Common Name – Backswimmer

Phylum: Arthropoda

Class: Insecta

Order: Hemiptera

Family: Gyrinidae

Notonecta unifasciata, commonly known as the backswimmer, is an aquatic hemipteran insect found in freshwater habitats across North America, including North Dakota. This species is a member of the family Notonectidae and is easily recognized by its habit of swimming upside down just beneath the water surface Backswimmers are predatory insects that feed primarily on other aquatic invertebrates, including mosquito larvae, small crustaceans, and even tadpoles or small fish fry.

They are ambush predators, using their oar-like hind legs to propel themselves swiftly through the water. When prey is detected, N. unifasciata lunges forward and pierces it with its sharp rostrum, injecting digestive enzymes that liquefy the prey’s tissues for ingestion Ecologically, N. unifasciata plays a dual role: it helps control mosquito populations and serves as prey for larger aquatic predators such as fish and amphibians. It is commonly found in ponds, marshes, and slow-moving streams, especially those with abundant aquatic vegetation that provides cover and hunting grounds.

Phenologically, N. unifasciata is most active during the warmer months in North Dakota, typically from late spring through early fall. Adults overwinter in mud or detritus at the bottom of water bodies and emerge in spring to mate and lay eggs. The life cycle includes egg, nymph, and adult stages, with multiple generations possible in a single season depending on temperature and food availability.

Overall, Notonecta unifasciata is a vital component of North Dakota’s aquatic ecosystems, contributing to both predator-prey dynamics and biodiversity.