Australian Biological Resources Study

Australian Faunal Directory


Regional Maps


Compiler and date details

October 2010 - Dr G. Cassis, University of New South Wales, Sydney, New South Wales


The nepomorphan family Belostomatidae comprises nine genera and 160 species (Menke 1979, Slater 1982, Štys & Jansson 1988, Polhemus, J.T. pers. comm., Henry 2009). The family is found in all major zoogeographic regions and is most diverse in the tropics. These insects are colloquially referred to as giant waterbugs, tadpole killers, electric light bugs and toe biters. Cantonese and Laotian people are known to eat Lethocerus indicus (Lepeletier & Serville) after boiling them in salted water (Miller 1956; Gope & Prasad 1983).

Belostomatids are generally very large, ranging in length from 25 to 110 mm. They are mostly elliptical, in shape and moderately dorso-ventrally flattened. The head has a triangular anteoculus, lacks ocelli, and has large eyes. The antennae are usually 4-segmented and housed in grooves below the eyes; AII and AIII have various lateral projections, which are diagnostic at the subfamilial level. The pronotum is divided into two lobes. The hemelytral membrane has reticulate veins. The Horvathiniinae and Lethocerinae have metathoracic scent glands, which are absent in the Belostomatinae. Belostomatid larvae lack dorsal abdominal glands (Staddon 1971; Aldrich 1988). The metepimeron extends posteriorly over the first two or three abdominal sterna and is fringed with long hairs. The forelegs are raptorial, strongly incrassate, with the femora often grooved to accept the tibiae. The foretarsi are either 2 or 3-segmented. The middle and hind legs are modified for swimming, being flattened and fringed with hairs. In the male, the phallus is articulated with the genital capsule and the aedeagus is divided into a phallosoma and endosoma. The eighth abdominal segment has two long, flattened, retractile respiratory straps, each with a basal spiracle (Lauck & Menke 1961; Menke 1979; Slater 1982; Aldrich 1988).

Belostomatids are voracious predators and have a varied diet that includes other insects, snails, tadpoles, small frogs and fish. Species of Lethocerus Mayr can be important pests in fish hatcheries (Wilson 1958). Species of the African genus Limnogeton Mayr are obligate feeders on freshwater snails (Voelker 1968). Belostomatids are known to inject their prey with toxins causing prey paralysis and tissue necrosis. The salivary secretions are known to contain proteases and amylases (Rees & Offord 1969). There are also incidental records of belostomatid "bites" on humans, producing painful and local reactions (Menke 1979).

The genus Lethocerus is known mostly from lentic waters, usually the deep waters of lakes, and rarely from streams and rivers. The genus Diplonychus Laporte is known throughout the Old World tropics and can be very common in quiet bodies of water. Some members of the Western Hemisphere genus Belostoma Latreille are known from the vegetated banks of streams.

Females of the Belostomatinae lay their eggs on the dorsum of males. The eggs are glued to the male who cares for them until they emerge. The eggs are intermittently wetted, exposed to air, and stroked, which maintains gaseous exchange and enhances egg survival (Smith 1976; Menke 1979). The Lethocerinae usually lay their eggs on exposed vegetation. The oviposition behaviour of the Horvathiniinae remains unknown. The respiratory behaviour of belostomatids is similar to that of Nepidae. The straplike abdominal siphons are used to trap air which travels along marginal hairs and is stored in the sub-hemelytral airstore (Parsons 1972). Life history studies of North American belostomatids have been reviewed by Menke (1979). McKeown (1942) has provided anecdotal information on some Australian species.

The Belostomatidae are divided into three subfamilies: Belostomatinae, Horvathiniinae and Lethocorinae (Lauck & Menke 1961; Štys & Jansson 1988). The Belostomatinae are cosmopolitan and comprise six genera: Abedus Stål, Belostoma Latreille, Diplonychus Laporte, Hydrocyrius Spinola, Limnogeton and Weberiella De Carlo. The Horvathiniinae are monogeneric (Horvathinia Montandon, Neotropical Region, nine species). The Lethocerinae are also monogeneric, contain numerous gigantic species, and are most diverse in the tropical Americas (Lauck & Menke 1961). Perez Goodwyn (2006) revised the subfamily Lethocerinae, recognising three genera within it: BenacusStål, KirkaldyiaMontandon, and Lethocerus Mayr. He also provided a key for all species of the subfamily in the same paper.

Larsén (1938) indicated that Belostomatidae and Nepidae are sister groups based on similarities of the genitalia, caudal respiratory appendages and abdominal musculature. This is supported by characters of the head (Spooner 1938), the spermatheca (Pendergrast 1958) and the antennae (Lauck & Menke 1961). China (1955) suggested that the belostomatids arose from an ancestor that had siphon respiration and metathoracic scent glands.

Significant regional taxonomic works include Poisson's (1949) review of the Afrotropical species and De Carlo's (1964) and Froeschner's (1981) treatments of the South American fauna. Polhemus et al. (1988) catalogued the Nearctic fauna andEstevez et al. (2011) revised the New World genus Weberella. Menke (1960) reviewed the Eastern Hemisphere species of Lethocerus, provided a key and checklist, described a new Australian species, L. distinctifemur, and clarified that L. insulanus (Montandon) had been misidentified in Australia as L. indicus.

The Australian fauna includes four species: Diplonychus eques (Dufour), D. plana (Sulzer), and the two Lethocerus species. Polhemus (1994) clarified the identity of D. plana, which was known previously as D. rusticum in the Eastern Hemisphere. He concluded that Nepa rustica Fabricius, 1775 and Nepa rustica Fabricius, 1781 are separate species. Polhemus (pers. comm.) believes that D. plana does not occur in Australia. It is retained in the Catalogue, however, pending a taxonomic revision of the group. Andersen & Weir (2004b) provided a key for the Australian fauna of belostomatides.


