Fall armyworm
The exotic pest fall armyworm (FAW), Spodoptera frugiperda, was recently found in a DPIRD surveillance trap in Kununurra. This pest was first detected in Australia in northern Queensland in a maize crop in February 2020 and has since then spread to the Northern Territory and Kununurra. For more information regarding this finding refer to DPIRD’s Invasive pest fall armyworm confirmed in northern Western Australia media statement.
The FAW larvae are a concern to horticultural and grain growers as they can cause significant production losses by feeding on more than 350 plant species, including cotton, maize, rice, sorghum, wheat, fruit and vegetable crops. It is worth noting that in addition to cereals, canola and pulse crops, lucerne and C4 grasses are also listed as potential hosts for this species.
The FAW is a highly mobile insect, capable of long distance flights. It is a tropical to sub-tropical pest which does not do well in the cold and so is unlikely to be a serious pest of winter crops in Western Australia. However, it is possible that the moths may migrate large distances to grainbelt regions when temperatures warm up in spring.
The national technical committee, the Consultative Committee on Emergency Plant Pests, concluded in February that fall armyworm is not technically feasible to eradicate from Australia.
Description
FAW larvae can look similar to other armyworm species and other caterpillars that grow to a similar size (3-4cm), such as Helicoverpa (native budworm) and cutworms.
FAW larvae are light coloured with a larger darker head. As they develop, they become darker with white lengthwise stripes. They also develop dark spots with spines. Larger FAW larvae can be identified by the presence of an inverted ‘Y’ shape on the head and a prominent set of four raised spots on their second last body segment.
The adult moths are 32 to 40mm in length wing tip to wing tip, with a brown or grey forewing and a white hind wing.
Fall armyworm eggs are pale yellow in colour and clustered together in a mass, which often contain 100–200 eggs. Egg masses are usually attached to foliage with a layer of mould or silk-like furry substance.
Fall armyworm take about 2-3 weeks to develop from egg to pupae (depending on temperature), and another 2-3 weeks before moths emerge.
FAW damage in many crops is similar to that caused by other caterpillars. If you find damage symptoms, carefully examine the plants for larvae to identify which species are present.
What should you do if you suspect you have found FAW?
It is important that caterpillars are correctly identified to assist with management decisions. To have your caterpillars identified by DPIRD entomologists take clear close-up photos of the caterpillar and plant damage and submit a report using the PestFax Reporter app.
You can also report any suspect detections of FAW to:
- MyPestGuide (app or online)
- Pest and Disease Information Service (08) 9368 3080
- padis@dpird.wa.gov.au
For more information on FAW refer to;
- DPIRD’s Invasive pest fall armyworm confirmed in northern Western Australia media statement
- DPIRD’s Fall armyworm: declared pest page
- Queensland Department of Agriculture and Fisheries Fall armyworm – should you be concerned? Beatsheet article.
For more information contact Dustin Severtson, Research Scientist, Northam on +61 (0)427 196 656.
Article authors: Cindy Webster (DPIRD Narrogin) and Dusty Severtson (DPIRD Northam).