Preface 



Aquatic entomology is a large and diverse science. It 

 partakes of many fields and, in its applied aspects, is 

 pursued by persons with quite unrelated interests and 

 objectives. Specialists in mosquito control, for exam- 

 ple, are not directly concerned with problems of stream 

 and lake management for the production of fish, and 

 limnologists generally are inclined to stress physical 

 and chemical studies and plankton investigations 

 rather than trying to deal with numerous and imper- 

 fectly known insects. 



It is the purpose of this study to point out the cen- 

 tral role of insects in aquatic situations, to bring to 

 bear on insects the basic concepts and tools of lim- 

 nology, and to provide keys and illustrations to aid in 

 the identification of aquatic insects. It is probably 

 this last aspect of the subject that has been the 

 greatest stumbling block to progress in the past. 

 Insects comprise about four-fifths of the Animal 

 Kingdom, and only time and intensive research can 

 overcome the obstacle of such numbers of species. 

 Because of limitations of time, space, and size it 

 has been necessary to restrict the treatment at the 

 species level to California and adjacent regions. 

 However, the California fauna is fairly representative 

 of much of the western United States because of the 

 diverse elements that are included within the geo- 

 graphical boundaries of the state. At the generic 

 level a more comprehensive treatment was feasible, 

 so keys are given to all the genera known from North 

 America. 



Most books are the result of the work of many 

 people, and this is particularly true of the present 

 volume. It is a direct outgrowth of University of 

 California Syllabus SS Biology of Aquatic and Littoral 

 Insects (Entomology 133, by R. L. Usinger, Ira La 

 Rivers, H. P. Chandler, and W. W. Wirth, University 

 of California Press, 1948), now out of print, which 

 was tested in the laboratory and in the field and was 

 used for several years in classes at various insti- 

 tutions in the West. The syllabus was frankly a 

 compilation of existing knowledge with comparatively 

 little original work. It was meant to be a one-volume 

 working "library." Now, after eight years, it can be 

 said that the objectives of the syllabus have been 

 realized. Extensive collections have been gathered 

 from all parts of the state, and specialists have 

 devoted much time and effort to each group. The 



results are offered at this time as original contribu* 

 tions, each chapter written b) an authority who i- 

 most intimately acquainted with our fauna. II In 

 tions have been added to clarifs the text, and a 

 glossary explains the technical terms that are not 

 understandable from the figures. Much remain- to I" 1 

 done in every group, but it can now bo said that we 

 have a sound foundation on which to build. 



Acknowledgments 



The editor is personally grateful to the « r °up of 

 distinguished collaborators, each of whom has given 

 generously of his research time to make this volume 

 possible. We are indebted also to all those students 

 who have contributed to the store of knowledge on 

 aquatic insects, a rich heritage from which we have 

 drawn heavily. Detailed acknowledgments are given 

 in each chapter and on nearly every page, but a few 

 persons or institutions have contributed so exten- 

 sively that they are deserving of special mention here. 



For advice and assistance in the introductory 

 sections, thanks are due to Paul R. Needham (general 

 principles, stream and lake management); F. R. 

 Pitelka (ecology); R. F. Peters, J. R. Walker, A. C. 

 Smith, and T. D. Mulhern in the Bureau of Vector 

 Control, State Department of Public Health (mosquito 

 control); E. A. Smith and E. H. Pearl of the Santa 

 Clara County Health Department (mosquito control); 

 W. R. Kellen, Research Entomologist, U.S.P.H.S. 

 grant for study of insects in relation to sewage dis- 

 posal; and Dana Abell, National Science Foundation 

 Fellow (stream classification). Man) of the sug- 

 gestions of the above-mentioned specialists have been 

 incorporated, but it should be made clear that the 

 author alone is responsible for the final version. 

 Valuable assistance was furnished in the final prep- 

 aration of the manuscript by the following: J. D. Lattin 

 (photographic copy of illustrations), W. C. Bentinck 

 (glossary), and Jon Herring (index). 



For fundamental works in taxonomy, we are indebted 

 to Dr. J. G. Needham and his colleagues and students 

 at Cornell University, and to the late S. A. Forbes 

 and T. II. Frison and to H. II. Ross and others at 

 the Illinois Natural Historv Survey who have done 



