Serpentine leafminer in Tasmania
Biosecurity Tasmania (BT) is investigating detections of serpentine leafminer (Liriomyza huidobrensis; SLM) in North West Tasmania. SLM is a high-risk invasive pest of horticulture and vegetable production systems.
This is the second confirmed detection of SLM in Tasmania. SLM has been present on mainland Australia since 2020.
BT has put in place site-specific biosecurity directions, at both sites, to control and minimise spread, and is undertaking further surveillance and tracing activities.
Find out more on our SLM detection page.
SLM is classed as Prohibited Matter in Tasmania under the Biosecurity Act 2019.
If you suspect that you may have SLM on your property:
Restrict access to the area and don’t move any plants or plant material off-site.
Note the location and get a photo of the damage and leafminers if you can.
Report it to Biosecurity Tasmania: Phone: 1300 368 550; Email: biosecurity.tasmania@nre.tas.gov.au
What is serpentine leafminer?
SLM is a leafmining fly in the genus Liriomyza that is exotic to Tasmania.
The larvae of this group of flies cause damage to plants by tunnelling through the leaves as they feed – these tunnels cause visible damage known as ‘mines’. High level of infestations can affect the plant’s ability to photosynthesise and reduce growth/yields.
There are over 300 species of Liriomyza worldwide, including species in Australia. A small number of species, including SLM, are considered significant pests that are known to attack a wide variety of plants.
Globally, more than 200 plant species across over 30 plant families have been recorded as hosts of SLM. You can find a host list here.
Major crop hosts include potato, beans, peas, brassicas, lettuce, celery, tomato and cucurbits. It also attacks ornamental plants such as chrysanthemum, gypsophila, ranunculus and other nursery crops. Numerous weed species can act as reservoir hosts, allowing populations to persist between crop cycles.
Because of this broad host range and its capacity for rapid reproduction, SLM is regarded internationally as a high-risk invasive pest of horticulture and vegetable production systems.
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, including SLM, 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).
What you can do
Growers and members of the public should look out for distinctive squiggly white lines on plant leaf surfaces caused by feeding damage from leafminer larvae.
Due to the presence of other leafminers in Tasmania, reporting should be prioritised to the following cases:
Heavy leafminer infestations on commercially grown plants, particularly if the infested plants have not been infested previously.
Plants that are not commonly infested by leafminer species already present in Tasmania, including:
Aster sp. (e.g. daisies)
artichoke
Bellis perennis (lawn daisy)
beans
Calendula sp. (e.g. pot marigold)
carnation
celery
cucumber
coriander
Gladiolus sp.
pumpkin
Ranunculus sp. (e.g. buttercups)
squash
sunflower
Tagetes sp. (e.g. marigold)
Verbena sp.
Viola sp.
zucchini
If you see leafminer damage on these plants, or suspect possible SLM:
Restrict access to the area and don’t move any plants or plant material off-site.
Note the location and get a photo of the damage and leafminers if you can.
Report it to Biosecurity Tasmania: Phone: 1300 368 550; Email: biosecurity.tasmania@nre.tas.gov.au.
Good farm biosecurity helps to prevent the spread of pests, weeds and diseases. Best practice biosecurity actions that growers can take include:
Practise ‘come clean, go clean’
Ensure all staff and visitors understand and follow your property hygiene requirements
Monitor your crops regularly
Monitor and control volunteer plants that can harbour pests
Source plant material from reputable suppliers
Keep records
The farmbiosecurity.com.au website has the free resources that property owners can use to implement practical farm biosecurity measures.