Fighting back against the Queensland pool beetle outbreak

On top of all the other problems Queensland has had to deal with lately, pool owners in the Sunshine State now have to battle an outbreak of small brown bugs.

These bugs are commonly called water beetles, but are more accurately known as Cybister tripunctatus and are a part of the Dytiscidae family. They are similar to “boatmen” and have been found in large numbers in Queensland swimming pools from the Gold Coast to the Sunshine Coast.

These insects prefer habitats of slow-moving or stagnant water. Usually confined to the Murray-Darling basin, they fly about at night looking for the reflection of water to establish a new habitat.

The most likely cause of these beetles breeding in such large numbers is a direct consequence of the unusual weather conditions that has resulted in excess of water across the region. This has led to these insects being able to breed and easily move from one habitat to another, using the excess water as “stepping stones”. Although they are not dangerous, they do have small pincers and can bite.

Currently, there is no complete and effective way to prevent these bugs from getting into the pool, but there are steps that can be taken to try to limit their numbers as well as treatment once they are in the pool water.

BioGuard Education Officer Bill Mansfield has put together some information to help control the beetles.

Prevention

Pool covers: Water beetles fly at night and look for the reflection of water to land in. If the owner uses the pool cover at night, this will greatly reduce the reflection of the pool surface – resulting in far fewer beetles in the pool.

Outside light: These insects are also attracted to light, so by turning off the outdoor lights around the pool area, it should also reduce the number of beetles that end up in the pool.

Treatment

Water beetles require air to survive. They go to the surface to gather air, which they store under their wing covers. As such, the best treatment to eradicate these bugs from your pool is to use a quat-based swimming pool algaecide that breaks the surface tension of the water, while preventing algae growth from the dead insects. This will stop insects from holding onto air while swimming. Hence, the insects will drown and drop to the bottom where the pool vacuum can remove them.

This will remove the insects from your water but until they stop breeding and spreading, this will only be a treatment to remove them after arrival. Prevention is always better than cure.

BioGuard wanted to mention that the bugs were identified by Lianne from Marina Pools, Mount Gravatt.

For more information call BioGuard in Australia on 1800 635 743 or in New Zealand on 0800 441 662.