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Current Locust Situation and News
Locust situation in May 2008
This page summarises the known distribution of locusts during autumn 2008 and provides a brief outlook to spring 2008. The next Locust Bulletin will be published in spring 2008.
Australian Plague Locust (Chortoicetes terminifera)
The adult locust population increased to high densities in the eastern Riverina of New South Wales during March. This was primarily the result of the aggregation of locusts that fledged in this region in late February and early March, but some migration from the Central West in early March may have contributed to the increase. Concentration and swarm density adults with developed eggs were widespread in Murray, Wagga and the western part of Hume Rural Lands Protection Board (RLPB) districts, but numbers had declined to medium densities by the end of April. Egg laying began in the Riverina in late March and continued during April and into early May. A potentially serious nymphal infestation with many bands is therefore expected to develop in the Riverina in October and November.
Redistribution of adults during April produced a widespread medium density population in the southern Central West and Riverina of New South Wales, and in North Central Victoria at the start of May. Some egg laying has occurred in all these regions and more localised medium density hatchings, with bands developing in some locations, is likely in spring. Highest density spring hatchings are expected in Murray, Wagga, southern Narrandera, western Hume and Riverina RLPB districts, where hatchings will begin in early October with a peak in mid-October. Landholder identification and control of small bands on farmland will be critical to minimising the impact of locust nymphs on crops and pastures during October and November.
Locust density remained low in the Northwest Plains and northern part of the Central West of New South Wales during April, following the decline in early March. Medium to high density adults developed in southern Forbes and Condobolin, and in Molong RLPB districts, and extended into the western edge of Gundagai and Young RLPB districts. Spring hatchings from autumn egg laying will begin in late September in these areas. In the Far West and Far Southwest regions of New South Wales nymphs fledged in the Wanaaring–Tibooburra area and the Menindee–Ivanhoe area during March, which produced small areas of high density adults in the Wilcannia–White Cliffs and Sayers Lake–Darnick areas in early April. Egg laying may have occurred in the White-Cliffs area during April.
In Victoria, reports of adult locusts between Echuca and Wodonga in North Central Victoria began in late March. The population in Victoria is primarily the result of migration from adjacent areas of the Riverina in March and April, but low numbers of adults could have migrated into this region and bred at low densities from as early as January. There were further migrations of adult locusts into Victoria during April and surveys identified a widespread medium density population in the area bounded by Wodonga, Wangaratta, Rushworth and Echuca, with up to Concentration density adults in some locations. There were also reports west of Echuca, and as far south as Nhill in Northwest Victoria in late April. The presence of occasional nymphs indicates egg laying occurred in some locations in Victoria from late March and continued during April. Medium density nymphs and some small bands are likely to develop in November.
Locust densities in most regions of Queensland and northern South Australia declined to very low levels during April apart from some low density adults and occasional nymphs near Cunnamulla in Paroo Shire, South Central Queensland.
Spur-throated Locust (Austracris guttulosa)
There was a widespread medium density adult population throughout the Central Highlands and Central West Queensland, with up to Concentration density immature adults in several shires during March. Surveys in April indicate a redistribution of the immature adult population, with densities declining in the Central West and increases to Scattered–Numerous density in Southwest Queensland and in the Paroo Shire. There were Isolated–Scattered density adults in other parts of south Central Queensland and the Darling Downs. Fledging of this summer generation was completed by the end of March and no nymphs were found on survey. High density adults were reported from southwest of Springsure in Bauhinia Shire during April.
Longreach light trap recorded high numbers of locusts during 5–17 March, with a peak of over 800 on 8 March, and during 7–9 April. The light trap at Julia Creek recorded over 50 locusts on 13 and 14 March and low numbers in mid-April. The activity at Longreach may reflect redistribution and migration of the population of young adults in Central West Queensland. An increase in the numbers of adults in the Far West and the Northwest Plains of NSW was reported at the start of April. White Cliffs light trap caught low numbers on 31 March and in the first week of April, indicating redistribution and migration of the immature adult population. Surveys in April in New South Wales indicated a population increase with widespread Isolated–Scattered density counts in the Far west and Northwest Plains.
Some small swarms of adults may develop in the northern part of Central West Queensland, which is usual for this time of year. There was a report of swarms in the Richmond area in early May, and other swarms are likely to develop in the Queensland Gulf Country during winter. Immature adults often redistribute during autumn and form overwintering swarms, which may feed in green vegetation areas and roost in trees.
Migratory Locust (Locusta migratoria)
In early March small Bands of mid-instar nymphs were identified by Biosecurity Queensland staff in sorghum crops on properties in the area between Emerald and Springsure. Fledging occurred in late March. Surveys during April identified a consistent low density adult population in the area around Emerald and Springsure. In mid-April Biosecurity Queensland carried out 378 ha of control of swarms on a property southeast of Capella in Peak Downs Shire. While the risk of a significant infestation developing this locust season has declined, the seasonal outlook for above-average rainfall during autumn in part of eastern Queensland could allow further gregarious breeding in parts of the Central Highlands.
18 May 2008