What is going on with Fall armyworm and Russian wheat aphid in Western Australia?

Key messages

  • Fall armyworm was detected for the first time in Australia in early 2020, migrating from northern Queensland to Kununurra, Broome, Carnarvon, Geraldton and Gingin.
  • Russian wheat aphid was detected in Western Australia for the first time in August 2020 in the Esperance region.
  • Protection from these two new grain crop pests needs to be considered within grain production programs in Western Australia.


To report the geographical range of two pests new to Western Australia (Fall armyworm and Russian wheat aphid) and provide management solutions to grain growers.


The moth/caterpillar fall armyworm was detected for the first time in Australia in early 2020 in northern Queensland migrating through to Kununurra, Broome, and Carnarvon and detected in moth traps at Geraldton and Gingin later in the season. It is reported to feed on more than 350 host plant species, including cotton, maize, rice, sorghum, wheat, fruit and vegetable crops. In addition to cereals, canola and pulse crops, lucerne and C4 grasses are also listed as potential hosts for this species.

Fall armyworm is a highly mobile moth, capable of long distance flights. It is a tropical to sub-tropical pest that does not do well in the cold and so is unlikely to be a serious pest of winter crops in WA. 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 2020 that fall armyworm is not technically feasible to eradicate from Australia.

Similarly, the committee also determined it was not technically feasible or cost-beneficial to eradicate Russian wheat aphid (Diuraphis noxia) (RWA) from Australia. This exotic pest was first discovered in South Australia in 2016 and then subsequently in Victoria, parts of New South Wales and Tasmania. It was detected in WA for the first time in August 2020.

Russian wheat aphid is found in all major grain growing countries where it is a pest of wheat and barley. The main concern regarding RWA is its potential to cause yield loss as unlike other aphids, RWA injects toxins into the plant during feeding that retard growth and lead to yield loss. Crops are most at risk from RWA feeding damage after GS30 (start of stem elongation) until GS50 (start of head emergence).


Fall armyworm

Over 70 pheromone moth traps were established in the WA grainbelt to detect migration of fall armyworm from northern sources such as Carnarvon. The traps were a combination of manual bucket traps (Unitrap®) and automated moth traps (TrapView®) and monitored by DPIRD staff, grower groups and agronomists. Traps were monitored from June to October until crops senesced.

Russian wheat aphid

DPIRD initiated a Level 2 Incident in August 2020, which ran for three months. Field surveillance of wheat and barley crops was conducted by DPIRD staff, growers and agronomists to establish the geographical distribution of RWA.


Fall armyworm surveillance

Although fall armyworm moths were detected at Geraldton and Gingin in 2020, no moths or larvae were detected at grainbelt sites or from public reports of caterpillars via samples or images. Trap sites are presented in Figure. 1. At present, Carnarvon is the most southern point where fall armyworm caterpillars have been confirmed.

P1 Severtson

Figure 1. Manual and automated (TrapView®) fall armyworm moth trapping sites in the WA grainbelt during 2020.

Russian wheat aphid surveillance

A total of 121 sites were surveyed throughout the grainbelt, however RWA was found in 24 sites in the Esperance port zone only (Figure 2). Sites with RWA were located in low, medium and high rainfall areas. RWA was found on early and late-sown barley and wheat crops. Surveys found notably fewer RWA in crops that had an insecticide seed dressing. RWA was present at levels of less than 1% of tillers with RWA, which is well below control thresholds (see GRDC 2020).

P2 Severtson

Figure 2: Localities of surveillance for Russian Wheat Aphid and its presence/absence status


Fall armyworm and Russian wheat aphid are new pests of grain, pasture and horticulture crops in WA. Proper identification, surveillance and an integrated pest management approach will be key in managing these pests going forward.

Although fall armyworm larvae have not been detected in crops or pastures in the WA grainbelt, growers should be vigilant and report suspect caterpillars given their migratory ability over large distances in short periods of time. Identification and management advice (including permitted insecticides for grain crops) can be found at the DPIRD fall armyworm web page: www.agric.wa.gov.au/n/8110.

Although RWA was not found outside of Esperance during 2020, it is highly probable that this pest will migrate from the Esperance port zone. Climatic modelling conducted by Avila et al(2018) predicts that RWA has the potential to persist in all broadacre growing areas of WA. In South Australia, RWA can survive hot dry summers on perennial grasses (Kirkland et al 2019), and higher numbers are found in areas that have had a green bridge for more than eight weeks (van Helden 2021). In WA, surveillance is planned for 2021 to determine the persistence of RWA in Esperance and its presence in the WA grainbelt.


The authors wish to thank the growers, grower groups and agronomists that assisted with RWA surveillance and moth trap surveillance (West Midlands Group, Liebe Group, Mingenew Irwin Group, South Eastern Agronomy Services). Thanks to DPIRD staff Christiaan Valentine, Amber Balfour-Cunningham, Andrea Hills, Joel Kidd and Brent Ladyman for moth trap surveillance. Helen Spafford (DPIRD Kununurra) leads the DPIRD fall armyworm response within DPIRD.


Archer TL and Bynum EO (1992). Economic Injury Level for the Russian Wheat Aphid (Homoptera: Aphididae) on Dryland Winter Wheat. J Econ Entomol 85:987–992. doi: 10.1093/jee/85.3.987

Avila GA, Davidson M, van Helden M and Fagan L (2019). The potential distribution of the Russian wheat aphid (Diuraphis noxia): an updated distribution model including irrigation improves model fit for predicting potential spread. Bulletin of Entomological Research 109, 90–101.  doi: 10.1017/S0007485318000226

GRDC (2020) Russian Wheat Aphid. Available at: https://grdc.com.au/resources-and-publications/resources/russian-wheat-aphid

Kirkland L, Pirtle E, Maino J, Severi J, Lye J, Umina P, Heddle T and van Helden M (2019) Russian wheat aphid - current investigations and recent findings, GRDC Research Update papers  https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2019/02/russian-wheat-aphid-current-investigations-and-recent-findings

van Helden M, Heddle T, Pirtle E, Lye J ,Maino J (2021) Russian wheat aphid thresholds - Insect density, yield impact and control decision making, GRDC Research Update papers

Contact details

Dusty Severtson,
Department of Primary Industries and Regional Development
75 York Rd, Northam WA 6401
08 9690 2160

Svetlana Micic
Department of Primary Industries and Regional Development
444 Albany Why, Albany, WA 6330
08 9892 8591

GRDC Project Code: CES1904-002RTX,