BIOSECURITY UPDATE: American serpentine leafminer

American serpentine leafminer, Liriomyza trifolii, has been found infesting plant hosts in Kununurra, Western Australia in March 2021, and more recently on Thursday Island in the Torres Strait, Queensland in May 2021.

As a National Priority Plant Pest, the American serpentine leafminer poses a serious threat to Australia’s horticulture, nursery production, and agricultural plant industries. Severe infestations of American serpentine leafminer may result in premature leaf drop, poor growth, and reduced crop yields.   

The situation

Since the initial detection, the Northern Australia Quarantine Service (NAQS) has reported multiple detections in the Torres Strait and Kununurra, with further detections found in the Northern Peninsula Area of Cape York Peninsula, Queensland, which are still undergoing confirmatory identification. Surveillance is still being conducted to determine the distribution of this pest in both Western Australia and Queensland.

In July, genetic testing and morphological identification techniques confirmed the species found in Western Australia and Queensland as American serpentine leafminer.

On Monday, 19 July 2021, the Consultative Committee on Emergency Plant Pests (CCEPP) met and declared American serpentine leafminer as an emergency plant pest under the Emergency Plant Pest Response Deed (EPPRD). Further information is required to determine whether it’s technically feasible to eradicate.

About the American serpentine leafminer

The American serpentine leafminer is a pest that is found in greenhouses and warm climates, though may seasonally become a pest in cooler climates.

It is highly polyphagous and has been recorded on 25 plant families, with the most important crops under threat being beans, carrot, celery, Chinese wax gourd, chives, chrysanthemum, cucumber, edible gourds, eggplant, gerbera, gypsophila, hibiscus, lettuce, onion, pea, pepper, potato, pumpkin, spinach, squash, tomato and watermelon.

Figure Caption: Mine in tomato leaf caused by Liriomyza leafminer. Photograph by J. Castner, University of Florida.

Damaged plants commonly have reduced yield and in some cases are completely destroyed. Like many leafminer species, this pest is known to carry and develop insecticide resistance making it difficult to manage.

It has a wide host range of plant species which includes beans, celery, chrysanthemum, cucumber, gerbera, gypsophila, lettuce, onion, potato, tomato, peanuts, soybeans, lentils, lupins, faba beans, chickpeas and many more.

For useful identification information and images, head to:

Photo Credit: Photograph by Lyle J. Buss, University of Florida.

Trade Impacts

There are no expected trade impacts either internationally or domestically, outside of those already in place on plant movement in the Torres Strait and Northern Peninsular Area of Queensland, and potential controls in northern Western Australia.

Report and submit samples

If you detect any signs of leaf mining in host plants, please contact the Exotic Plant Pest Hotline on 1800 084 881 right away – early detection is vital for managing and eradicating pests and disease. Immediate instructions will be given on how to collect and submit samples.

For further information contact National Biosecurity Manager John McDonald via email at

The ‘National biosecurity and sustainable plant production program’ (NY20001) project is funded by Hort Innovation using nursery research and development levy and funds from the Australian Government.