WAbedus is a genus of giant water bugs found in freshwater habitats in southern United States, Mexico and Central America. Sometimes called ferocious water bugs, these brown insects typically are between 2.3 and 4 cm (0.9–1.6 in) long, although A. immaculatus only is about 1.3–1.4 cm (0.51–0.55 in), making it the smallest North American belostomatid and possibly worthy of separation in its own genus. Otherwise the different Abedus species are very similar and can often only be separated with a microscope. They will bite in self-defense, which is painful but not dangerous.
WAmbrysus is a genus of creeping water bugs in the family Naucoridae. There are more than 90 described species in Ambrysus.
WAppasus is a genus of giant water bugs found in freshwater habitats in Asia and Africa.
WBelostoma is a genus of insects in the hemipteran family Belostomatidae, known colloquially as giant water bugs. Members of this genus are native to freshwater habitats in the Americas, with the greatest species richness in tropical South America. Most species in the family Belostomatidae have historically been included in Belostoma, but several of these have been moved to other genera.
WBenacus is a genus of giant water bug in the hemipteran family Belostomatidae. Benacus is a monotypic genus, containing a single species, B. griseus, which is found in North America. Benacus was formerly considered a subgenus of Lethocerus.
WCorixa is a genus of aquatic bugs in the family Corixidae. The fossil species C. elegans is from the Rott Formation in Nordrhein-Westfalen.
WGelastocoris is a genus of toad bugs in the family Gelastocoridae. There are more than 20 described species in Gelastocoris.
WLaccotrephes is a genus of water scorpion belonging to the family Nepidae. They are carnivorous insects that hunt near the water surface. They are not aggressive, but may inflict a painful bite if not handled carefully, which may cause a local reaction. There are about 60 species found in shallow stagnant or slow-moving waters in warm parts of Africa, Asia and Australia.
WLethocerus is a genus of the hemipteran family Belostomatidae, known colloquially as giant water bugs, distributed in tropical, subtropical and temperate areas of the world. The greatest diversity of species occurs in the Americas, with only a single species in Europe, two in Africa, two in Australia and three in Asia. It includes the largest true bugs with species capable of reaching a length of over 12 centimetres (4.7 in). The South American L. grandis and L. maximus are the only species to commonly exceed 9 cm (3.5 in), with more typical lengths for the remaining species being between 4.5 and 9 cm. Lethocerus sp. are distinguished from other genera in the Lethocerinae by two symmetrical furrows in the inner pad of setae on the fore femur, the external borders of parasternites II and III narrowed and nearly straight, and with the setae of the tarsomeres following the line of the tibial setae.
WMicronecta is a genus of aquatic insects in the Corixidae family.
WNepa is a genus belonging to the family Nepidae, known as water scorpions. There are six species found in freshwater habitats in the Northern Hemisphere.
WNerthra is a genus of toad bugs in the family Gelastocoridae. There are at least 90 described species in Nerthra.
WNotonecta, or the common backswimmer, is a genus of backswimmer insects in the family Notonectidae. Species in this genus include:Notonecta borealis Notonecta glauca Notonecta hoffmanni Notonecta indica Notonecta insulata Notonecta irrorata Notonecta kirbyi Notonecta lobata Notonecta lunata Notonecta maculata Notonecta marmorea Notonecta meridionalis Notonecta montezuma Notonecta obliqua Notonecta ochrothoe Notonecta pallidula Notonecta petrunkevitchi Notonecta raleighi Notonecta repanda Notonecta shooteri Notonecta spinosa Notonecta uhleri Notonecta undulata Notonecta unifasciata Notonecta viridis
WOchterus is a genus of velvety shore bugs in the family Ochteridae. There are more than 70 described species in Ochterus.
WPelocoris is a genus of creeping water bugs in the family Naucoridae. There are about 15 described species in Pelocoris.
WPleidae, the pygmy backswimmers, is a family of aquatic insects in the order Hemiptera. There are 37 species in three genera, distributed across most of the world, except the polar regions and remote oceanic islands.
WRanatra is a genus of slender predatory insects of the family Nepidae, known as water scorpions or water stick-insects. There are around 100 Ranatra species found in freshwater habitats around the world, both in warm and temperate regions, with the highest diversity in South America and Asia. Fewer are found elsewhere, but include several African, some in North America, three from Australia and three from the Palearctic, notably the relatively well-known European R. linearis.
WSigara is a genus of water boatmen in the family Corixidae. Some species within this genus are halophiles; for example, occurrences of the genus have been noted in the hypersaline Makgadikgadi Pans in Botswana.