General References

Aldrich, J.R. 1988. Chemical ecology of the Heteroptera. Annual Review of Entomology 33: 211-238

Andersen, N.M. & Weir, T.A. 2004. Australian Water Bugs. Their Biology and Identification (Hemiptera-Heteroptera, Gerromorpha & Nepomorpha). Entomonographen Denmark : Apollo Books Vol. 14 344 pp.

China, W.E. 1955. The evolution of water bugs. Bulletin of the National Institute of Sciences of India 7: 91-103

De Carlo, J.A. 1964. Género Lethocerus Mayr (Hemiptera: Belostomatidae). Physis (Buenos Aires) 24(68): 337-350

Estevez, A.L., Inacio R. & Ricardo, J. 2011. Weberiella De Carlo, 1966 (Insecta: Heteroptera: Belostomatidae) revisited: redescription with a key to the genera of Belostomatidae and considerations on back-brooding behaviour. Zoologischer Anzeiger 250(1): 46-54

Froeschner, R.C. 1981. Heteroptera or true bugs of Ecuador: a partial catalog. Smithsonian Contributions to Zoology 1981(322): iv 1-147

Gope, B. & Prasad, B. 1983. Preliminary observations on the nutritional value of some edible insects of Manipur. Journal of Advanced Zoology 4: 55-61

Larsén, O. 1938. Untersuchungen über den Geschlechtsapparat der aquatilen Wanzen. Opuscula Entomologica. Lund Supplement 1: 1-388

Lauck, D.R. & Menke, A.S. 1961. The higher classification of the Belostomatidae (Hemiptera). Annals of the Entomological Society of America 54: 644-657

McKeown, K.C. 1942. Australian insects. The bugs—order Hemiptera-Heteroptera, I. Australian Museum Magazine 8: 27-31

Menke, A.S. 1960. A review of the genus Lethocerus (Hemiptera: Belostomatidae) in the Eastern Hemisphere with the description of a new species from Australia. Australian Journal of Zoology 8: 285-288

Menke, A.S. 1979. Family Belostomatidae—Giant Water Bugs, Electric Light Bugs, Toe Biters. pp. 76-86 in Menke, A.S. (ed.). The Semiaquatic and Aquatic Hemiptera of California (Heteroptera: Hemiptera). Berkeley : University of California Press.

Miller, N.C.E. 1956. The Biology of the Heteroptera. London : Leonard Hill Ltd x 162 pp.

Parsons, M.C. 1972. Respiratory significance of the thoracic and abdominal morphology of Belostoma and Ranatra (Insecta, Heteroptera). Zeitschrift für Morphologie der Tiere 73: 163-194

Pendergrast, J.G. 1957. Studies on the reproductive organs of the Heteroptera with a consideration of their bearing on classification. Transactions of the Royal Entomological Society of London 109: 1-63

Perez Goodwyn, P.J. 2006. Taxonomic revision of the subfamily Lethocerinae Lauck & Menke (Heteroptera: Belostomatidae). Stuttgarter Beiträge zur Naturkunde. Serie A (Biologie) 695: 1-71

Poisson, R. 1949. Exploration du Parc National Albert. Hémiptères aquatiques. Exploration du Parc National de l'Upemba. Mission G. F. de Witte 58: 1-94

Polhemus, J.T. 1994. The identity and synonymy of the Belostomatidae (Heteroptera) of Johann Christian Fabricius 1775–1803. Proceedings of the Entomological Society of Washington 96: 687-695

Polhemus, J.T., Polhemus, D.A. & Henry, T.J. 1988. Family Belostomatidae Leach, 1815: the giant water bugs or electric light bugs. pp. 47-55 in Henry, T.J. & Froeschner, R.C. (eds). Catalog of the Heteroptera, or True Bugs, of Canada and the Continental United States. Leiden : E.J. Brill xix 958 pp.

Rees, A. & Offord, R. 1969. Studies on the protease and other enzymes from the venom of Lethocerus cordofanus. Nature (London) 221: 675-677

Slater, J.A. 1982. Hemiptera. pp. 417-447 in Parker, S.P. (ed.). Synopsis and Classification of Living Organisms. New York : McGraw Hill Book Co.

Smith, R.L. 1976. Brooding behaviour of a male water bug Belostoma flumineum. Journal of the Kansas Entomological Society 49: 333-343

Spooner, C.S. 1938. The phylogeny of the Hemiptera based on a study of the head capsule. Illinois Biological Monographs 16: 1-102

Staddon, B.W. 1971. Metasternal scent glands in Belostomatidae (Heteroptera). Journal of Entomology. Royal Entomological Society of London A 46: 69-71

Štys, P. & Jansson, A. 1988. Check-list of recent family-group and genus-group names of Nepomorpha (Heteroptera) of the world. Acta Entomologica Fennica 50: 1-44

Voelker, J. 1968. Untersuchungen zu Ernährung, Fortpflanzungsbiologie und Entwicklung von Limnogeton fieberi Mayr als Beitrag zur Kenntnis von natürlichen Feinden tropischer Süsswasserschnecken. Entomologische Mitteilungen. Berlin-Dahlem 3: 1-24

Wilson, C.A. 1958. Aquatic and semiaquatic Hemiptera of Mississippi. Tulane Studies in Zoology 6: 115-170


History of changes

Note that this list may be incomplete for dates prior to September 2013.
Published As part of group Action Date Action Type Compiler(s)
30-Nov-2012 30-Nov-2012 MODIFIED
15-Aug-2012 15-Aug-2012 MODIFIED
20-Oct-2010 20-Oct-2010 MODIFIED
12-Feb-2010 (import)