 

 bodies radiating outward. The body and legs of Hydrometra are covered 

 with minute hairs, which prevent the body from being easily wet. The in- 

 sect is constantly engaged in lifting its legs into the air to dry them, forif they 

 once become wet they sink through the surface film just as would a float- 

 ing needle. When Hydrometra does break through the surface film he is 

 often able to free one leg after another, and then by main force raise his 

 body up also. 



In Lethierry and Severin's Catalogue of the Hemiptera there are 

 listed eleven species of Hydrometra, but this list is not complete, for it 

 does not contain H. lineata. These eleven species are mostly tropical 

 and sub-tropical, with the exception of the European species and one 

 from Siberia. One species from the Philippines may eventually become 

 a member of the fauna of the United States, though at present H. lineata 

 is our sole representative of this genus. It seems that subsequent study 

 will show more species within the boundaries of the United States, and 

 that Say's variety australis will be found to be a distinct species. 



