particularly, 13. 



fauna is poorer. In the latter cases, 

 more collecting may alter the figures. 



ECOLOGY 



The aquatic and semiaquatic Hemiptera occupy a wide 

 variety of habitats from salt-water pools to mountain 

 lakes and from hot springs to large rivers. In general, 

 they fill the role of predators at intermediate stages 

 in the food chains of their respective communities. 

 Some, such as the surface stridors, appear to be 

 complete masters of their environment, whereas others, 

 such as the relatively defenseless Corixidae, are 

 generally preyed upon. Corixids are partly responsible 

 for the primary conversion of plant material into 

 animal food, but it now seems clear that they cannot 

 subsist on the "flocculent ooze" alone but must take 

 animal food, such as small mosquito larvae, as a 

 part of their diet. 



Although each genus of aquatic Hemiptera occupies 

 a characteristic habitat and exhibits distinctive 

 behavior patterns, it is difficult to organize such 

 information in a useful way. Hungerford (1920) gave 

 a "Habitat Key" which has been modified below, 

 adapted to the California fauna, and enlarged with 

 new information gleaned from the literature and expe- 

 rience of the last thirty-five years. 



Key to California Aquatic and Semiaquatic Hemiptera 

 Based on Habits and Habitats 



1. True aquatics, living beneath the water 2 



— Surface or shore bugs 10 



2. Respiration by breaking surface film with pronotum 

 3 



— Respiration via tip of abdomen or abdominal appendages 



4 



3. Salt or brackish waters CORIXIDAE— Trie hocoHxa 



— Fresh waters other CORIXIDAE 



4. Respiration by breaking surface film with tip of abdomen 



5 



— Respiration by long, slender "tube" or short, retractile 

 flaps 8 



5. Back swimmers 6 



— Swimming with dorsum uppermost 7 



6. Limnetic, resting poised in open water 



NOTONECTIDAE— Buenoa 



— Resting on submerged objects or at surface film .... 



NOTONECTIDAE— Notonecta 



7. Living amidst rocks in streams and lake margins . . . 



NAUCORIDAE— A mbrysus 



— Living amidst aquatic vegetation in ponds 



NAUCORIDAE— Pelocoris 



8. Awkward swimmers, living in trash and tangled plants 



NEPIDAE 



— Strong swimmers, hiding in protected places 9 



9. Eggs laid on stems of rushes and the like 



BELOSTOMATIDAE — Lethocerus 



— Eggs laid on backs of males 



BELOSTOMATIDAE— Abedus, Belostoma 



10. Surface bugs 11 



— Shore bugs 17 



11. Living on open water surface 12 



— Living at water's edge or on floating vegetation, running 

 on open water when disturbed 15 



12. Marine GERRDDAE— Halobates 



— Fresh waters 13 



14. 



15. 

 16. 



17. 

 18. 



19. 



20. 

 21. 

 22. 



23, 

 24 



185 

 Usinger: Hemiptera 



Living on ponds, lakes, and quiot waters of Btri 



GERR1D AE—Oerria, Trepobates 



Living on swiftly flowing streams, gregarious 11 



Living on riffles, usually of small streams and river a 



V V.\ Ml) \\:—K hagovelia 



Living on open water, usually of largo rivers 



GERRIDAK— Metrobates 



Delicate "treaders" on long, stiltlike legs in protected 



places HYDROMETRIDAE 



Rapid "skaters" on shorter legs in open places .... 16 

 Resting on surface film near shore, gregarious 



VELIIDAE— Microvelia 



Resting on floating leaves, and the like, more solitary 



MKSOVELIIDAE — Mesovelia mulsanti 



Walking or running forms 18 



Jumping or flying forms 22 



Swift runners, beneath stones at water's edge 



DIPSOCORIDAE 



Slow walkers at water's edge, stones, moss, etc. ... 19 

 Capable of skating on surface film when disturbed 



MESOVELIIDAE — Mesovelia amoena 



Not capable of skating on surface film 20 



On dry land near water MACROVELIIDAE 



At water's edge 21 



Under stones or on moss IIEBRIDAE — //ebrus 



On floating mats of algae IIEBRIDAE — Merragata 



Jumping forms, concealed by coloration of sand or mud 



23 



Jumping and/or flying forms 24 



Exposed on sand or mud; eggs in sand 



GELASTOCORIDAE— Gelastocoris 



Hiding in mud under rocks; eggs brooded in mud cell 



GELASTOCORIDAE— Nerthra 



Moving by short, quick jump-flights SALDIDAE 



Moving by longer flights or hiding near water 



OCHTERIDAE 



BIOLOGY. 



In general, water bugs overwinter as adults, lay eggs 

 in the spring, develop during the summer, and then 

 repeat their yearly cycle. Only a few exceptions to 

 this are noted in the following pages. There are five 

 nymphal instars in all but a few species of Microvelia. 

 Eggs are laid in a wide variety of places, each usually 

 characteristic for a particular species. Unlike many 

 aquatic insects no water bug is known to deposit its 

 eggs freely to float on the surface or in the water. 

 The eggs are glued to various objects including the 

 backs of males (Belostoma and Abedus). Bug eggs 

 can usually be recognized by the relatively tough, 

 hexagonally reticulate chorion and by buttonlike or 

 peglike micropylar processes. They are usually oval, 

 occasionally spindle-shaped, and sometimes stalked. 

 A key to eggs and egg-laying habits is given below 

 with some diffidence because information on this 

 subject is so inadequate. 



Key to the Eggs and Egg-Laying Habits of California 

 Aquatic and Semiaquatic Hemiptera 



1. Eggs stalked and attached by the end opposite the 

 micropyle 2 



— Eggs not stalked, inserted in plant tissue or glued to 

 the substrate 3 



2. About 6 times as long as greatest diameter; brown in 

 color with longitudinal fluting at middle, the tapered 

 end reticulate HYDROMETRIDAE 



