186 



Usinger: Hemiptera 



— Suboval in shape, white, with the micropylar end briefly 

 produced as a small nubbin (fig. 7:4) CORIXIDAE 



3. Two threadlike filaments at micropylar end, longer than 

 the egg itself; egg inserted in plant tissue with only 

 the filaments projecting NEPIDAE — Ranatra 



— No threadlike filaments 4 



4. Micropylar end with a small, cylindrical, bent projection 



5 



— Micropylar end without such a bent projection 6 



5. A smooth elongate oval area on anterior half of upper 

 surface. Eggs inserted in plant tissue, the smooth area 

 exposed NOTONECTIDAE— tfuenoa 



— Without such a smooth area, eggs inserted or glued to 

 the substrate NOTONECTIDAE— Notonecta 



6. Micropylar end narrowed and bent as a curved neck 

 terminating in a flat surface which is exposed, the rest 

 of the egg being inserted in plant tissue 



MESOVELIIDAE 



— Form oval or subcylindrical, not narrowed as above, 

 and not inserted in plant tissue 7 



7. Attached vertically by the end opposite micropyle; 

 color brown; laid in clusters of 100 or more, the individ- 

 ual eggs contiguous 8 



— Attached horizontally, glued to leaves of aquatic or 

 shore plants, floating or submerged objects, or laid 

 free 9 



8. Laid in a clump on the folded hemelytra of the male 



BELOSTOMATIDAE— Abedus, Belostoma 



— Laid in a mass above the water on cattail stalks or 

 other objects BELOSTOMATIDAE— Lethocerus 



9. Oval, about twice or less as long as wide 10 



— Elongate-oval, about 3 or more times as long as wide 

 13 



10. Twice as long as wide; glued to objects under water 

 NAUCORIDAE 



— Less than twice as long as wide, laid in sand or mud 

 or at the bases of clumps of grass, out of water .... 11 



11. Laid in clumps of grass and roots OCHTERIDAE 



— Laid in sand or mud 12 



12. Laid amidst sand grains 



GELASTOCORID AE—Gelastocoris 



— Laid in small holes in mud several feet from shore, 

 beneath stones, the female "guarding" the eggs 

 GELASTOCORID AE—Nerthra 



13. Laid just beneath the surface film on floating or 

 emergent objects 14 



— Laid out of water at the bases of clumps of grass or 

 moss 15 



14. Length usually more than 1 mm.; often laid in rows, the 

 individual eggs not contiguous, laid side by side 

 GERRIDAE 



— Length less than 1 mm.; laid individually or in irregular 

 clusters .VELIIDAE 



15. Shape elongate-oval HEBRIDAE 



— Slightly tapering and bent toward micropylar end 



SALDIDAE 



Flight. — Only the marine Halobates, among Cali- 

 fornia Hemiptera, have lost their wings completely. 

 Others are capable of flying at times, and there is 

 no doubt that this ability has real survival value in 

 an area where rainfall is low and seasonal, and many 

 ponds and streams dry up for a part of each year. 

 Macan (1939) recorded the recolonizing of a fountain 

 at King's College, Cambridge, England, throughout a 

 period of six years, and found twenty-six species of 

 aquatic insects including seven corixids and one 

 notonectid. No study of this kind has been made in 

 California, but corixids (Corisella) and belostomatids 

 (Lethocerus) are frequently attracted to lights, some- 

 times in large numbers, during the summer months in 

 the Sacramento and San Joaquin valleys. 



Wing polymorphism is typical of members of the 

 superfamily Gerroidea and is dealt with in the dis- 

 cussion of each of the families in which it occurs. 

 Despite the studies by Poisson (1924) and others on 

 wing polymorphism, a full understanding of the genetic 

 factors and environmental influences is lacking. 

 Curiously, some of the macropterous Gerridae (Halo- 

 batinae) break off the wings, presumably during mating. 



Stridulation. — A great deal has been written about 

 sound production in water bugs, but firsthand records 

 of noises that have been heard are rare indeed. Hun- 

 gerford (1924) heard a Buenoa stridulate, and it 

 appears certain that the structures seen in certain 

 corixids are for this purpose. Details are given under 

 each family. 



Respiration.-*- -Each of the truly aquatic families 

 has a distinctive type of respiration which will be 

 discussed later in detail. In general, water bugs are 

 dependent on surface air obtained through tubes 

 (Nepidae), flaps (Belostomatidae), the tip of the 

 abdomen (Naucoridae, Notonectidae), or the pronotum 

 (Corixidae). Only certain exotic naucorids (Aphelo- 

 cheirus) can live exclusively on dissolved oxygen, 

 obtained through a submicroscopic plastron. Corixids, 

 notonectids, naucorids, and belostomatids gain a 

 large part of their oxygen by diffusion into the air 

 "bubble" or film held by hydrofuge hairs on their 

 ventral surfaces. This type of respiration was first 

 described by Comstock (1887) and later elaborated 

 by Thorpe (1950). 



Collecting methods and rearing techniques. — : Water 

 bugs are obtainable without special equipment. A 

 nylon net will serve for all forms in or on the water, 

 and a screen or dredge may be used in dense aquatic 

 vegetation. For shore bugs and species that live at 

 the water's edge painstaking search must be made 

 beneath rocks and in moss and other marginal plants. 

 Bogs may be collected by pressing the vegetation 

 down and floating specimens out. Swift-moving water 

 striders are best collected by a quick downward stroke 

 of the net, followed by a twist as it splashes on the 

 water. Stream forms such as Ambrysus may be taken 

 by holding the net downstream and dislodging the 

 bugs by moving rocks above the net. Saldids and 

 other jumping forms can be made to jump into the net 

 by holding it still with one hand while approaching 

 the specimen from the opposite side with the free 

 hand. Light traps are useful for a very few species 

 that fly regularly, but a light at the water's edge has 

 been found to attract various species including 

 Ambrysus. Berlese funnels are useful for small shore 

 dwellers such as hebrids, dipsocorids, and saldids 

 that regularly inhabit trash and vegetation at the 

 water's edge. 



Any water bug may be preserved in alcohol, but 

 most study collections consist of pinned or pointed 

 specimens. In most cases it is useful to have some 

 specimens dried and others in alcohol. The latter are 

 ideal for dissection and for careful study under the 

 higher powers of the dissecting microscope. Of course 

 dried specimens may be softened in KOH and dis- 

 sected or studied intact, but this usually results in 

 damaged or destroyed specimens. 



