The backswimmer, an aquatic insect belonging to the family Notonectidae, is often found in fresh water environments. This true bug, known scientifically by the genus Notonecta, is a predator in its natural habitat. While not actively aggressive toward people, they will use their specialized mouthparts defensively if they feel trapped or are handled carelessly. The insect’s common name stems from its unique habit of swimming on its back, propelling itself with long, oar-like hind legs.
Understanding the Backswimmer’s Bite
The sensation commonly referred to as a “backswimmer bite” is technically a piercing, as the insect does not use mandibles to chew. Like other true bugs, the backswimmer possesses piercing-sucking mouthparts, known as a rostrum or cylindrical beak, which it uses to subdue its prey. When a person comes into contact with the backswimmer, the insect can insert this sharp structure into the skin.
The immediate and intense pain experienced is the result of the backswimmer injecting its toxic saliva or digestive enzymes. These chemicals are normally used to paralyze and liquefy the internal contents of small prey, such as tadpoles or other aquatic insects. For a human, the reaction is described as a sharp, burning sensation, often compared to the sting of a bee.
This defensive reaction is not medically dangerous to humans, as the amount of injected toxin is small. The pain is intense immediately following the piercing, but it typically subsides within a few hours. The backswimmer only pierces when it perceives a threat, such as being pressed against skin or inadvertently caught in clothing.
Identifying Backswimmers and Their Habitat
Backswimmers are generally small, reaching an adult length of less than one-half inch. They have a streamlined, oval-shaped body that appears somewhat like the keel of an upside-down boat. Their coloration is unique, featuring a light-colored back and a dark belly, which provides camouflage from predators as they swim on their back.
These insects inhabit a variety of still or slow-moving freshwater environments, including ponds, lake edges, slow streams, and ditches. They are also frequently discovered in residential swimming pools, which they may enter after flying. Backswimmers are often confused with the non-biting water boatmen, but the backswimmer’s signature upside-down swimming and its oar-like hind legs differentiate it.
They often rest at the water surface, tilted head-downward, maintaining buoyancy by trapping a thin, silvery air bubble against their abdomen. This constant presence near the water’s surface, or clinging to submerged vegetation, increases the chance of accidental contact with swimmers. Avoiding areas of still, shallow water where these insects are concentrated is the most effective prevention strategy.
Treating the Bite and Recognizing Complications
Immediate care for a backswimmer piercing involves cleaning the affected area thoroughly with soap and water to prevent secondary infection. The intense initial pain and localized swelling can be managed by applying a cold compress or ice pack wrapped in a cloth for 10 to 20 minutes. Elevating the affected limb can also help to reduce swelling.
Over-the-counter treatments can provide relief for residual discomfort and itching. Non-prescription pain relievers, such as acetaminophen or ibuprofen, can be taken for pain. Topical anti-itch creams, like hydrocortisone, or calamine lotion may also be applied to the site.
While a backswimmer piercing is usually a minor local event, it is important to monitor the area for signs of complication. Seek medical attention if you notice signs of an allergic reaction, such as swelling of the face or throat, hives, or difficulty breathing. Persistent or worsening redness, pain, or pus after a day or two could indicate a secondary bacterial infection requiring a doctor’s evaluation.