A pool with moving, properly chlorinated water is not a good place for mosquitoes to breed: their larvae need still water. Mosquitoes usually breed around the pool, in water that sits stagnant. The other bugs arrive at night, drawn by the light and the water, and fall in.
Where mosquitoes breed
The usual suspects
| Bug | What it is | Does it bite? |
|---|---|---|
| Mosquito | Lays eggs in still water; its larvae wriggle in a zigzag. | Yes. The tiger mosquito, increasingly widespread in Spain, also bites by day. |
| Backswimmer | An aquatic insect that swims upside down and hunts other insects. | It can give a painful jab if handled. |
| Water strider | Walks on the surface without sinking. | No. |
| Water beetles | Fly in at night, drawn by the light. | Usually not. |
Lots of backswimmers usually means they're finding food: other insects falling into the water. If you remove the insects daily, they leave too.
Where mosquitoes really breed
- Water that collects on the winter cover: the perfect spot. Remove it with a small pump or a rubber squeegee.
- A pool left standing without filtration or chlorine, in spring or after being abandoned.
- Buckets, plant saucers, toys and gutters around the pool holding rain or irrigation water.
- The outdoor shower or a drain that doesn't empty properly.
What to do
- Keep the filtration running every day and free chlorine at 0.5-2.0 ppm.
- Skim the surface every morning and empty the skimmer baskets.
- Turn off the pool lights when not in use: they attract flying insects at night.
- Cover the pool at night if you have a blanket or cover.
- Check the garden once a week for standing water and empty it.
- In winter, if the pool is winterised, keep checking the water on the cover and the winter treatment.
Frequently asked questions
Can mosquitoes breed in my pool?
In a pool that filters daily and has chlorine, it's very difficult. The risk appears when it's standing unused, untreated, or in the water collecting on the cover.
What do I do about backswimmers?
Remove them with the net and take out the insects that fall in every day: with nothing to eat, they stop coming. Avoid picking them up by hand, as they can bite.
Do pool lights attract bugs?
Yes, many flying insects head for light at night and end up in the water. Switch them off when not in use.