Salvinia weevils released in Tallow Creek catchment to control weed

Published on 16 December 2021

Byron Shire Council and Rous County Council have released Salvinia weevils into the Tallow Creek catchment as a biological control for the invasive Salvinia weed.

Salvinia weed, also known as Salvinia molesta, grows very quickly and can double in size every couple of days, taking over waterways and lowering oxygen levels in water that fish need to breath.

The Salvinia weevil is bred by the NSW Department of Primary Industries (DPI) in Grafton as a biological control and natural alternative to chemical spraying.

Each female weevil is capable of laying 300 eggs and both the adult and larval stages of the weevil lifecycle help to kill the Salvinia plant.

The weevils do not feed on native plant species and when there is no Salvinia left the weevils will die.

Orla Seccull, Council’s Coastal and Estuary Officer, said weevils have proven to be an effective control however they are not a quick fix, often taking many months for results to be seen.

“In 2019 we released weevils into the lake at Waterlily Park at Ocean Shores and they successfully reduced a Salvinia infestation to very low levels which allowed for the growth of a native aquatic plant,” Ms Seccull said.

“We strategically released the weevils into an upstream location of Tallow Creek with lots of green growth in the hope that this will provide a good habitat for them to reproduce and create a colony.

“The recent opening of Tallow Creek, saw some of the weed washed into the ocean and we know that this species does not like the salt water which is good news,” she said.

Council will continue to monitor Tallow Creek, by checking the Salvinia for any signs of bug activity like brown or damaged new growth buds.

“The weevil was a great success at Waterlily Park but this does not mean it will work as well at Tallow Creek and it if doesn't we will reassess the situation,” Ms Seccull said.

“We will have to wait and see if they will do their job in their new home in Tallow Creek,” she said.

“With the holidays about to start it’s a timely reminder for people to check equipment like kayaks and stand-up paddleboards because this is often how Salvinia is introduced to waterways.

“And people should never throw any weeds from fishponds or tanks into waterways either,” Ms Seccull said.

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