Giant water bug
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 Abedus indentatus male with eggs on its back
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Giant water bugs are members of the family Belostomatidae within the order Hemiptera, colloquially known as toe-biters. These are the largest insects in the order Hemiptera. They occur worldwide, with most of the species in North America, South America and East Asia. They are typically encountered in freshwater streams and ponds. Most species are relatively large, 2 cm or more, with some of the largest (such as Lethocerus) exceeding 12 cm, and nearly reaching the dimensions (length and mass) of some of the larger beetles in the world. Giant water bugs are a popular food in Thailand.
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[edit] Habits
They are fierce predators which stalk, capture and feed on aquatic crustaceans, fish and amphibians. 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 the strike, injecting a powerful digestive saliva with their mouthparts, and sucking out the liquefied remains. Their bite is considered one of the most painful that can be inflicted by any insect (the infamous Schmidt Sting Pain Index excludes insects other than Hymenoptera); the longer the bug is allowed to inject its saliva, the worse the resulting bite, and as the saliva liquefies muscle tissue, it can in rare instances do permanent damage. Adults cannot breath under water, and must surface periodically for air.[1] 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.[1] Due to this they are assumed dead by humans and others species only to later "come alive" with painful results.[1]
Belostomatids show parental care and the eggs of many species are 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 is predicted by R. L. Trivers' parental investment theory.
In some areas belostomatids are considered a delicacy, and can be found for sale in markets. 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.
[edit] Reproduction
Males attract the females doing a series of periodic movements near water surface generating ripples in the water known as display pumping. Before a female begins ovipositing the eggs, she mates with the male. Then a series of intercalated series of matings and ovipositions occur, females ovipositing 1-4 eggs in each ovipositing bout. An egg batch can have more than 100 eggs so a couple may copulate more than 30 times before female oviposits all the egg batch. This increases male confidence of paternity, a condition thought necessary for the origin of paternal care. There are two substrates of oviposition, females of species pertaining to the ancestral subfamily (Lethocerinae) oviposit on emergent vegetation. On the other hand, Belostomatinae females oviposit on the males' dorsum. The male will raise the eggs exposing them to air periodically to discourage the growth of fungus and maintain the viability of the eggs, or conduct a series of movements below the water known as brood pumping that increases the amount of oxygen diffusion. The eggs will hatch in approximately three weeks but their hatching time will decrease as temperature rise.
[edit] Notes
- ^ a b c Huntley, A. C. (1998) Lethocerus americanus, the "toe biter". Dermatology Online Journal 4(2):6 [1]
[edit] References
- Smith, R. L. (1974) Life history of Abedus herberti in Central Arizona. Psyche 81:272-283 PDF
- Schuh, R. T.; Slater, J. A. (1995) True Bugs of the World (Hemiptera:Heteroptera): Classification and Natural History. USA: Cornell University Press
