Notonecta undulata

Say, 1832

Grousewinged Backswimmer

Notonecta undulata, commonly known as the grousewinged , is an aquatic true (Hemiptera: Notonectidae) found across North America. measure 10–12 mm in length and are distinguished from other backswimmers by their 4-segmented and wing pattern featuring a large black spot on the wing line. The inhabits small ponds and lakes with slow-moving water, swimming upside down beneath the water surface to capture prey. It is a with documented preference for mosquito larvae, and has been studied as a potential agent.

Notonecta undulata by (c) Dan MacNeal, some rights reserved (CC BY), uploaded by Dan MacNeal. Used under a CC-BY license.

Notonecta undulata by (c) Catherine C. Galley, some rights reserved (CC BY), uploaded by Catherine C. Galley. Used under a CC-BY license.

Pronunciation

How to pronounce Notonecta undulata: /ˌnoʊtəˈnɛktə ˌʌndjʊˈleɪtə/

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Identification

Distinguished from water boatmen (Corixidae) by the segmented (4-segmented) beak and unmodified front legs—water boatmen have highly modified, scoop-shaped front legs. Differs from other Notonecta by the 4-segmented and size (10–12 mm). The wing pattern with a large black spot on the line is also characteristic. The Notonectinae (including N. undulata) is distinguished from Anisopinae by 4-segmented beak and antennae and larger size.

Images

Habitat

Primarily inhabits small ponds and lakes with slow-moving water, though capable of occupying lotic environments including small streams and rivers when resources are limited or competition in lentic is high. Prefers habitats with abundant vegetation providing cover and food resources. Temperature ranges from 4 to 32°C; prefers pH 6.0–7.1. Survives high temperatures temporarily through cuticular lipid monolayer that facilitates water uptake and prevents dehydration.

Distribution

Documented in southern Manitoba, Saskatchewan, Alberta, and the western United States. Broader distribution across North America within the Nearctic region. Records include Vermont and other parts of the United States and Canada.

Seasonality

. First females become and reproductively mature in July, producing a second generation. Adults maturing after July enter reproductive ending by late October. All individuals overwinter as adults. deposition begins in early spring; eggs develop through 5 nymphal instars during spring and summer. Preoviposition period lasts 16 days; 5–14 days. Oviposition is continuous in summer.

Diet

of aquatic and terrestrial prey falling on water surfaces. Documented prey includes small crustaceans, corixid nymphs and , nymphs, , and fish . Shows strong preference for mosquito larvae over other invertebrate prey.

Life Cycle

Hemimetabolous development with 5 nymphal instars. are elongate ovals (1.7 mm × 0.6 mm), attached to plants or suspended objects within the water column. Two per year () with in stage. Reproductive occurs in adults maturing after July.

Behavior

Spends most time at water surface, using and legs to cling to underside of surface tension. Swims upside down to search for prey; stops swimming to float back to surface. Capable of to disperse and seek new ; rate increases with pressure. Maximizes habitat conditions by flying to settle in new areas.

Ecological Role

in aquatic , particularly in lentic environments. Documented to induce morphological and responses in prey (e.g., Daphnia pulex), including reduced body size and altered development through water-borne chemical cues. Potential agent for mosquito due to strong preference for mosquito larvae.

Human Relevance

Suggested as a prudent agent for mosquitoes, including Aedes aegypti, a for and . May be encountered by humans in swimming pools and artificial water bodies. Can deliver painful bites if handled.

Similar Taxa

Corixidae (water boatmen)Superficially similar aquatic , but distinguished by beak to , scoop-shaped modified front legs, and flattened body profile versus triangular cross-section in backswimmers
Other Notonecta speciesN. undulata specifically distinguished by 4-segmented , size (10–12 mm), and wing pattern with large black spot on line

More Details

Taxonomic history

First completely described by H. B. Hungerford in 1917 in the Kansas University Science Bulletin. Taxonomic classification has remained stable for over 40 years, though the remains poorly documented with most scientific literature from the 1920s–1970s and few publications after the 1990s.

Physiological adaptations

Possesses cuticular lipid monolayer that allows water uptake and prevents dehydration during temporary exposure to high temperatures (>32°C). Five attachment points ( legs and ) with associated receptors aid in locomotion and prey capture at the water surface film.