Kanzawa spider mite

Tetranychus kanzawai

This tiny pest damages a range of plants that are important to New Zealand's economy.

About the kanzawa spider mite

The kanzawa spider mite causes damage to plants by feeding on leaves and sometimes fruit. It forms a mass of webbing over leaves and fruit, making it harder for the plant to thrive.

It's the second most damaging spider mite of agricultural crops in Japan. It's a major pest in Southern China and a pest of Taiwan's eggplant and strawberry crops.

It is reported to survive in greenhouses as well as in open fields.

Global distribution of kanzawa spider mite

World map showing distribution of kanzawa spider mite

Why this is a problem for New Zealand

This spider mite has a broad host range, including plants that are important to our economy. The host range includes crops like strawberries, peaches, apples, roses, beans, clover, citrus, cherries, grapes, persimmons, and mulberries.

A mated adult female can survive over the winter nestled in the leaves of a host plant. They give rise to a new generation of mites in the spring and summer. This is one of several traits that help this spider mite survive in a new environment.

Many mite species can quickly become resistant to pesticides, which poses another challenge for controlling this pest.

How it could get here

The mite is most likely to arrive on whole plants and fresh produce. Biosecurity New Zealand has strict measures in place to limit the chances of pests like this making it through the border.

But we need you to be vigilant too. Whenever travelling to New Zealand, always declare any food or plant material in your luggage. If you fail to do so, you could face a $400 fine.

How to identify the spider mite

This mite can be one of several colours:

  • green
  • greenish-cream
  • dark brown to orange.

They are up to 1.5mm long and have 8 legs.

Damaged leaves show yellow spots. A severe infestation can cause the whole leaf to become yellow and dry.

If you think you've found kanzawa spider mite

There are a few mite species in New Zealand already. Identification requires an expert (acarologist). If you're a professional grower, and you are concerned about mites and mite damage that's different from what you're familiar with:

Note: This information is a summary of this pest's global distribution and potential impacts on New Zealand.

Last reviewed: