Beetles are insects that form the order Coleoptera, in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 described species, is the largest of all orders, constituting almost 40% of described insects and 25% of all known animal species; new species are discovered frequently, with estimates suggesting that there are between 0.9 and 2.1 million total species. Found in almost every habitat except the sea and the polar regions, they interact with their ecosystems in several ways: beetles often feed on plants and fungi, break down animal and plant debris, and eat other invertebrates. Some species are serious agricultural pests, such as the Colorado potato beetle, while others such as Coccinellidae eat aphids, scale insects, thrips, and other plant-sucking insects that damage crops.
Spercheus is a genus of aquatic beetles which are placed in a family of their own, Spercheidae within the Hydrophiloidea. About 20 species are known from around the world except the Nearctic with the majority being from the Oriental and Afrotropical Realms.
Tiger beetles are a family of beetles, Cicindelidae, known for their aggressive predatory habits and running speed. The fastest known species of tiger beetle, Rivacindela hudsoni, can run at a speed of 9 km/h, or about 125 body lengths per second. As of 2005, about 2,600 species and subspecies were known, with the richest diversity in the Oriental (Indo-Malayan) region, followed by the Neotropics. While historically treated as a subfamily of ground beetles (Carabidae) under the name Cicindelinae, several studies since 2020 indicated that they should be treated as a family, the Cicindelidae, which are a sister group to Carabidae within the Adephaga.
The whirligig beetles are water beetles, comprising the family Gyrinidae that usually swim on the surface of the water if undisturbed, though they swim underwater when threatened. They get their common name from their habit of swimming rapidly in circles when alarmed, and are also notable for their divided eyes which are believed to enable them to see both above and below water. The family includes some 700 extant species worldwide, in 15 genera, plus a few fossil species. Most species are very similar in general appearance, though they vary in size from perhaps 3 mm to 18 mm in length. They tend to be flattened and rounded in cross section, in plain view as seen from above, and in longitudinal section. In fact their shape is a good first approximation to an ellipsoid, with legs and other appendages fitting closely into a streamlined surface. Whirligig beetles belong to the beetle suborder Adephaga, which also includes ground beetles and diving beetles.
A water beetle is a generalized name for any beetle that is adapted to living in water at any point in its life cycle. Most water beetles can only live in fresh water, with a few marine species that live in the intertidal zone or littoral zone. There are approximately 2000 species of true water beetles native to lands throughout the world.
The Haliplidae are a family of water beetles that swim using an alternating motion of the legs. They are therefore clumsy in water, and prefer to get around by crawling. The family consists of about 200 species in 5 genera, distributed wherever there is freshwater habitat; it is the only extant member of superfamily Haliploidea. They are also known as crawling water beetles or haliplids.
The Adephaga are a suborder of beetles, and with more than 40,000 recorded species in 10 families, the second-largest of the four beetle suborders. Members of this suborder are collectively known as adephagans. The largest family is Carabidae which comprises most of the suborder with over 40,000 species. Adephaga also includes a variety of aquatic beetles, such as predaceous diving beetles and whirligig beetles.
Amphizoa is a genus of aquatic beetles in the suborder Adephaga, placed in its own monogeneric family, Amphizoidae. There are five known species of Amphizoa, three in western North America and two in the eastern Palearctic. They are sometimes referred to by the common name troutstream beetles.
The Dytiscidae – based on the Greek dytikos (δυτικός), "able to dive" – are the predaceous diving beetles, a family of water beetles. They occur in virtually any freshwater habitat around the world, but a few species live among leaf litter. The adults of most are between 1 and 2.5 cm (0.4–1.0 in) long, though much variation is seen between species. The European Dytiscus latissimus and Brazilian Megadytes ducalis are the largest, reaching up to 4.5 cm (1.8 in) and 4.75 cm (1.9 in) respectively. In contrast, the smallest is likely the Australian Limbodessus atypicali of subterranean waters, which only is about 0.9 mm (0.035 in) long. Most are dark brown, blackish, or dark olive in color with golden highlights in some subfamilies. The larvae are commonly known as water tigers due to their voracious appetite. They have short, but sharp mandibles and immediately upon biting, they deliver digestive enzymes into prey to suck their liquefied remains. The family includes more than 4,000 described species in numerous genera.
Calathus is a genus of ground beetle native to the Palearctic, the Near East and North Africa. There are at least 190 described species in Calathus.
Hygrobia is a genus of aquatic beetles native to Europe, North Africa, China and Australia. It is the only genus in the family Hygrobiidae, also known as the Paelobiidae. These are known commonly as squeak beetles or screech-beetles.
Meruidae is a family of aquatic beetles in the suborder Adephaga, with only one genus and species, Meru phyllisae. The beetle species was first found in the early 1980s. and fully described in 2005. At 0.8 mm (0.031 in), it is one of the smallest adephagan beetles in the world. A survey of aquatic beetles of Venezuela indicated that Meru is most common during the wet season, when larger areas of granitic rock surface are covered with water film, which the adult beetles as well as the larvae inhabit.
Copelatus ilybioides is a species of predaceous diving beetle in the family Dytiscidae. It is found in Africa.
Omoglymmius hamatus is a species of beetle in the family Rhysodidae. It was described by John Lawrence LeConte in 1875. Its common name is the wrinkled bark beetle, though this name can refer to the entire family.
Amphizoa lecontei is a species of aquatic beetle. Adults have a body length of between 11.5 and 16 millimeters. Its elytron has a distinct carina on fifth interval. The species is found in western North America, especially in the Rocky Mountains. Its common name is "Trout-stream beetle". Its synonym is Amphizoa carinata.
Anchomenus quadratus is a species of beetle in the family Carabidae. It is found in British Columbia, Canada and the U.S. states such as California, Oregon, and Washington.
Bembidion zephyrum is a species of ground beetle found in British Columbia, Canada and California, Oregon and Washington of the United States.
Amphizoa striata is a species of trout-stream beetle in the family Amphizoidae. It is found in North America. It is between 13 and 15 millimeters long. Its front tarsi have a well-developed groove on the posterior surface and grooves bearing a fringe of long hair-like setae. It lives in British Columbia, Oregon, and Washington.
Promecognathus laevissimus, also known as the smooth millipede hunter, is a species of ground beetle in the family Carabidae. It is found in western North America, including Oregon, California, and Nevada.
Aspidytidae is a family of aquatic beetles of the suborder Adephaga, described in 2002 from specimens in South Africa and China. There are only two known species in the family and these were originally described in the genus Aspidytes, but later the new genus Sinaspidytes was erected for the species found in China. The family can also be referred to by its trivial name cliff water beetles.
