What is serpentine leafminer (SLM)?
Serpentine leafminer (Liriomyza huidobrensis; SLM) is an invasive pest of horticulture and vegetable production systems. Its larvae feed on a wide range of crops, ornamental plants and weeds. As they feed, the larvae create winding tunnels, known as mines, inside the leaves.
SLM attacks more than 200 plant species worldwide. Important hosts include potatoes, beans, peas, brassicas, lettuce, celery, tomatoes, cucurbit crops, nursery plants, cut flowers and ornamental plants.
What are the impacts of SLM?
Heavy infestations can:
reduce plant growth;
reduce crop quality and yield;
increase production costs; and
require additional pest management.
Many common weeds can also host SLM, allowing it to survive between cropping cycles and spread in the wider environment.
SLM in Tasmania
SLM was first detected in Tasmania in June 2026.
Following surveillance and investigations, SLM was found at multiple locations in North West Tasmania and is now considered established in the wider environment.
Biosecurity Tasmania is transitioning its response to long-term management. This decision was made based on current evidence, expert advice, and consultation with industry.
The focus now is on supporting industry-led management, maintaining market access, improving understanding of SLM in Tasmania, and promoting practical measures that minimise pest impacts and slow spread where feasible.
Find out more on the SLM transition to management FAQ page.
Managing SLM
SLM is a pest that can be effectively managed.
Research and experience from Australia and overseas show that the most effective approach combines:
monitoring and early detection;
good farm biosecurity;
integrated pest management (IPM);
appropriate insecticide use; and
protection of beneficial insects and natural enemies.
What growers can do to help manage SLM
Transition to management does not reduce the importance of good property biosecurity.
Growers should continue monitoring crops, maintaining good farm biosecurity and managing pests as part of normal farming operations.
Adult leafminers are typically poor fliers, moving only short distances between crops. The main risk for spread is through human movement of infested plant material and high-risk inputs (e.g. mulch, fill, growing media etc).
To reduce the risk of SLM spreading, growers should:
learn to recognise signs of SLM;
avoid moving potentially infested plant material;
maintain good farm biosecurity practices;
monitor crops and host plants regularly;
manage host weeds;
clean machinery, equipment, vehicles and boots between properties.
The farmbiosecurity.com.au website has the free resources that property owners can use to implement practical farm biosecurity measures.
Identification of serpentine leafminer
Liriomyza huidobrensis (Blanchard, 1926)
Adults
An adult serpentine leafminer (Liriomyza huidobrensis) sitting on a leaf
Photo: Central Science Laboratory, Harpenden , British Crown, Bugwood.org
1-3mm, grey-black flies with yellow markings. Usually there is a prominent yellow area at the base of the wings.
The adults look very similar to other exotic and local Liriomyza flies present in Australia. Reliable identification requires examination under a microscope.
Female flies use their ovipositor to puncture the leaves of host plants and deposit eggs. The eggs are inserted just below the leaf surface. Many eggs may be laid on a single leaf.
Larvae
The larvae are yellow to white in colour and feed in the living plant tissue in tunnels beneath the surface of the plant.
The larvae are small and cannot be easily seen – only the damage on the leaf surface caused by feeding will generally be visible.
Pupae
Serpentine leafminer (Liriomyza huidobrensis) pupae sitting on a damaged leaf
Photo: Merle Shepard, Gerald R.Carner, and P.A.C Ooi, Bugwood.org
Pupae are 1.3 to 2.3 mm, oval shaped and transitioning in colour from pale yellow-orange to a dark golden-brown or black before adult flies emerge.
The pupation site of SLM is outside the leaf mines on the leaf surface or dropping to the soil. If pupae are inside leaf mines, they are likely not SLM.
Damage
 Serpentine leafminer leaf damage
Photo: NSW DPIRD
|  White squiggly tracks on a leaf surface caused by serpentine leafminer (Liriomyza huidobrensis) damage
Photo: Merle Shepard, Gerald R.Carner, and P.A.C Ooi, Bugwood.org
|  White squiggly tracks and brown necrosis on a leaf caused by serpentine leafminer (Liriomyza huidobrensis) damage
Photo: Merle Shepard, Gerald R.Carner, and P.A.C Ooi, Bugwood.org
|
The larvae of all Liriomyza species ‘mine’ the leaves of host plants. The larvae feed by tunnelling through the leaf tissue.
Leafminers leave squiggly white lines on impacted host plants as the larvae tunnel through the leaves.
Heavy tunnelling damage reduces the ability of the plant to photosynthesise, which can result in leaf death, premature leaf drop and secondary infection by pathogens such as Botrytis.
Mine damage can also reduce crop yield and leave leafy green crops unmarketable due to the tunnelling left behind.
Leafminer damage caused by local leafminer species is generally not distinguishable from an exotic leafminer. If you suspect an exotic leafminer infestation you should report it immediately.
Spread
Leafminers are spread through the movement of live host plants containing eggs, larvae, pupae or adults, as well as the movement of pupae via contaminated soil.
Adult leafminers are typically poor fliers, moving only short distances between crops, but can also travel long distances by hitchhiking via human movements or through wind dispersal.
Similar species
Leafminers similar to SLM are very common in Tasmania and entomologists can only make an accurate diagnosis by rearing larvae through to the adult stage or using molecular testing.
Common leafminers in Tasmania include L. chenopodii (beet leafminer), L. brassicae (cabbage leafminer), Chromatomyia syngenesiae (cineraria leafminer) and Scaptomyza flava (turnip leafminer).
Grower resources
Biosecurity Tasmania, AgriGrowth Tasmania and the Tasmanian Institute of Agriculture (TIA) are working with industry to provide growers with practical information and support to help manage SLM in Tasmanian conditions.
TIA will lead a research, extension and industry support program to assist growers and affected industries, including development of Tasmania-specific guidance materials.
Resources on this page will be updated as new information becomes available.
Biosecurity Tasmania SLM info sheet
Information Sheet - Serpentine leafminer (DOCX 219Kb)
AUSVEG SLM grower guides
AUSVEG has a series of leafminer grower guides available. These guides were developed through vegetable industry levy funds following the establishment of SLM on mainland Australia. Although not optimised for Tasmanian conditions, they are still a useful resource for growers.
The AUSVEG guides provide practical information and resources for managing leafminer in vegetables, onions, potatoes and melons:
Hort Innovation management plan
Management plan for leafmining flies in vegetable and nursery crops in Australia. This resource was prepared as part of Hort Innovation project MT16004.
Greenlife Industry Australia management plan
Greenlife Industry Australia has developed a Management Plan for the Australia Nursery Industry.
DARABUG2 pest climate model
This is a simple model for predicting how SLM will progress through its life stages at a given GPS location and time of year. It was developed by James Maino of Cesar Australia.
Note that SLM is listed as “Pea leafminer” in the species dropdown options.
https://cesaraustralia.shinyapps.io/darabug2/