Water Boatman

The Water Boatman is a common aquatic true bug in the family Corixidae, order Hemiptera, well adapted to life beneath the surface of freshwater habitats. Its flattened, streamlined body and long, fringed hind legs, used like oars, make it one of the most efficient swimmers among aquatic insects.

Unlike its lookalike relative the backswimmer, which swims upside down and is predatory, the Water Boatman typically swims right-side up and feeds primarily on algae, detritus, and microorganisms, making it more of a grazer within its aquatic community rather than an active predator.

As both a consumer of algae and detritus and a prey item for fish, amphibians, and aquatic birds, the Water Boatman occupies an important position in freshwater food webs, contributing to nutrient cycling within ponds and slow-moving waters.

• Flattened, elongated oval body, streamlined for swimming, typically 5–15 mm long.
• Coloration generally mottled gray, brown, or olive with fine, dark cross-hatched patterning on the wings.
• Long, flattened, fringed hind legs adapted as swimming oars, held out to the sides.
• Short front legs modified for scooping algae and detritus rather than grasping prey.
• Lookalikes: frequently confused with the backswimmer (Notonecta spp.), which swims upside down and has a more rounded, keeled back; the water boatman swims right-side up and has a flatter back.

Found worldwide in freshwater habitats, water boatmen are common in ponds, lakes, slow streams, and vegetated ditches. They are active throughout the warmer months, often seen resting near the surface or diving to feed among submerged vegetation and sediment, and some species overwinter as adults in the mud at the bottom of water bodies.

Water boatmen swim using their oar-like hind legs, propelling themselves in short bursts through the water, and periodically surface to trap a bubble of air against their body for underwater respiration. They feed primarily on algae, plant detritus, and microorganisms scraped from submerged surfaces using their modified front legs, distinguishing them ecologically from the predatory backswimmer. Some species can produce a soft, chirping sound by rubbing body parts together, a behavior known as stridulation, and adults are capable of flight and often disperse between water bodies, sometimes attracted to lights at night.

Water boatmen undergo incomplete metamorphosis, spending their entire life cycle in or near water. Eggs are laid attached to submerged plants, rocks, or debris, hatching into nymphs that resemble smaller, wingless versions of the adult and grow through several instars while feeding underwater. After their final molt, they emerge as fully winged adults capable of flight and dispersal to new bodies of water. Depending on climate, one to several generations may occur per year, with some species overwintering as adults in bottom sediments.