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About the serpentine leafminer

The maggot (fly larva) of this insect could attack many plants important to New Zealand's horticulture industry and home gardeners.

While a native to South America, this fly has spread almost all over the world. It can be found in:

  • Asia
  • Europe
  • Africa
  • Canada.

Global distribution of serpentine leafminer 

World map showing distribution of serpentine leafminer

Why this is a problem for New Zealand?

The fly's larvae 'mine' into leaves, disfiguring them. This damage reduces the plant's productivity. In small and young plants, the damage can slow the plant's development or kill it.

The serpentine leafminer can be hard to control because it quickly develops resistance to common pesticides.

How could it get here?

The serpentine leafminer could hide in fresh cut flowers, nursery stock, and fresh produce imported to New Zealand.

MPI has strict measures in place to limit the chances of the serpentine leaf miner making it through the border.

Map of New Zealand showing where serpentine leafminer could establish

Where would I find it?

The fly is active during warm seasons. It can remain active during winter in glasshouses.

How to identify the serpentine leafminer

Other species of leafminer are present in New Zealand. The key difference is the 'snakelike' and irregular shape of the damage done to leaves.

leaf with squiggly trails of damage on surface black fly on a leaf with yellow markings on its head and body female leafminer users her ovipositer to puncture the surface of a potato
Left: Leaf showing damage from maggots. Image: under fair use from Wisconsin Horticulture
Middle: An adult serpentine leafminer. Image: Creative Commons from Bugwood
Right: An adult female serpentine leafminer. Image: Creative Commons from Hasan Sungur Civelek

 

The adult flies are small and dark. They grow to only 1.3mm to 2.3 mm long. They have bright yellow areas on their head and in the middle of their body.

You may see the maggots (larvae) on leaves. They grow up to 3.2mm long. They start out colourless then turn pale yellow-orange.

If you've found the serpentine leafminer

  • photograph it (or its damage)
  • collect it (the fly or the leaf)
  • call us on 0800 80 99 66

Note: This information is a summary of the serpentine leafminer's global distribution and potential impacts to New Zealand.

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