Breadcrumb navigation

Weed-killing beetles on a mission

Published: 7 December 2015

Tweet this quote Share Share this

Meet nature's weed killers: Agents Shiny, Stripy and Knobbly

Nearly 400 beetles were released into a Birkenhead reserve earlier in December with one mission: take down the aggressive tradescantia weed (commonly known as ‘wandering willie’).

Nicknamed Knobbly, Shiny and Stripy, the three species of beetle each attack a different part of the weed – the stem, the leaf and the tip. They are host-specific, meaning they only attack tradescantia and will starve without it.

This is the first time all three species have been released at a single site in Auckland.

“Tradescantia is a nasty invasive weed that smothers native seedlings and prevents regeneration. It also causes dermatitis in dogs and other animals, so it’s great to have another tool to control it,” says Holly Cox, Auckland Council's Senior Biosecurity Advisor.

Biological control

“The beetles are an example of biological control, which is control using a weed’s natural enemy. It doesn’t eradicate it, but successful biocontrol will weaken a weed and reduce its abundance – making it easier to control with other methods and allowing native species to compete.”

Before being released in New Zealand, a biocontrol agent undergoes extensive research and testing. These beetles were approved for release in 2008 (leaf) and 2011 (tip and stem) and are each present at other Auckland sites.

Kaipātiki Local Board member Danielle Grant is very happy to host the new residents.

“Many local groups and individuals help to control weeds in our parks and on their own land, so it’s great to have nature on our side."

Tiny agents

"Success relies on the beetles becoming well established, so we are keeping the exact location under wraps for our little agents to be left alone to do their work."

Ongoing monitoring of the Birkenhead site will reveal how well Shiny, Stripy and Knobbly work together to help keep tradescantia under control.

If the trial release proves successful, other affected sites may also become home to the weed-killing beetles.


Local board tackles weeds in the Waitākere Ranges

Waitākere Ranges Local Board has launched offensives on several fronts to protect the beautiful Waitākere Ranges rain forest and coastal areas from the threats of damaging weed species.

Introduction to Composting Courses

Learn the basics of composting at home with online and in-person courses.

Top tips to keep dogs safe

Auckland Council encourages the use of positive reinforcement as the best way to train your dog.

Forest flourishes following Hunua pest blitz

Flourishing foliage and signs of new life in the kōkako population are the first signs of a successful pest control programme in the Hunua Ranges this year.

Challenges for Auckland's environment

Auckland Council has now released its state of the environment report, The Health of Auckland’s Natural Environment In 2015.

Auckland free of Queensland fruit fly

MPI has confirmed that Auckland is now free of the Queensland fruit fly.