''Notonecta undulata'', also known by the common name grousewinged backswimmer, are from the family

Notonectidae Notonectidae is a cosmopolitan family of aquatic insects in the order Hemiptera, commonly called backswimmers because they swim "upside down" (inverted). They are all predators and typically range from in length. They are similar in appearance t ...

and the insect suborder

Heteroptera The Heteroptera are a group of about 40,000 species of insects in the order Hemiptera. They are sometimes called "true bugs", though that name more commonly refers to the Hemiptera as a whole. "Typical bugs" might be used as a more unequivocal al ...

. They are a type of hemipteran or

true bug Hemiptera (; ) is an order of insects, commonly called true bugs, comprising over 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from to around ...

. These aquatic insects typically spend their time at the water's surface, using their abdomen and legs to cling to the underside of the

surface tension Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension is what allows objects with a higher density than water such as razor blades and insects (e.g. water striders) to f ...

. The Grousewinged backswimmer can be found in both lotic and

lentic A lake ecosystem or lacustrine ecosystem includes biotic component, biotic (living) plants, animals and micro-organisms, as well as abiotic component, abiotic (non-living) physical and chemical interactions. Lake ecosystems are a prime example ...

environments; however, they typically prefer small ponds and lakes where the water is slow-moving with less current. They swim upside down looking for prey. Once they stop swimming they float back up to the surface. These insects can be distinguished from water boatman or

Corixidae Corixidae is a family of aquatic insects in the order Hemiptera. They are found worldwide in virtually any freshwater habitat and a few species live in saline water. There are about 500 known species worldwide, in 55 genera, including the genus ' ...

by their segmented beak and front legs. Water boatman have highly modified front legs whereas backswimmers do not. Backswimmers are distributed across a broad range throughout

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

. However, the species ''Notonecta undulata'' has only been documented and studied in southern

Manitoba Manitoba ( ) is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population o ...

Saskatchewan Saskatchewan ( ; ) is a Provinces and territories of Canada, province in Western Canada, western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and on t ...

Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...

and the western United States. ''N. undulata'' differs from other backswimmers by their antennae and size. They are approximately 10–12 mm long, and their antennae are 4 segmented.

Taxonomy and morphology

''Notonecta undulata'' is the Linnaean name for the grousewinged backswimmer. This species is classified as a true bug under the suborder Heteroptera. They are located under the family Notonectidae, which is divided into two subfamilies: Notonectinae and Anisopinae. Individuals that are in the subfamily Notonectinae are distinguishable from their Anisopinae relatives by their 4-segmented beak and antennae. Insects from the subfamily Notonectinae are also larger, approximately 10–16 mm in length. ''N. undulata'' measure 10–12 mm. Grousewinged backswimmers can range from a dull greenish yellow to black. The head of back is convex and the antennae are short and concealed beneath the eye. The scutellum is usually black with pale spots on the sides and at the apex. The hind

tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...

e and tarsus have dense bristle like hairs that make them appear oar-like. This allows them to be efficient swimmers; however, it has been documented that members of the genus ''Notonecta'' are not as good at swimming as ''Buenoa'' sp. The front and middle tarsi have apical claws; however, the hind tarsi are clawless. There are 5 points on the backswimmer that allow it to attach to the surface film of the water. These 5 points include the anterior legs and the abdomen of the insect. There are receptors associated with each of these points that help the insect in locomotion and capturing prey. Grousewinged backswimmers also lack

ocelli A simple eye (sometimes called a pigment pit) refers to a form of eye or an optical arrangement composed of a single lens and without an elaborate retina such as occurs in most vertebrates. In this sense "simple eye" is distinct from a multi-l ...

. The need to detect light was mostly likely lost through natural selection due to a variety of environmental pressures. Their beak is stout and the

ventral Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Th ...

surface of the abdomen has a prominent hairy keel. The front and middle legs are approximately one half shorter than the hind legs and the

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with ...

is enlarged basally. The wing membrane also has a large black spot on the median line and the hemelytra are pale. Prior to 1917, there had been no complete description of the ''Notonecta''

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

until H. B. Hungerford described the species ''N. undulata'' under the ''Kansas University Science Bulletin''. Today, the species ''N. undulata'' is not well documented. Scientific literature and taxonomy referenced range between the 1920s and 1970s, with only a few articles published after the 1990s. Taxonomic classification of the species remains similar today as it did 40 years ago.

