W.A. Pool critters - insect friend or foe?
The Critter Guide: Bugs, Insects & Worms in Your WA Pool
Friend or foe? What these uninvited swimmers reveal about your pool
Living in Western Australia means sharing our outdoor spaces with a remarkable array of wildlife—and sometimes they take a dip in your pool. While finding creepy-crawlies floating in your water isn't exactly pleasant, understanding what they are and why they're there can tell you a lot about your pool's health. Here's your complete guide to the most common pool invaders in Perth and surrounds.
Critters to Remove Immediately
Some pool visitors pose genuine risks—either to your health, your pool equipment, or themselves. These unwanted guests should be removed as soon as you spot them.
Perth's hot summers send wasps and bees searching for water, and your pool is an irresistible oasis. European wasps are particularly aggressive near water sources and can sting multiple times. Native bees, while less aggressive, can still sting when threatened. Use a skimmer net to gently remove them—avoid splashing, which may provoke a sting. Place a shallow dish of water with pebbles away from the pool to give them an alternative drinking spot.
Water Quality Indicator?
Not really—bees and wasps visit pools regardless of water quality. They're simply thirsty, especially during our scorching Perth summers.
Those tiny, wriggling comma-shaped creatures near the surface are mosquito larvae, and finding them in your pool is a red flag. In WA, mosquitoes can carry Ross River virus and Barmah Forest virus, making control essential. Healthy pools with proper chlorine levels rarely have mosquito larvae—they prefer stagnant water. If you spot wrigglers, your sanitiser levels have likely dropped significantly.
Water Quality Indicator?
Yes—a serious one. Mosquito larvae indicate your chlorine or sanitiser level is far too low. Test your water immediately and shock your pool. This is often seen in pools that have been neglected or after extended periods without the pump running.
These aggressive little bugs swim upside-down with their pale belly facing upward, using their long back legs like oars. Unlike their peaceful cousins the water boatmen, backswimmers are predators with a painful bite—often compared to a bee sting. They're attracted to pools with algae and the insects that feed on it. If you're getting bitten while swimming, backswimmers are likely the culprit.
Water Quality Indicator?
Yes. Backswimmers follow their food source. Their presence usually means you have algae growth (even microscopic amounts) attracting smaller insects, which in turn attract backswimmers.
During Perth's dry months, ant colonies send scouts searching for water, and they'll often end up floating in your pool. Coastal brown ants are particularly common in WA. While they're mostly just a nuisance, large numbers can clog skimmer baskets and become unpleasant for swimmers. Keep vegetation trimmed back from your pool edge and address any ant nests nearby.
Water Quality Indicator?
No—ants are simply after water, not attracted by any quality issue. However, cleaning them out regularly prevents debris buildup.
The Friendly Visitors
Not every pool critter deserves the boot. Some are actually harmless indicators that your backyard ecosystem is healthy.
These oval-shaped bugs swim right-side up and are often confused with their bitey relatives, backswimmers. Water boatmen are completely harmless—they don't bite and are actually vegetarian, feeding on algae and plant matter. They're strong fliers and are attracted to lights at night, often landing in illuminated pools. While not harmful, large numbers suggest algae is present.
Water Quality Indicator?
Mild indicator. A few water boatmen are normal, but lots of them suggest algae growth they're feeding on. Check your chlorine levels and brush the pool walls.
Western Australia's garden skinks and small geckos sometimes fall into pools while hunting insects around the edge. These little guys are excellent pest controllers and completely harmless. Unfortunately, they can't climb out of pools easily and will drown if not rescued. Consider installing a Frog Log or Critter Skimmer—a small ramp that lets trapped animals climb out safely.
Water Quality Indicator?
No—skinks are just clumsy hunters who slipped in. Their presence near your pool means you have a healthy garden ecosystem.
WA's native frogs are attracted to pools, especially during breeding season when males are calling for mates. The motorbike frog (named for its engine-like call) and the pobblebonk or Western banjo frog are common visitors. While they're harmless and actually beneficial pest controllers, chlorinated pools aren't great for their sensitive skin. If you find frog eggs, they won't survive in a properly maintained pool.
