CHAPTER 7 



Aquatic Hemiptera 



By R. L-. Usinger 



University of California, Berkeley 



Sixteen families of Hemiptera occur in, on, or near 

 the water. These include the water boatmen (Cori- 

 xidae), back swimmers (Notonectidae), water scorpions 

 (Nepidae), giant electric light bugs (Belostomatidae), 

 toad bugs (Gelastocoridae), shore bugs (Saldidae), 

 the several families of surface striders, and a few 

 others. All agree in having sucking mouth parts usu- 

 ally in the form of a slender, three- or four-segmented 

 beak; antennae of not more than five segments, usually 

 of four segments but variously reduced and concealed 

 in the true aquatics; tarsi of not more than three 

 segments; and the fore tarsi sometimes greatly reduced 

 or absent. The wings, when present, have relatively 

 few veins. Scent gland openings are present at the 

 sides of the thorax in some forms, including Corixidae. 

 A single opening occurs at the middle of the metaster- 

 num in Gerridae and Hydrometridae, and dorsal abdom- 

 inal scent glands occur in the nymphs of Corixidae 

 and Dipsocoridae (3), Saldidae, Mesoveliidae, and 

 Macroveliidae (1), and Naucoridae (1 pair). 



The aquatic Hemiptera are not homogeneous. Each 

 family is distinctive in structure and habits, and the 

 group as a whole is certainly polyphyletic. China 

 (1955a, 19556) summarized knowledge of hemipterous 

 phylogeny and gave his views on the probable evolu- 

 tionary lines of surface bugs and under water bugs in 

 the form of diagrams (figs. 7:1; 7:2). 



Acknowledgments 



Dr. H. B. Hungerford of the University of Kansas 

 gave a brief history of studies on aquatic Hemiptera 

 in the introduction to his classical work, The Biology 

 and Ecology of Aquatic and Semiaquatic Hemiptera 

 (1920). This pioneer contribution is quoted on nearly 

 every page of the present work. In addition, Dr. 

 Hungerford has been an inspiration and help to me 

 and to generations of students in the years since 

 1920. He is personally responsible for most of the 

 great advances in this field, and he was good enough 

 to read much of the present work in manuscript form. 

 Dr. R. I. Sailer also read nearly all the manuscript 



182 



and made several valuable suggestions. J. L. Herring 

 made substantial contributions to the manuscript 

 during the later stages of its preparation. 



Others who have contributed indirectly or directly 

 to this work are P. R. Uhler (1884), G. W. Kirkaldy, 

 whose Guide to the Study of British Waterbugs (1898- 

 1908) served as an introduction to the subject; the late 

 J. R. de la Torre-Bueno, whose collection is now at 

 the University of Kansas; the late E. P. Van Duzee, 

 whose Catalogue (1917) is still the main source of in- 

 formation on literature and whose collection at the 

 California Academy of Sciences was a valuable source 

 of records; C. J. Drake and H. M. Harris, whose work at 

 Ames, Iowa, has provided indispensable monographs 

 of several groups, and a host of graduate students 

 at the University of Kansas including: Kuitert, Cum- 

 mings, Sailer, Hidalgo, McKinstry, Hodgden, Martin, 

 Porter, Gould, Wiley, Evans, Truxal, Bare, Hoffmann, 

 and Todd. Important contributions by others include 

 O. Lundblad and T. Jaczewski (Corixidae), G. E. 

 Hutchinson (Corixidae and Notonectidae), Jose 1 de 

 Carlo (Belostomatidae, Nepidae, and Naucoridae) 

 and Ira La Rivers (Naucoridae). Valuable help in 

 collecting has been given by the late Harry P. Chand- 

 ler and J. D. Lattin. Some general works on aquatic 

 Hemiptera of other parts of the world are: Blatchley 

 (1926), Butler (1923), Abbott and Torre-Bueno (1923), 

 Uhler (1884), Macan (1941), Herring (1950-1951), 

 Zimmerman (1948). 



The most recent account of the aquatic Hemiptera 

 of California is by Usinger (in Usinger, La Rivers, 

 Chandler, and Wirth, 1948). For the present study the 

 1948 keys have been completely revised, synonymy 

 has been rechecked and revised, and many new records 

 have been added. 



For the illustrations of whole insects I am indebted 

 to Arthur Smith, British Museum (Natural History) and 

 for funds, to the Research Committee, University of 

 California. Mrs. Frieda Abernathy is responsible for 

 figures 7:7, 7:26, 7:36, and 7:37, prepared originally 

 for Zimmerman's Insects of Hawaii, and figure 7:12. 

 The anatomical drawings of Corixidae (figs. 7:3; 7:9) 

 and Microvelia (fig. 7:31) were made by Mrs. Celeste 

 Green. 



