APHELOCHEIRINAE 

 Plastron 



Respiration 



183 

 Usinger: Hemiptera 



NAUCORIDAE 



■ 



1 Pair Larval 



Abdominal Scent Glands 



RANATRA 

 Elongation of 



BELOSTOMATIDAE 



■ 



Life in Open Water, 



Siphon Reduced, 



Body, Lengthening Swimming Legs 

 Developed 



of 



Life 



Siphons 



Amongst Weeds 

 Deeper Water 

 NEPIDAE 



Loss of 

 Metothoracic 

 Scent Glonds 



% 



Life in Shallow 

 Water Neor Shore 



NOTONECTIDAE 



Perfection of Body Form 

 ond Legs for Swimming 



PLEIDAE Abdominal Larval 

 Reduction of Scent Glands Absent. 

 Antennae to 3^ 



HELOTRE_PHIDAE 

 Fusion of Head 

 with Pronotum 

 Reduction of Ovipositor 

 Antennae I^Developed 

 to 2 or 1 J 



Single Opening of 

 Larval Abdominal 

 Scent Gland 

 PROTO-HELOTREPHIDAE 



Larval^bdomtnal 



Scent Glands Absent 



PROTO-BELOSTOMATIDAE 



Siphon Disappe 



Respiration of 0ce 

 Disappearance 



of OceM_i Air-Bubble 



Respiration 



CORIXIDAE 

 ■ 

 3 Pairs Larval 

 Abdominal Scent Glands 



I 



Disappearance 

 of Ocelli 



DIAPREPOCORIS 



GELASTOCORIDAE 

 Terrestrial, Littoral 



OCHTERIDAE 

 Terrestrial, Littoral 



PROTO-NAUCORIDAE 



Aquatic 



Pharyngeal Teeth 



PROTO-GELASTOCORIDAE 



PROTO-OCHTERIDAE 

 Terrestrial 



I 



PROTO-HETEROPTERA 

 Fig. 7:1. Probable evolutionary lines of woter bugs (China, 1955). 



DISTRIBUTION 



California has a diverse hemipterous fauna. On the 

 north coast and in the mountains (Transition Zone 

 and above) are found boreal elements common to the 

 northern United States and Canada. On the east slope 

 of the Sierra, including parts of Lassen County and 

 the Owens Valley, Great Basin species are found. 

 Then, along the Colorado River bordering Arizona 

 occur species typical of the Sonoran region. Of 

 particular interest are the relict forms found in iso- 

 lated springs in the midst of the southern deserts. 

 These springs are relict habitats, mere vestiges of 

 more extensive lakes and streams of former times. 

 That the aquatic Hemiptera were not very different 

 during the recent past, however, is indicated by 

 species in the La Brea and McKittrick tar pits (Pierce, 

 1948) (Belostomatidae, Notonectidae, and Nepidae) 

 which differ only slightly, if at all, from present-day 

 forms in the same area. The age of these fossils is 

 presumably about 10,000 years. 



TABLE 7: 1 



Comparison of Number and Percentages of Aquatic 

 Hemiptera of California and the British Isles 



Hemiptera 



Cali 



ornia 



Brltis 



1 Isles 



Speoles 



Per cent 



Spec ies 



Per cent 



Corixidae 



29 



25.6 



35 



41.2 



Notonectidae 



11 



9.7 



4 



4.8 



Pleidae 











1 



1.2 



Naucoridae 



8 



7 



2 



2.3 



Belostomatidae 



5 



4.5 











Nepidae 



3 



2.6 



2 



2.3 



Gelastocoridae 



4 



3.5 











Ochteridae 



1 



1 











Gerridae 



11 



9.7 



10 



11.7 



Veliidae 



8 



7 



4 



4.8 



Hydrometridae 



1 



1 



2 



2.3 



Macroveliidae 



1 



1 











Hebridae 



4 



3.5 



2 



2.3 



Mesoveliidae 



2 ' 



1.7 



1 



1.2 



Saldidae 



24 



21 2 



20 



23.5 



Aepophilidae 











1 



1.2 



Dipsocoridae 



1 



1 



1 



1.2 



Total 



113 



100 



85 



100 



