This page summarises the known distribution of locusts during October 2014 and provides a brief outlook to January 2015.
The next Locust Bulletin will be produced in December 2014.
The locust population increased in several regions during October, after protracted hatching of nymphs during September and October. This resulted in widespread nymphs at various development stages and continuous fledging contributing to near synchronous adult population increases in many regions in late October. Most nymphs were recorded at medium densities and formed small bands in some locations, but these did not develop the density and sizes to enable aerial detection or justify APLC control in any region. Significant increases in adult population were recorded in Far West and Central West New South Wales and in South Central Queensland, where swarms formed in late October. Population increases were also recorded in Southwest and Central West Queensland, and in Far North South Australia, but little swarm formation has been recorded in these regions. Residual late instar nymphs were still present in all regions in late October and fledging will continue in early November. There is an increased risk of migrations into adjacent regions during November and early December.
The largest population in New South Wales is in the Far West region, where areas of medium and high density nymphs were recorded throughout the Broken Hill–Tibooburra and White Cliffs–Wilcannia areas in mid-October, along with fledgling adults at many locations. Swarms were reported in late October and further swarm activity is expected during November. In the Central West, a widespread nymph population developed in the Nyngan–Coolabah and Quambone–Carinda areas, with reports throughout October and swarm activity at the end of the month. Low density adults and nymphs were identified in the Far Southwest, Northwest Plains and Riverina, but moderate population increases are likely in these regions.
In South Central Queensland, a widespread medium density nymph population developed during October in Maranoa and Dalby Regional Council areas, and in Paroo Shire. Fledging in late October produced high density adults and some swarms in the Roma–Injune–Mitchell, Meandarra–Tara and Cunnamulla–Charleville areas. Fledging of medium density nymph populations in the Tambo–Augathella area in the Central West, and the Quilpie–Adavale and Noccundra–Kihee areas in Southwest Queensland also produced high density fledgling adults in late October. In the Central Highlands, a mixed population of locusts and other species, including Oedaleus australis, developed in the Emerald–Springsure area. Rainfall in the Central West and Central Highlands during September and October has produced suitable conditions for nymphal development and further possible locust breeding.
In South Australia, fledging of medium density nymphs produced a locally high density adult population in late October on the eastern side of the North Flinders Ranges and north of Olary near the New South Wales border.
Only occasional low density adults were identified in Northwest Victoria in late October and the risk of any widespread nymph population developing in November has declined.
The outlook for November–December is for an increase in adult population in most regions, with swarm formation to continue in Far West and Central West New South Wales and in South Central Queensland. Migrations to other regions are likely during November and December. The seasonal rainfall outlook for drier than average conditions indicates limited opportunities for widespread locust breeding, but the distribution of moderate–heavy rainfall in November and December will influence the likelihood and locations of a significant summer generation developing.
Surveys identified a consistent low density adult population in the Southwest, Central West, South Central and the Central Highlands regions of Queensland. Occasional Isolated density adults were identified in Far West, Far Southwest, Central West and the Northwest Plains of New South Wales. No nymphs were detected during October.
The current population of pre-reproductive adults are the offspring from breeding in the 2013-14 wet season. Adults usually commence breeding at the start of the northern wet season in November or December. However, heavy rainfall or green crops can initiate breeding as early as October. The heavy rainfall in the Central Highlands and eastern parts of the Central West Queensland in late September could have provided suitable conditions for some early low density breeding. Scattered storm rainfall in these regions and northern South Central Queensland during October is unlikely to initiate widespread egg laying and there have been no heavy tropical storms in the Queensland Gulf region. The seasonal rainfall outlook issued by the Bureau of Meteorology in October of a low probability of exceeding median rainfall in eastern Queensland supports an assessment of a low risk of a significant infestation developing during 2014-15.
Surveys during September and early October detected occasional adults in the Queensland Central Highlands. Although at low densities in the Central Highlands, rainfall in mid-August and during the second half of September and in October will have provided suitable conditions for localised breeding and a moderate population increase is possible during November or December. Gregarisation can occur at local scales, often associated with cropping in eastern Queensland, and can therefore be difficult to detect without intensive surveys. However, the risk of any widespread infestation developing before 2015 remains low.