Notonectidae

Latreille, 1802

Backswimmers, Typical Backswimmers

Genus Guides

3

is a of aquatic true bugs in the order Hemiptera, commonly called backswimmers. Members swim upside down (supine) using long, hair-fringed hind legs modified for rowing. The family contains approximately 350 in two : Notonectinae (seven , generally larger) and Anisopinae (four genera, generally smaller). Backswimmers are that actively hunt in open water, and can deliver painful bites with their when handled. They are capable fliers and readily disperse between water bodies.

Notonecta indica by (c) Matthew Pintar, some rights reserved (CC BY), uploaded by Matthew Pintar. Used under a CC-BY license.Buenoa platycnemis by (c) Matthew Pintar, some rights reserved (CC BY), uploaded by Matthew Pintar. Used under a CC-BY license.Buenoa platycnemis by (c) Matthew Pintar, some rights reserved (CC BY), uploaded by Matthew Pintar. Used under a CC-BY license.

Pronunciation

How to pronounce Notonectidae: //ˌnoʊtəˈnɛktɪˌdiː//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from the superficially similar Corixidae (water boatmen) by: (1) swimming posture—backswimmers swim supine (upside down), water boatmen swim prone; (2) body shape—backswimmers have triangular, keel-like cross-section, water boatmen are flattened top-to-bottom; (3) front legs—backswimmers have short, unmodified front legs, water boatmen have scoop-shaped tarsal segments for gathering food; (4) coloration—backswimmers have bold patterning, water boatmen are brown with fine transverse black lines; (5) —backswimmers are active in open water, water boatmen are mostly benthic ; (6) activity—backswimmers are primarily and rarely attracted to lights, water boatmen are frequently attracted to lights at night.

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Habitat

Still freshwater including lakes, ponds, marshes, and wetlands. Frequently colonizes artificial water bodies such as garden ponds, fountains, and swimming pools. Occupies open water column rather than benthic zone. Some in Anisops and Buenoa possess hemoglobin in the , allowing them to regulate buoyancy and remain submerged using oxygen stored in hemoglobin rather than dissolved oxygen.

Distribution

distribution; found on all continents except Antarctica. Present in temperate, tropical, and subtropical regions. Specific records from Europe (including United Kingdom), North America, Brazil (Goiás, Cerrado), Turkey (Van Lake), India (Mysore), and Kenya.

Seasonality

Active during warmer months; can be found year-round in suitable in temperate regions. and activity observed in spring and summer. In temperate regions, likely as adults.

Diet

All members are . Prey includes mosquito larvae, other small aquatic insects, tadpoles, and small fish. Some actively pursue prey in open water.

Life Cycle

Development includes , nymph, and stages. Nymphs resemble adults but lack fully developed wings. No pupal stage (hemimetabolous development). Specific details of egg deposition and nymphal development vary by .

Behavior

Swims upside down using vigorous rowing motions of the hind legs. Surfaces periodically to take in air, aided by hydrophobic hairs on the venter and around the rear end that trap air bubbles. Capable of strong for between water bodies. Primarily ; not attracted to artificial lights at night. When threatened or captured, can deliver a painful stab with the sharp tubular . Some (Anisops, Buenoa) use hemoglobin-derived oxygen to regulate buoyancy and extend submergence time.

Ecological Role

in freshwater , controlling of mosquito larvae and other small aquatic organisms. Serve as prey for larger aquatic predators including fish, amphibians, and aquatic birds. Some used as biological indicators for characterization and water quality assessment. Emission of "predator cues" impairs immune function of mosquito larvae, potentially enhancing effectiveness of agents.

Human Relevance

Can inflict painful bites when handled, often mistaken for stings. Occasionally considered nuisance in swimming pools. Potential value in integrated mosquito management through enhancement of biological —synthetic cues from backswimmers combined with Bacillus thuringiensis israelensis increase mosquito mortality. Used as bioindicator in freshwater assessment.

Similar Taxa

  • Corixidae (water boatmen)Superficially similar body shape and aquatic , but distinguished by swimming posture (prone vs. supine), flattened body, scoop-shaped front , benthic habits, and attraction to lights

Misconceptions

Commonly confused with water boatmen (Corixidae); in the United Kingdom, Notonecta glauca is known as the "greater water boatman," contributing to confusion. Water boatmen do not bite humans; reports of bites from "water boatmen" in pools are almost certainly backswimmers. Backswimmers do not have a stinger—the painful sensation is a piercing bite from the .

More Details

Subfamily distinction

Notonectinae contains seven with generally larger ; Anisopinae contains four genera with generally smaller species. Anisopinae members possess hemoglobin in the for buoyancy regulation.

Buoyancy mechanism

Anisops and Buenoa use hemoglobin-derived oxygen to regulate air bubble size and buoyancy, allowing extended submergence without surfacing.

Secretory structures

Exoskeletal pits on the lateral margins of the pronotum and surface to the scutellum have been identified; these structures appear to be secretory in nature, though their specific function remains unknown.

Sources and further reading