The water boatman is fully capable of flight, a fact that may seem surprising for an insect that spends the vast majority of its life underwater. The water boatman, which belongs to the family Corixidae, is a common aquatic insect found in ponds, lakes, and slow-moving streams across North America. These small, oval-shaped bugs, typically 6 to 12 millimeters long, are air-breathing insects that use their long, oar-like hind legs to propel themselves. Their ability to fly is a crucial survival mechanism that allows them to move between different water bodies.
Environmental Triggers for Flight
Flight for the water boatman is not a daily activity but a temporary behavior driven by specific environmental necessities, often occurring in swarms during the spring and fall. The primary trigger for flight is the search for a new, more sustainable habitat. This migration allows them to disperse and colonize new bodies of water. A common reason for this aerial migration is the risk of desiccation, which occurs when their current pond or stream begins to dry up. To avoid being stranded, they fly to a more permanent body of water. Overcrowding and competition for resources can also prompt a flight response, leading to dispersal flights that reduce population density. Dispersal flights are also undertaken in the late summer and fall to find mates and suitable overwintering sites, often triggered by the first cold snaps of the season. Once airborne, they are often attracted to reflective surfaces, mistaking them for new water sources.
The Mechanics of Taking Off and Flying
The transition from an aquatic to an aerial existence requires a specific preparatory step. Before a flight, the insect must first dry its wings, a process that removes the water film that would inhibit flight. This drying process is a prerequisite for successful takeoff. The wings are typically hidden beneath a protective shell or wing case when the insect is submerged. For flight, these wings must be deployed and utilized by the thoracic flight muscles. Compared to terrestrial insects, the water boatman’s flight is often described as clumsy or erratic, reflecting that their primary adaptations are for rowing, not flying. Once airborne, they are capable fliers, though their goal is usually a direct, purposeful movement toward a new water source. The flight itself is often short-lived, concluding with the insect plunging headlong into the new water body.
Life Beyond the Wing: Aquatic Adaptations
Once the water boatman has completed its migratory flight, it returns to a life specialized for the aquatic environment. The most distinctive feature for movement in water is the pair of long, flattened hind legs, which are fringed with fine hairs, acting like efficient, feathered oars to propel the insect. Unlike their backswimmer cousins, water boatmen typically swim upright, skimming along the bottom. The water boatman does not possess gills, so it must carry its air supply when submerged. It achieves this using a physical gill, or plastron, a thin layer of air trapped against the body by minute, water-repelling hairs. This silvery air bubble allows the insect to breathe underwater, with oxygen transferring from the bubble into the insect’s spiracles. When the oxygen in this bubble is depleted, the water boatman must surface to replenish its air supply, effectively acting like a tiny, self-contained scuba diver. This system of air transport and specialized oar-like legs highlights the water boatman’s primary design as an aquatic organism, with its flight capability serving as a secondary survival trait.