Water Quality Indicator?
Frogs visiting occasionally is normal. However, if frogs are breeding successfully in your pool (eggs developing into tadpoles), your sanitiser levels are too low.
The Neutral Zone
These visitors aren't dangerous but aren't exactly welcome either. They mostly just need fishing out.
After Perth's winter rains, earthworms often surface and accidentally end up in pools. They're harmless but will die in chlorinated water and can clog filters if numerous. Their presence simply means you have healthy garden soil nearby. Reduce their accidental pool visits by ensuring garden bed edging directs water away from the pool.
Water Quality Indicator?
No—worms in your pool just mean it's been raining and you have healthy soil. They're not attracted by water chemistry issues.
Perth's warm evenings bring moths and various flying insects, many of which are fatally attracted to pool lights. Bogong moths during their migration season can appear in significant numbers. These are simply accidents—the insects are drawn to light, not your pool water. Switching pool lights off when not swimming can reduce the nightly casualty count significantly.
Water Quality Indicator?
No—they're just attracted to the light. However, leaving lots of dead insects in the pool adds organic matter that your chlorine must neutralise.
These slow-moving molluscs occasionally find their way into pools, usually after rain or during their nocturnal wanderings. They're completely harmless but not pleasant to encounter during a swim. Regular pool coping cleaning and trimming overhanging vegetation reduces their access points.
Water Quality Indicator?
No—snails are just slow explorers who made a wrong turn. No reflection on your water quality.
Quick Identification Guide
Spot the Difference: Backswimmer vs Water Boatman
Backswimmer: Swims upside-down (belly up), pale underside visible, pointed body shape, BITES painfully
Water Boatman: Swims right-side up (back visible), darker coloring, more oval shape, completely HARMLESS
Summary: What They Tell You
| Critter | Action | Water Quality Sign? |
|---|---|---|
| Mosquito larvae | Shock pool immediately | ⚠️ Low sanitiser |
| Backswimmers | Remove, treat pool | ⚠️ Algae present |
| Lots of water boatmen | Fish out | ⚠️ Possible algae |
| Tadpoles developing | Remove, check chemistry | ⚠️ Low sanitiser |
| Bees/wasps | Gently remove | ✓ No issue |
| Ants | Skim out | ✓ No issue |
| Earthworms | Fish out | ✓ No issue |
| Moths/flying insects | Skim out | ✓ No issue |
| Frogs (visiting) | Let them leave | ✓ No issue |
| Skinks/lizards | Rescue! | ✓ Healthy garden |
Fun Fact
The water boatman is one of the loudest animals on Earth relative to its body size. Male water boatmen "sing" to attract mates by rubbing their genitalia against their abdomen—producing a sound that can reach 99 decibels. That's roughly as loud as a passing freight train! Thankfully, most of this sound is lost when it travels from water to air, so your pool won't keep the neighbours awake.
Prevention Is Better Than Removal
While you can't keep every critter out of an outdoor pool, you can reduce unwanted visitors significantly. Keep your pool chemistry balanced—most problem insects are attracted to algae, and algae only grows when sanitiser levels drop. Run your pump long enough each day (8-10 hours minimum in Perth summers) to maintain circulation. Trim back overhanging trees and shrubs that provide bridge access for crawling insects. Consider installing a Frog Log or similar escape ramp for accidental visitors. And skim your pool regularly—removing organic matter before it breaks down keeps your water cleaner and less attractive to insects.
Remember, seeing the occasional insect in your pool is completely normal for outdoor pools in Western Australia. It's when certain types appear in numbers, or when species that require stagnant water show up, that you should take notice and test your water chemistry.
Critters Taking Over? We Can Help
If your pool has become a wildlife sanctuary, it might be time for professional attention. Our team can diagnose what's attracting unwanted visitors and get your water back to pristine condition.
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