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Lethocerus americanus in Montana, USA
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hemiptera
Infraorder: Nepomorpha
Family: Belostomatidae
Leach, 1815
Subfamilies and genera







Belostomatidae is a family of freshwater hemipteran insects known as giant water bugs or colloquially as toe-biters, Indian toe-biters, electric-light bugs, alligator ticks, or alligator fleas (in Florida). They are the largest insects in the order Hemiptera, and occur worldwide, with most of the species in North America, South America, Northern Australia, and East Asia. They are typically encountered in freshwater streams and ponds. Most species are at least 2 cm (0.8 in) long, although smaller species also exist. The largest are members of the genus Lethocerus, which can exceed 12 cm (4.5 in) and nearly reach the length of some of the largest beetles in the world.[1][2] Giant water bugs are a popular food in parts of Asia.[3]


Belostomatids typically have an ovular and elongate body, with flattened legs. The hind tarsi have two apical claws and tucked behind the eyes is a short antennae. A short breathing tube is retracted into its abdomen,[4] with a proboscis used to inject powerful saliva into its prey and suck out the liquefied remains.[2] Wings pads can be seen from the dorsal view.


Abedus indentatus , male with eggs on its back

Feeding and defense[edit]

Belostomids are aggressive predators which stalk, capture, and feed on aquatic invertebrates, snails, crustaceans, fish, and amphibians. The largest species have also been found to capture and feed on baby turtles and water snakes.[5] They often lie motionless at the bottom of a body of water, attached to various objects, where they wait for prey to come near. They then strike, injecting a powerful digestive saliva with their rostrum. Although their bite is excruciatingly painful, it is of no medical significance.[6] Adults cannot breathe under water, so must surface periodically for air.[6] Occasionally, when encountered by a larger predator, such as a human, they have been known to "play dead" and emit a fluid from their anus.[6] Due to this, they are assumed dead by humans only to later "come alive" with painful results.[6]


Male (red tag) and female (blue tag) copulating

Belostomatids show paternal care and these aspects have been studied extensively, among others involving the North American Belostoma flumineum and the East Asian Lethocerus (Kirkaldyia) deyrollei. In species of the subfamily Belostomatinae, the eggs are typically laid on the male's wings and carried until they hatch. The male cannot mate during this period. The males invest considerable time and energy in reproduction and females take the role of actively finding males to mate. This role reversal matches the predictions of R. L. Trivers' parental investment theory. In the subfamily Lethocerinae, the eggs are laid on emergent vegetation and guarded by the male.

In Asian cuisine[edit]

Fried giant water bugs at a market in Thailand

In some areas, belostomatids are considered a delicacy, and can be found for sale in markets. This is mainly in South and Southeast Asia involving the species Lethocerus indicus.[3] Elsewhere, species from this genus have been used as food more locally, including by indigenous peoples of Western North America.[3] In South and Southeast Asia they are often collected for this purpose using large floating traps on ponds, set with black lights to attract the bugs. Adults fly at night, like many aquatic insects, and are attracted to lights during the breeding season.


  1. ^ P. J. Perez-Goodwyn (2006). "Taxonomic revision of the subfamily Lethocerinae Lauck & Menke (Heteroptera: Belostomatidae)". Stuttgarter Beiträge zur Naturkunde, Serie A (Biologie). 695: 1–71. 
  2. ^ a b Haddad, V.; Schwartz; Schwartz; Carvalho (2010). "Bites Caused by Giant Water Bugs Belonging to Belostomatidae Family (Hemiptera, Heteroptera) in Humans: A Report of Seven Cases". Wilderness & Environmental Medicine. 21: 130–133. doi:10.1016/j.wem.2010.01.002. 
  3. ^ a b c Mitsuhashi, J. (2017). Edible Insects of the World. CRC Press. ISBN 978-1-4987-5657-0. 
  4. ^ Merritt, R.W. (2008). An Introduction to the Aquatic Insects of North America. Dubuque, Iowa: Kendall/Hunt Company. 
  5. ^ "BBC Nature - Giant water bug photographed devouring baby turtle". BBC Nature. 
  6. ^ a b c d A. C. Huntley (1998). "Lethocerus americanus, the "toe biter"". Dermatology Online Journal. 4 (2): 6. 

Further reading[edit]

  • D. R. Lauck (1962). "A monograph of the genus Belostoma (Hemiptera), Part I. Introduction and B. Dentatum and Subspinosum groups". Bulletin of the Chicago Academy of Sciences. 11 (3): 34–81. 
  • D. R. Lauck (1963). "A monograph of the genus Belostoma (Hemiptera), Part II. B. Aurivillianum, Testaceopallidium, Dilatatum, and Discretum groups". Bulletin of the Chicago Academy of Sciences. 11 (4): 82–101. 
  • D. R. Lauck (1964). "A monograph of the genus Belostoma (Hemiptera, Part III. B. Triangulum, Bergi, Minor, Bifoveolatum, and Flumineum groups". Bulletin of the Chicago Academy of Sciences. 11 (5): 102–154. 
  • A. S. Menke (1960). "A taxonomic study of the genus Abedus Stål (Hemiptera, Belostomatidae)". University of California Publications in Entomology. 16 (8): 393–440. 
  • R. L. Smith (1974). "Life history of Abedus herberti in Central Arizona" (PDF). Psyche. 81 (2): 272–283. doi:10.1155/1974/83959. 
  • R. T. Schuh & J. A. Slater (1995). "True Bugs of the World (Hemiptera:Heteroptera): Classification and Natural History". Cornell University Press. 

External links[edit]