The locust population level remained generally low in much of inland easternAustralia, but parts of the Central West, Far West and Far Southwest regionsof New South Wales currently have areas of moderate to high nymph and adultpresence. Surveys in October 2020 identified consistent low numbers of adultsand occasional nymphs in parts of the Northwest, Southwest and Central Westregions of Queensland, and in the Far North and Northeast regions of SouthAustralia. In New South Wales high density nymphs and adults were detected inthe Nyngan-Cobar areas where dense hatchings were previously observed orreported.
October rainfall was above average across much of south-eastern Australia.Large parts of the Far North and Northeast of South Australia and southwestNew South Wales received very much above average rainfall. Rainfall was alsoabove average in areas of north-western Victoria and eastern New South Wales,but about or slightly below average across large parts of Queensland andcentral New South Wales. Temperatures were above average, especially ineastern Queensland and New South Wales. As La Niña event is likely to continueat least into February 2021, above average rainfall is expected in much ofeastern Australia and there is a high probability of locust breeding withinfavourable habitats.

Surveys in Queensland in mid-October identified only a few nymphs in theBoulia area with consistent low numbers of adults between Longreach andUrandangi. As there were only light to moderate rains in late October apartfrom some localised storms during the month, localised breeding could possiblyproduce some bands and swarms within widespread low to medium densitypopulations.

In New South Wales, surveys in October were conducted with the focus onmonitoring potential population upsurges in the Central West, while new locustreports were noted within the region and adjacent areas. Surveys detectedwidespread low numbers of nymphs and adults in the Warren-Brewarrina-Mungindi-Moree-Coonamble areas, frequent medium numbers in the Nyngan-Wilcannia-Ivanhoe-Hillston areas with some bands and swarms detected, while low numbersof adults were observed in the Broken Hill-Tibooburra areas. With favourablehabitat conditions expected to remain, a high rate of locust breeding islikely to produce more bands. Under suitable weather systems, redistributionsand aggregations are possible and thus swarms are likely to appear in manyareas from now into December.
Limited surveys were conducted in late October in South Australia. Frequentlow numbers of adults were observed in the Yunta-Peterborough-Hawker areas,low to medium density nymphs near Wilmington, and occasional adults betweenLyndhurst and Innamincka with medium density nymphs near Innamincka. Withsuitable habitats resulting from September and October rainfalls, localisedlow to medium-density populations might occur in these areas in subsequentgenerations.
No surveys were carried out in Victoria and no locust reports were received.Overall local population density is expected to remain low.

The outlook for the remainder of 2020 is for an increase in overall populationlevel, with widespread medium to high densities possible in New South Walesbut limited to localised in other States. It is likely that more swarmformation will occur late in the spring generation and nymphal bands wouldresult in the summer generation from their successful breeding.

There is a moderate likelihood of more widespread high-density populations andregion-wide infestations developing during late spring and summer.

Spur-throated locust – Austracris guttulosa

Surveys in October identified consistent low numbers of adults betweenLongreach and Urandangi in Queensland, with very few adults in New South Walesand South Australia. The light trap at Fowlers Gap caught one adult on the15th October.

The widespread September rainfall produced some vegetation responses, but onlyaverage October rainfall occurred in much of central Queensland which isunlikely to have resulted in early breeding. Nonetheless the patchy Octoberrainfall may have induced population aggregation, while forecast above averagerainfall in coming months should generally improve habitat conditions.Consequently, widespread low to medium densities of nymphs are likely toappear from sporadic breeding in much of Queensland with some localised high-density populations most likely to occur in the Central Highland region, butonly limited breeding likely in New South Wales and South Australia given thevery low background population.

There is a low risk of a widespread infestation but possible region-wideinfestation in subtropical Queensland developing during late spring andsummer.

Migratory locust – Locusta migratoria

Surveys in October did not detect any migratory locust, but under improvedvegetation conditions from September and October rains, localised breeding islikely in the Central Highlands of Queensland to produce some low to mediumdensity populations. High-density gregarisation is unlikely to develop fromthe current very low background level.

There is a very low risk of a widespread infestation developing during latespring and summer.

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