Fall armyworm
The fall armyworm (Spodoptera frugiperda) is an exotic pest to Australia.
The National Consultative Committee on Emergency Plant Pests declared that it is not feasible to eradicate fall armyworm (FAW) from Australia and it is now considered established.
Background
FAW originates from the tropical and sub-tropical areas of the Americas. It has been spreading across much of Africa and southern Asia since the first report in Africa 2016.
FAW was detected in 2 locations in northern Queensland, on a maize crop in February 2020.
It is a polyphagous pest and shows preferences for Poaceae, the most common wild and cultivated grasses. These include maize, rice sorghum, and sugarcane.
Impacts
Whilst FAW is a highly mobile insect capable of long-distance flights, the risk depends on the spread of the insect across the continent.
In the United States, FAW is mostly a seasonal migratory pest, which is a good indication for the potential threat to South Australia.
Modelling for FAW (du Plessis et al, 2018) predicts that SA’s climate is only suitable for low population growth, with a growth index of approximately 1 generation. As FAW does not do well in cold environments, it is unlikely that it will be a serious pest for winter cropping.
Global modelling
The below global climate suitability model for FAW was made using CLIMEX, including the spatially-explicit effects of irrigation.
The Ecoclimatic Index (E.I.) describes the potential suitability for persistence, while the Growth index (G.I.) describes suitability for population growth.
Du Plessis, van den Berg, Ota & Kriticos, 2018, Spodoptera frugiperda – CLIMEX modelling., InSTePP Pest Geography, Canberra
Identification
FAW looks like other armyworm species and caterpillars that grow to a similar size of 30 to 40 m, such as budworms and cutworms.
Large FAW can be identified by an inverted ‘Y’ shape on the head capsule and 4 raised spots in a square at the rear.
Insect identification service
Report any unusual sightings of caterpillars using our insect identification service. We can confirm the species of caterpillars and it is free to PestFacts subscribers.
Please note that cannibalism is common for FAW, so if sending more than one, provide a food source in the container with scrunched paper towel to drain moisture, stop mould growing, and provide shelter.
Put specimens in a non-crushable container or cardboard box and use express post at the start of the week. The more individuals the better, we recommend at least 20.