Giant Water Bugs

Belostomatidae, Lethocerinae, Lethocerus. Spanish: Cucarachas del agua (General). Portuguese: Baratas d'agua (Brazil). Electric light bugs, toe biters.

Belonging to a cosmopolitan f amily, this genus has speciated prolifically in Latin America. There are nearly twenty distinct species, mostly in the genus Lethocerus (Menke 1963). The two species L. maximus (fig. 8.5a) and L. grandis are among the largest of insects with a body length up to 11.5 centimeters and weight of 15 to 25 grams.

All are much flattened, ellipsoid in outline, and shiny dark brown. The head is rigidly fixed to the thorax and does not rotate; its frontal portion projects strongly forward between the eyes. Straplike, retractile respiratory appendages are borne at the tip of the abdomen. The latter penetrate the surface film when the bug ascends, rearward, to take in air. Most of the store is carried under the wings in a cavity created by the depressed abdomen.

These are rapacious predators, catching all sorts of other aquatic invertebrates and even small vertebrates like tadpoles and fish with their raptorial forelegs, then killing them with a vicious stab of the mouth stylets. The rostrum acts like a hypodermic syringe, injecting saliva that both immobilizes and digests the organisms on which they feed (Picado 1937). The bugs wait patiently in ambush among plants or debris in the water, relying on remaining motionless and on their cryptic coloration to escape detection by their

Figure 8.5 WATER BUGS, (a) Giant water bug (Lethocerus maximus, Belostomatidae). (b) Back swimmer (Buenoa pallens, Notonectidae). (c) Salt marsh water boatman (Trichocorixa reticulata, Corixidae). (d) Common water strider (Gerris remigis, Gerridae). (e) Sea strider (Halobates micans, Gerridae).

prey. Female giant water bugs lay their eggs on emergent aquatic vegetation, not on the back of males as is characteristic of other genera in the family.

Specimens may be common at times near their well-vegetated, marshy pond and lakeshore habitats. On warm evenings during their dispersal season, they sometimes accumulate under electric lights and attract a great deal of attention (Lanzer 1975). The biology of L. maximus has been investigated in some detail in Trinidad (Cullen 1969) and it has been maintained in the laboratory for studies on the physiology of its flight muscles (Barros 1973).

References

Barros S., M. C. 1973. Manten^ao da barata d'agua gigante (gen. Lethocerus) no labora-torio. Univ. Sao Paulo, Inst. Biol. Mar., Bol. Zool. Biol. Mar. (Nov. Ser.) 30: 613-623. Cullen, M. J. 1969. The biology of giant water bugs (Hemiptera: Belostomatidae) in Trinidad. Royal Entomol. Soc. London Proc. A 44: 123-136.

Lanzer, M. E. B. 1975. Nota previa sobre o comportamento de Belostorna Latreille, 1807 e Lethocerus Mayr, 1853 em aquario e no meio ambiente. Iheringia (Ser. Div.) 4: 47-50. Menke, A. S. 1963. A review of the genus Lethocerus in North and Central America, including the West Indies (Hemiptera: Belostomatidae). Entomol. Soc. Amer. Ann. 56: 261-267.

Picado T., C., 1937. Estudo experimental sobre o veneno de Lethocerus del-pontei (DeCarlo) (Hemiptera-Belostomidae). Inst. Butantan (Sao Paulo) Mem. 10: 303-310, figs. 1-3.

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