How to Get Rid of Water Bugs in a Pool

What are the water bugs in my pool?

The bugs paddling around your pool are almost certainly water boatmen or backswimmers, two similar-looking aquatic insects that behave very differently. Both are small, oval, and fast, both fly in from nearby ponds and ditches, and both breathe air rather than water, which is why you see them dart to the surface and back down. Telling them apart matters, because one is a nuisance and the other bites.

A water boatman is about a quarter to half an inch long, swims right side up, and rows with oar-like back legs. It feeds on algae and the tiny organic matter in the water, it has no interest in you, and it does not bite. Water boatmen usually show up in numbers, clustered where the algae is, and they are the more common of the two.

A backswimmer looks similar but gives itself away by swimming upside down, on its back. It is a predator that hunts water boatmen, mosquito larvae, and other small creatures, and it will bite if handled or trapped against skin, a sting often compared to a bee, which earns it the nicknames water bee and water wasp. If you have backswimmers, you almost always have water boatmen too, because the boatmen are what the backswimmers came to eat.

Why do I have water bugs in my pool?

You have water bugs because your pool is giving them something to eat. Water boatmen come first, drawn to algae and the microscopic organisms in water that has gone green, dull, or filmy. Even a light bloom you can barely see, or a slick coating on the walls and floor, is enough of a food supply to hold a colony. If the bugs arrived, the water almost certainly has an algae problem worth dealing with first.

Backswimmers follow the boatmen. They are predators, so a pool full of water boatmen is a stocked pantry, and they move in to hunt. That is why backswimmers rarely appear on their own: find them and you can assume the water has been feeding a boatman population, whether or not the pool looks obviously green.

Both bugs are strong fliers that arrive from other water sources, usually at night, and they are drawn to pool lights and to the flat, reflective surface of the water. That is why an outbreak so often appears overnight, right after the water has slipped a little green or after a heavy rain diluted your chlorine. The bugs did not breed in the pool so much as fly to it, following the food and the light.

How do you get rid of water bugs in a pool?

Get rid of water bugs by removing their food source, not by trying to poison the bugs directly. The whole strategy is to take the algae away: clear it, and the boatmen have nothing to eat and the backswimmers have nothing to hunt, so both move on within a few days. Start by shocking the pool and holding a high chlorine level until the algae is gone; the pool shock calculator sizes the dose to your gallons, and the how to get rid of pool algae guide walks the full cleanup.

Brush and vacuum while you clear the water. Brush the walls, floor, and steps to break up algae and biofilm so the chlorine can reach it, and because both bugs lay their eggs on submerged surfaces and in debris, brushing and vacuuming also removes the next generation. A good pool brush makes the job faster, and running the filter continuously keeps the loosened algae and dead bugs moving toward it.

Skim out the adults you can see. The bugs rest at the surface to breathe, so a net pass morning and evening thins them out quickly while the chemistry does the real work underneath. Once the water is clear and balanced, keep the filter running and the free chlorine steady for a few more days; with no algae left, the colony leaves on its own and does not come back as long as the water stays clean.

What kills water bugs in a pool instantly?

Nothing kills water bugs on contact, because both water boatmen and backswimmers breathe air, not water. They carry a bubble of air against their bodies and surface to refill it, so they tolerate chlorinated water far better than you would expect, and shocking the pool does not wipe them out directly. Do not dump extra shock at the bugs hoping they will die in the water; they will not.

The one quick trick people use is a few drops of dish soap spread across the surface. Soap breaks the water's surface tension so the bugs can no longer rest at the top to breathe, and they drown. Treat it as a short-term knockdown, not a cure, and know that soap will foam the water, so keep the how to get rid of pool foam guide handy for clearing that afterward.

Chlorine's real role here is indirect. It does not kill the bugs, but it kills the algae they came to eat, which is the whole point. So shock to clear the algae, use dish soap only if you want to knock down the adults for an afternoon, and let the loss of food, not a chemical, be what actually clears the pool. Keeping free chlorine in range is what makes the fix stick.

Are water bugs in a pool dangerous, and do they bite?

Water boatmen are harmless and do not bite; backswimmers do bite, and it stings like a bee sting, but it is not dangerous for most people. So the honest answer depends on which bug you have, and the swimming direction tells you which one to worry about.

Water boatmen are a nuisance only. They have no bite to defend themselves against people, they do not carry disease that threatens swimmers, and their worst offense is being unpleasant to share a pool with. You can swim with them; most people just would rather not.

Backswimmers are the ones with a painful bite. They have piercing mouthparts built for hunting, and a bite can leave a small welt that is often compared to a bee sting, which is where the water bee nickname comes from. Reactions are usually mild and fade quickly, but anyone with insect-sting allergies should treat a backswimmer bite with the same caution as a bee sting. They do not seek people out; bites happen when one gets trapped against skin, so an unpleasant surprise is the real risk, not a health hazard.

How do you keep water bugs from coming back?

Keep water bugs away by keeping the water clear and the chlorine steady, so there is never any algae to draw them in. There is no additive that repels them and no scent that reliably keeps them out; clean, sanitized water is the only deterrent that works. Hold free chlorine in range for your stabilizer level and test often, and check your numbers against ideal pool chemistry levels so nothing drifts far enough to let algae start.

During an active outbreak, turn the pool lights off at night and cover the pool if you can. The adults fly in after dark and are drawn to light and to the open water surface, so darkening the pool stops new bugs from arriving while you clear the ones already there. This buys you a few quiet nights to finish the job.

After that, it is just routine. Skim daily, brush weekly, run the filter long enough to turn the water over, and keep the chemistry balanced; the pool maintenance schedule lays out exactly what to do and when. A pool that never goes green never has a water-bug problem, because the food never shows up in the first place.

Frequently asked questions