Habitat and ecology

''N. undulata'' typically inhabit ponds and lakes but have been known to occupy small streams or rivers when resources become limited or competition in lentic environments is too high. Backswimmers will maximize conditions by flying and seeking out areas to settle. It has also been tested that the Grousewinged backswimmer will have a higher dispersal rate when predation levels increase in the environment. Ponds have a greater surface area to volume ratio of vegetation than lakes which increases the amount of hiding places and food for the insect. This makes ponds one of the best locations for the backswimmer. These insects may prefer ponds because the distribution of ''N. undualata'' depends on food supply. It has been found that ponds and

wetlands A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The ...

have a higher diversity of organisms which is often related to nutrient and food resources. Temperature can also affect the distribution of Grousewinged backswimmers. Scientific study has shown that ''N. undulata'' is capable of surviving over a wide range of temperatures and conditions. They have been known to withstand temperatures ranging from 4 to 32 °C and water hardness between 28 and 220 ppm. In nature, they will avoid temperatures higher than 32 °C by flying and searching out new locations; however, they can withstand them for short periods of time through the use of their cuticular

lipid Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include ...

monolayer A monolayer is a single, closely packed layer of atoms, molecules, or cells. In some cases it is referred to as a self-assembled monolayer. Monolayers of layered crystals like graphene and molybdenum disulfide are generally called 2D materials. ...

. This physiological adaptation allows them to uptake water and avoid dehydration when temperatures get too high. The pH level of water can also affect the backswimmer's choice of habitat or

niche Niche may refer to: Science *Developmental niche, a concept for understanding the cultural context of child development *Ecological niche, a term describing the relational position of an organism's species *Niche differentiation, in ecology, the ...

. ''N. undulata'' has been documented to prefer pH levels between 6.0 and 7.1, a relatively normal water acidity. Environmental factors such as pH, temperature and trophic interactions affect the ecology of the Grousewinged backswimmer. Predator prey interactions are another factor affecting backswimmer ecology. ''Notonecta'' are generalist predators that attack and consume many types of aquatic invertebrates and terrestrial prey that fall on the surface of the water. They are known to prey on small

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

s, nymphs and adults of corixids, dragonfly nymphs,

caddisflies The caddisflies, or order Trichoptera, are a group of insects with aquatic larvae and terrestrial adults. There are approximately 14,500 described species, most of which can be divided into the suborders Integripalpia and Annulipalpia on the b ...

and fish eggs. Specifically, ''N. undulata'' prefers to eat mosquito larvae over any other type of invertebrate. Studies have been conducted between the Grousewinged backswimmer and ''

Aedes aegypti ''Aedes aegypti'', the yellow fever mosquito, is a mosquito that can spread dengue fever, chikungunya, Zika fever, Mayaro and yellow fever viruses, and other disease agents. The mosquito can be recognized by black and white markings on its legs ...

'', a type of mosquito that has been known to act as a vector for

malaria Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or death. S ...

and

yellow fever Yellow fever is a viral disease of typically short duration. In most cases, symptoms include fever, chills, loss of appetite, nausea, muscle pains – particularly in the back – and headaches. Symptoms typically improve within five days. In ...

. As a consequence, ''N. undulata'' has been suggested as a prudent

biological control Biological control or biocontrol is a method of controlling pests, such as insects, mites, weeds, and plant diseases, using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also invo ...

Reproduction

The grousewinged backswimmer is

bivoltine Voltinism is a term used in biology to indicate the number of broods or generations of an organism in a year. The term is most often applied to insects, and is particularly in use in sericulture, where silkworm varieties vary in their voltinism. ...

. Females of the first generation become adults and reproductively mature in July producing a second generation. The adults that become mature after July enter reproductive diapause which ends by late October. All ''N. undulata'' will overwinter in the adult stage and begin depositing eggs in the early spring. Eggs develop through 5 nymphal

instars An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ass ...

during the spring and summer. The preoviposition period lasts 16 days and eggs tend to be laid in ponds or calmer lakes rather than fast-flowing streams. The eggs are attached to plants or other suspended objects within the water column. They are elongate ovals, usually 1.7 mm x 0.6 mm. The incubation period lasts 5–14 days and oviposition is continuous in summer.

References

{{Taxonbar, from=Q10603680 Notonecta Hemiptera of North America Insects described in 1832