30 Journal New York Entomological Society. tVoi. xxi. 



In all of these the most striking adaptations of structure are con- 

 nected with habits of locomotion, breathing and feeding, which are 

 variously modified to suit the particular environment referred to 

 above. With few exceptions these are all carnivorous and are 

 equipped with the short stout beaks necessary for piercing the tissues 

 and sucking the juices of animals. Correlated with this, the great 

 majority have the fore legs modified for seizing and holding the prey. 



Although a few forms in the west have been recorded as occurring 

 in water strongly impregnated with various mineral salts, and a few of 

 our local forms in brackish water, they are for the most part strictly 

 fresh water forms. The species likely to occur in any body of water is 

 determined somewhat by the character of the water, the nature of the 

 current and the presence or absence of accumulated plant life. Some 

 species preferring the swift moving stream in which they seem to love 

 to sport against the force of the current; others, and perhaps the 

 greatest number, are found only in still waters of ponds or the quiet 

 waters of bayed out parts of streams where they sometimes congre- 

 gate in immense numbers. 



Quite a number of these aquatic hemiptera, notably members of 

 the families Belostomatidse, Corixidje and Notonectidse, have well- 

 developed wings and readily migrate from one body of water to an- 

 other and at such times, as has been frequently observed, are at- 

 tracted to bright lights. The great majority of species, however, 

 are fixed in their environment and though provided with wings are 

 frequently incapable of flight. Others are dimorphic as to wings. 

 In the Gerridae and allied families there occur a number of species 

 in both the winged and unwinged state. 



The species which live actively upon the surface of the water 

 belong to the following families, Gerridae, Veliadae, Hydrometridse, 

 Neogeidse and Mesoveliadge. They have more or less elongated bodies 

 and slender legs. The beautiful ease with which they glide and skip 

 about over the surface of the water is due to the fine plush-like coating 

 of hairs on the feet and ventral parts of the body by means of which 

 they are enabled to enmesh a thin film of air which sustains their 

 weight on the surface film and keeps the body dry. Unlike the mem- 

 bers of the second and third groups the antennae are well developed 

 and exposed. As they breathe surface air they have no peculiar 

 method of respiration differing from terrestrial forms. Some of these 



