Current locust situation

Widespread low-medium density nymphs presented in the southern part of inland eastern Australia with frequent small bands identified in early spring. This nymphal population resulted from markedly increased autumn adults developed after record rainfall over the arid interior during February and March, and favourable habitat conditions produced from above average rainfall during late autumn and winter. 

The redistribution of autumn adults in a large scale produced this widespread spring nymphal population. Locust swarms were first observed in the Flinders district of South Australia in late April. This population then migrated south-eastwards into the Riverland, and eastwards into the Mallee of Victoria, the northern Riverina and Central West of New South Wales within one week. Several egg-beds were discovered in the Flinders by the Department of Primary Industries and Regions South Australia (PIRSA) and in the Mallee by Agriculture Victoria. Large numbers of nymphs commenced hatching in the south of these regions from late September onwards, while some adults had already emerged from overwintering nymphs in the far southwest of Queensland. Numerous small bands were reported by the public from these regions and confirmed by ground survey conducted by PIRSA, the Local Land Services (LLS) of NSW, Agriculture Victoria and APLC. However, the aerial survey conducted by both APLC and LLS did not detect any large-scale bands that would warrant an aerial control campaign over the Flinders and Riverland of SA, the Mallee of Victoria, and the Western and Central West districts of NSW in past two weeks. Early instars in lower-density banding and dense vegetation impeded the band visibility from the air in most locations. Nevertheless, PIRSA conducted aerial control over 200 km2 in the Flinders with the assistance of ground marking in early October, and NSW LLS had supplied pesticides to the properties where locust bands were confirmed for ground control. 

Although rainfall totals for September were nil over much of the arid interior, 10 – 25 mm of rainfall (still at below average to very much below average levels) was received in much of the Riverland, Mallee and Riverina areas, and habitat conditions had remained favourable for locust breeding from previous good rains. Warmer temperatures at above average to very much above average levels during autumn and winter enabled prolonged adult activity and improved survival rates of overwintering adults and nymphs. Despite a strongest El Niño is currently underway since 1950s, with a likely positive Indian Ocean Dipole and neutral Southern Annular Mode index, the forecast for average October rainfall and above average rainfall for November and December by the Bureau of Meteorology should produce some favourable habitats for summer generation of locust breeding in the arid interior. 

The overall outlook is for some medium-high density nymphs developing in the southern part of inland eastern Australia with bands to form under warm weather throughout October. Swarms are likely to develop from late-October onwards and migrations under suitable weather systems can begin from early November. If migrating swarms find suitable areas of high rainfall there will be an increased probability of a large summer generation developing in inland eastern Australia.

There is a moderate-high likelihood of a widespread infestation developing for the remainder of spring. 

The overall population likely remained at low-medium levels across inland eastern Australia with higher numbers in the Central West district of Queensland. Survey identified consistent adults at Scattered and Numerous densities with occasional Concentration density detected in the Central West district in mid-August, and frequent Scattered-density with occasional Numerous-density adults in the southern part of the Channel Country in late August. Occasional Isolated or Scattered-density adults were also identified in the Northeast and Flinders districts of South Australia, and the Upper Western district of New South Wales by surveys conducted in September. No captures were recorded by any light trap in White Cliffs or Dulkaninna. Although nil rainfall was received in much of inland eastern Australia in September in addition to below average to very much below average winter rainfall in the north-eastern part, with the forecast for above average rainfall for the remainder of spring and December, overwintering adult population should have favourable habitat conditions for survival and breeding. 

There is a moderate risk of a regional infestation in Central West Queensland. However, a widespread infestation is less likely to occur for the remainder of spring.

The overall population likely remained at a low level in Queensland. Survey had not identified any locust in the Central West and Channel Country of Qld since mid-August, and no locust reports had been received from previously infested areas. Nil rainfall was received in the north-eastern part of inland eastern Australia in September in addition to below average to very much below average winter rainfall. However, with the forecast for above average rainfall for the remainder of spring and December, habitat conditions should improve for locust survival and breeding with possible localised medium-density populations in sub-tropical Queensland.

There is a low-moderate risk of a regional infestation developing in the Central West and a low risk over much of inland eastern Australia in the reminder of spring.