Fall armyworm

Fall armyworm (FAW, Spodoptera frugiperda) is an exotic pest that was first detected on the Australian mainland  in February 2020. It has since been been detected in the Northern Territory, northern Western Australia and northern New South Wales. Eradication has been determined to be unfeasible and it is now classified as an endemic pest.

On this page:

See also the FAW pheromone trapping network page.

Identification

Many leaf-eating caterpillars share similar visual characteristics and damage symptoms. FAW larvae are most distinctive when fully grown; distinguishing younger larvae can be more difficult. It is important to not rely on a single characteristic when identifying larvae – a correct identification is more likely when multiple characteristics are considered.

Download Identifying armyworm larvae (May 2020 – 4MB A3 pdf)
Download a Fall armyworm diagnostics presentation by Mark Schutze (DAF, Plant Biosecurity Laboratory) – 2MB pdf
Where live insect collection is impractical, high quality photos, including close-ups are essential to provide the best chance of identifying the specimen. Download a Caterpillar identification: taking photos factsheet (600kB PDF).
The FAW pheromone traps currently used have the potential to attract a range of insects.

Damage

How do FAW and other caterpillars eat holes in leaves without being seen? Take a look at our short video below on FAW shotgun damage in maize.


Management

At this stage, management suggestions are based on overseas information since how FAW will manifest as a pest species under Australian conditions is currently unknown. More detailed information will be made available as we lean more about this pest, its behaviour and impacts under local cropping systems.

See our Beatsheet article Fall armyworm – should you be concerned?  (5 March) for more details.

Thresholds based on overseas data:

Crop Threshold Notes
Maize vegetative

 

Maize whorl stage

3 or more larvae per plant
*50% of plants with fresh feeding20% of plants with one or more larvae
*>75% of plants with feeding
Based on US recommendations:
*Purdue UniversityNeed to consider economics of control i.e. $/ha to treat vs potential yield loss ($/ha).
Sweet corn
Tassel emergence
15% of infested plants US recommendations:
If necessary, control at tassel emergence is more effective than applications in the vegetative stages.
Sorghum vegetative

Sorghum grain fill

30% defoliation, or
>2 larvae per whorl

Use helicoverpa threshold calculator

Based on US recommendations.

Damage at grain fill equivalent to Helicoverpa.

Cotton Monitor crops for leaf damage and fruiting site feeding. Bollgard 3 will incidentally suppress FAW.
Soybeans vegetative

Soybean budding-podding

33% defoliation

3/m2

Based on S. litura (DAF)
Pasture (hay production only) 2-3 larvae /sq foot No permits currently.

Armyworm outbreaks (other species) not uncommon.

FAW presentations

PowerPoint presentations displayed as slideshows.

Webinars

  • Melina Miles was part of a GRDC update FAW webinar on 12 November 2020. You can listen to the recording and read the Update paper at the GRDC website.
  • Online presentation and Q&A session (6 May 2020) featuring Melina Miles (DAF) and Brent Wilson (Nutrien Ag Solutions, Home Hill). Download the Q&A summary (775kB pdf)
  • Fall armyworm was also discussed in an online Seasonal Update on 27 May 2020.

See also our presentations page for more information and links to recordings.

Other resources

The GRDC has a Fall armyworm: a crop invader on the march page with identification information and links to other resources.

The DARABUG insect development model provides a convenient and readily available means of predicting development times using different insect models, including FAW. Gridded climatic data of daily temperatures is used to generate estimates of the dates of occurrence for each stage throughout the whole life-cycle of an insect.

Queensland’s Department of Agriculture and Fisheries (DAF) has a range of crop-specific factsheets.

CropLife Australia has released a FAW resistance strategy.

CottonInfo has a short video highlighting some of the similar characteristics between caterpillars and an Endemics to exotics factsheet that looks at some of the differences between armyworm species found in the tropics.

The Plant Biosecurity Research Initiative has published a fall armyworm continuity plan and is producing a podcast series on FAW. It explores the experiences and observations of experts from around the globe and here in Australia. Visit the PHA website.

A range of spray permits for fall armyworm are now available. Search for permits relevant to your crop/situation at the APVMA website.