Water boatmen and backswimmers can simply fly into a pool
Water boatmen (Corixidae) and backswimmers (Notonectidae) can fly into outdoor pools, so one or two insects do not mean the water is dirty. If they keep returning, skim them out and check for algae, organic debris, aquatic prey, sanitiser performance and circulation.
Water boatman or backswimmer? How to tell the difference
Both are aquatic true bugs, but their swimming position and feeding behaviour differ. The easiest practical clue is usually how the insect moves through the water.
| Feature | Water boatman | Backswimmer |
|---|---|---|
| Family | Corixidae | Notonectidae |
| Swimming position | Normally swims right-side up. | Characteristically swims upside down. |
| Body and legs | Generally flatter-bodied, with paddle-like hind legs. | Often deeper and more boat-shaped, with long oar-like hind legs. |
| Food | Diet varies by species and can include algae, plant material, organic matter, microorganisms and small aquatic animals. | Predatory and feeds on other small aquatic animals. |
| Handling | Avoid handling unidentified aquatic insects directly. | Some species can inflict a painful stab; use a net rather than handling them. |
Why water boatmen and backswimmers appear in pools
Their presence does not have one single cause. Adults can arrive by flight, while conditions inside or around the pool may make repeated activity more likely.
They can fly into the pool
Both groups can move between bodies of water by flight. A newly arrived insect does not prove that it developed in the pool or that sanitation has failed.
Algae, biofilm and organic material
Some water boatmen use algae, microorganisms or organic material as food. Thin growth on walls, steps or sheltered areas may therefore make a pool more suitable for some species.
Other aquatic organisms
Backswimmers are predators, so aquatic insects and other small organisms can provide prey. Their presence alone, however, does not prove that a prey population is established in the pool.
Algae can establish when sanitation falls behind
If sanitiser is ineffective or repeatedly falls below the pool's needs, algae and biological growth can become established. Confirm this with water testing rather than diagnosing it from insects alone.
Debris can collect in quieter areas
Steps, corners and low-flow sections can collect fine debris or develop surface growth even when the centre of the pool looks clean.
Nearby water and night lighting
Garden ponds, drains and natural water sources can increase the number of aquatic insects nearby. Artificial lighting around the pool may also attract flying insects at night.
Do water boatmen mean the pool is dirty?
No. A water boatman is not a water-quality test.
A clean outdoor pool can still receive flying aquatic insects. Repeated sightings become more useful diagnostically when they occur together with slippery surfaces, algae, cloudiness, accumulated debris or unstable sanitiser readings.
Review water chemistry, clarity, filter condition, pump operation, return flow and any visible algae or debris.
How to remove water boatmen and backswimmers from a pool
Skim the insects out first, then check whether algae, debris or water-care problems are contributing to repeated sightings.
Skim them out
Use a fine pool net to remove visible insects. Avoid handling unidentified aquatic bugs directly.
Remove debris
Empty skimmer and pump baskets, remove leaves and vacuum material from the floor, steps and ledges.
Brush surfaces
Brush walls, steps, corners and low-flow areas to disturb thin algae or biofilm that may not yet be obvious.
Test the water
Check free chlorine, pH and other relevant parameters before deciding whether chemical correction is needed.
Check circulation
Confirm baskets and the filter are serviceable, valves are correctly positioned and return flow is normal.
What if water boatmen appear with algae?
If the insects appear together with green water, slippery surfaces or visible algae, the algae problem becomes the priority.
Test before treating
Confirm sanitiser and pH conditions instead of choosing a chemical dose from appearance alone.
Brush and clean
Remove leaves and debris, then brush affected walls, steps and corners so attached growth can be treated and filtered.
Check filtration
After algae is treated, the loosened material still has to be removed from the water through effective filtration and cleaning.
What not to do
Do not add household detergent
Dishwashing liquid and other household surfactants are not pool-treatment products and can create foam or add unwanted material to the water.
