Local Focus: Leaf, stem and leaf-tip bugs unite in battle against tradescantia weed

They're bugs about the size of a sunflower seed and in the Waikato, bug-hunting biosecurity officers are keen to find them.

The three main species they're looking for are leaf, stem and leaf-tip bugs, all different colours.

"One's bronze, one has yellow stripes and the other is black," Waikato Regional Council Biosecurity Officer, Hamish Hodgson explained to volunteers.

"We're collecting them and then we will transfer them to take them to new sites around the Waikato," Heidi Pene added.

Volunteers being shown how to capture and transport the mitey soldiers. Photo / Hunter Calder

"It would move naturally but it would take a lot longer to do, so we're taking it to areas where people may have requested it."

The leaf bugs were sought after for an important job - feeding on and controlling tradescantia, a weed also known as Wandering Jew or Wandering Willy.

Tradescantia has been under attack since a little beetle with a big name - neolema ogloblini - was introduced several years ago.

"Tradescantia is a pest plant that we are focusing on and it's a ground cover weed and the problem is as you can see, it grows along the ground and smothers other desirable species," Pene said.

"It forms a really dense mat and it's quite difficult to get control of."

Tradescantia came from South America and was a common garden plant when it was first brought to Aotearoa. Now it was a banned pest found in many urban reserves and parks.

Bugs contained and ready to be transported to the next battle zone. Photo / Hunter Calder

"It stops regeneration and basically slowly kills the forest," Hodgson said. "Hopefully, these beetles will eat the Tradescantia so regeneration can occur.

The leaf bugs were introduced to New Zealand seven years ago but they weren't the only weapon against tradescantia. A yellow leaf spot fungus from Brazil was also playing its part after being recently released in the Waikato.

"That fungus has been imported into New Zealand and it has been bred up on tradescantia," Biosecurity officer Richard Gribble said.

"It's another way of weakening the plant and reducing the infestation. The good thing about the fungus is it's got wind-borne spores, so it just relies on the wind to spread it around in an area."

Permission was needed from the Ministry for Primary Industries to introduce the bugs and fungus.

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