FOREWORD. 
It has been the aim of the writer to gather together, within 
the covers of one volume, the gist of all the information now 
available concerning the biology of the aquatic Hemiptera. 
There was no intention in the beginning to include descrip- 
tions of species or other taxonomic matter. It was found, 
however, that there exists no work containing the descriptions 
of American genera and species.* These have been gathered 
together from various sources, some of them well nigh inac- 
cessible, and are included in this paper to facilitate further 
study in the group. 
The writer does not pretend to be an authority on systematic 
literature. He has followed Van Duzee’s checklist and cata- 
logue faithfully, digressing only in those cases where he has 
had the advice from taxonomists in the various families. Keys 
have been improvised from the literature, reduced to a synop- 
tic plan, and tested upon all available material. This phase 
of the work, however, has been secondary and incidental to 
the main problem of extending the range of our knowledge of 
the ecology and biology of the water bugs. To this end the 
writer has searched the early literature for the first biological 
notes applied to the water bugs, has gleaned the periodicals, 
other serials and texts, and arranged the results in this paper 
under the families and genera as they now stand, adding his 
own contributions on the behavior, life history and ecological 
relations of these most interesting insects. 
* Generic descriptions are often brief notes and specific descriptions are omitted for 
Belostomatids# and Corixide, groups now undergoing careful revision. 
(7) 