Do not shock the pool just because you saw an insect
A flying bug is not enough information to choose a chlorine dose. Test the water and treat an identified pool problem instead.
Do not handle backswimmers directly
Some backswimmer species can inflict a painful stab if handled or trapped against the skin. Remove them with a net.
Do not rely on skimming alone if they keep returning
Repeated sightings justify checking surfaces, debris, water chemistry and circulation instead of removing insects indefinitely.
How to reduce repeat water boatman and backswimmer problems
Outdoor pools cannot be made completely insect-proof. The practical goal is to maintain conditions that give aquatic insects fewer reasons to remain.
Keep water chemistry stable
Test often enough for the season and pool use so sanitiser and pH remain within the appropriate operating range.
Brush regularly
Pay particular attention to steps, corners, ledges and other areas where thin surface growth can develop.
Remove organic debris
Clear leaves from baskets, the pool floor and sheltered areas before they break down in the water.
Maintain the filter
A dirty or overdue filter can reduce circulation and water clarity even while the pump appears to be operating.
Check low-flow areas
Look for debris or localised growth rather than judging the entire pool only by the clearest section.
Review night lighting
If flying aquatic insects repeatedly arrive after dark, avoid unnecessary bright lighting directly over or beside the water.
Why do the bugs keep coming back?
Recurrence can have two different explanations: new insects may be flying in, or pool conditions may be allowing them to remain for longer.
| What you notice | Possible explanation | What to check |
|---|---|---|
| Occasional insects in otherwise clear water | Adults may simply be arriving from nearby water or surrounding habitat. | Skim them out and confirm normal water readings and clarity. |
| Repeated water boatmen | Food, debris or suitable surface conditions may be present. | Brush surfaces, remove debris and test the water. |
| Insects plus algae or cloudy water | There may be an underlying water-care or filtration problem. | Chemistry, filter condition, circulation and algae treatment. |
| Repeated arrivals after dark | Nearby habitat and artificial lighting may be contributing. | Water remains stable first, then review lighting and the surrounding environment. |
When to have the pool checked
Consider a pool service when insects keep returning together with algae, cloudy water, unstable sanitiser or poor circulation.
Water is cloudy or green
Loss of clarity or visible algae points to a pool condition that needs diagnosis rather than insect removal alone.
Sanitiser readings are unstable
If chlorine repeatedly falls outside the expected range, testing can help identify whether water balance, contamination or treatment demand is contributing.
Circulation appears weak
Weak returns, filter problems, blocked baskets or pump issues can reduce water movement and cleaning performance.
Insects return after normal cleaning
Recurring activity despite routine removal is a good reason to inspect the overall pool condition and surrounding environment.
Related pool care guides and services
Water boatmen and backswimmers in pools FAQ
Are water boatmen dangerous to swimmers?
Backswimmers are the better-known painful-sting risk. If you are not certain which aquatic insect is in the pool, remove it with a net rather than handling it directly.
Do backswimmers bite?
Some backswimmer species can use their piercing mouthparts to inflict a painful stab if handled or trapped against the skin. Use a pool net to remove them.
Does chlorine kill water boatmen and backswimmers?
Do not use chlorine as an insecticide. Physically remove the insects and maintain the pool at its appropriate sanitiser level. Additional chemical treatment should be based on water testing or an identified algae problem.
Should I shock the pool if I find water boatmen?
Not automatically. Water boatmen can fly into otherwise healthy pools. Test the water first and only use additional treatment when the chemistry or pool condition shows that it is needed.
Why do water boatmen or backswimmers keep returning?
They may be arriving again from nearby habitat, or the pool may still contain algae, debris, aquatic organisms or other conditions that make it suitable for longer stays. Check water quality and circulation as well as the surrounding environment.
Recurring pool bugs can be a reason to check the whole pool
If water boatmen or backswimmers keep returning together with algae, cloudy water, unstable chemistry or weak circulation, Litra PoolCare can assess the water and pool condition and identify the practical next step.