Grousewinged Backswimmer

***Notonecta undulata***, also known by the common name **grousewinged backswimmer**, are from the family Notonectidae and the insect suborder Heteroptera. They are a type of hemipteran or true bug. 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. The Grousewinged backswimmer can be found in both lotic and lentic 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 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. However, the species *Notonecta undulata* has only been documented and studied in southern Manitoba, Saskatchewan, Alberta 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.

## Description

*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 tibiae 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. 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 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 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 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.

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