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Current Locust Situation and News
Locust situation in October 2008
This page summarises the known distribution of locusts during September and provides a brief outlook to November 2008. The next Locust Bulletin will be published in early November 2008.
- Australian Plague Locust Situation
- Map of areas of possible band development
- Forecast development dates
- Spur-throated Locust Situation
- Migratory Locust Situation
Australian Plague Locust (Chortoicetes terminifera)
Spring hatching began during the last week of September in the eastern Riverina and southern Central West of New South Wales. Over forty reports of nymphs emerging at high densities in Narrandera, Forbes, Wagga, Condobolin, Gundagai, Young and Murray Rural Lands Protection Board (RLPB) areas were confirmed by RLPB staff by the end of the month. Hatchings were at band density in numerous locations, but at this stage only small bands of first instar nymphs have formed, mostly less than 200 m long. Further hatchings are expected in Hume, Riverina and southern Murray RLPB areas, and across northern Victoria during the first week of October. Warm weather during September caused eggs to complete development rapidly and peak hatching has occurred up to a week earlier than expected.
A widespread nymphal infestation with many small bands will develop in the Riverina and Central West of New South Wales, and in North Central Victoria during October and November. The overall scale of likely control operations is difficult to predict, but experience from recent spring outbreaks in these regions indicates a potential for more than 25,000 ha of control.
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. Control of extensive areas of high density bands will be coordinated if required by RLPBs, NSW and Victorian Departments of Primary Industries and the APLC, with cooperation across jurisdictions.
A map of the area within which high density spring hatchings are likely and a table of forecast dates for development stages are given below. High density hatchings are occurring in Murray, Wagga, Narrandera, Condobolin and Forbes RLPB districts, extending into the western edge of Gundagai and Young RLPB districts. Egg laying also occurred in southern areas of Dubbo and Molong, and in Riverina and Hume RLPB areas, where hatchings will begin in early October. RLPB staff plan to begin control in early October and have commenced distribution of pesticide to landholders. Nymphs in the Riverina and Central West will reach mid-instar stage from 10 October and fledging will begin in early November. Adult population density will increase to high densities and there is the potential for swarms to form during November.
In Victoria spring hatchings will begin from early October in the area bounded by Wodonga, Wangaratta, Rushworth and Echuca. High density nymphs are likely to develop in some locations during October and November and control is anticipated by DPI Victoria and landholders.
Population density is low in the NSW Northwest Plains, Far West and Far South West regions. Surveys in Queensland also indicated a very low population density in most regions during September.
September surveys in northern South Australia identified a very low density adult population in the Far North and around the southern Flinders Ranges.
Map of areas of possible band development during spring
Based on known distribution of adults in autumn, egg beds and reports.
Forecast hatching and development dates for indicative locations in NSW and Victoria
Peak hatching represents emergence of majority of the nymphal population. Dates are estimated from the recorded temperatures at these locations to 30 September. Mid-instar dates provide an indication of appropriate control timing. Fledging dates indicate the development of winged adults.
| Location - NSW | Peak hatch | Mid-instar | Fledging |
|---|---|---|---|
| Dubbo | 23 September | 8 October | 28 October |
| Condobolin-Hillston | 19 September | 3 October | 25 October |
| Molong-Forbes | 26 September | 11 October | 1 November |
| Wyalong-Temora | 25 September | 10 October | 1 November |
| Narrandera-Lockhart | 29 September | 11 October | 5 November |
| Deniliquin-Walbundrie | 28 September | 13 October | 8 November |
| Wagga-Wagga | 10 October | 25 October | 15 November |
| White Cliffs-Wilcannia | 5 September | 20 September | 11 October |
| Menindee-Ivanhoe | 10 September | 24 September | 15 October |
| Hay-Booligal | 18 September | 3 October | 25 October |
| Nyngan-Coonamble | 31 August | 18 September | 10 October |
| Walgett-Brewarrina | 23 August | 10 September | 2 October |
| Moree-Goondiwindi | 27 August | 13 September | 6 October |
|
Location - Victoria |
Peak hatch | Mid-instar | Fledging |
| Echuca-Wangaratta | 4 October | 19 October | 9 November |
| Swan Hill-Mildura | 26 September | 11 October | 2 November |
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 2008. Surveys in April indicated a redistribution of the immature adult population, with densities declining in the Central West and increases to Scattered–Numerous density in Southwest and South Central Queensland. High density adults were reported from southwest of Springsure in Bauhinia Shire during April. Surveys in April in New South Wales indicated a population increase with widespread Isolated–Scattered density counts in the Far West and Northwest Plains.
Immature adults often redistribute during autumn and form overwintering swarms, which feed in green vegetation and roost in trees. There were several reports of swarms from the northern part of Central West Queensland during June, July and August. Swarms were also reported from near Normanton in the Queensland Gulf during winter. Surveys by Biosecurity Queensland identified several swarms northeast of Aramac in mid-August.
Surveys during September indicate a widespread low density population throughout most of Queensland and northern NSW, representing a consistent background population. No egg development was found in samples during September.
Adults migrate and disperse to commence breeding from the start of the northern wet season. An increase in detected numbers may result from the dispersal of swarms and the onset of breeding in October–November.
Migratory Locust (Locusta migratoria)
There was a persistent population in the Emerald–Springsure area of Queensland, with at least three generations of nymphs identified during 2007-08. In early March small Bands of mid-instar nymphs were identified by Biosecurity Queensland staff in sorghum crops on properties in that area, and a consistent low density adult population during April. In mid-April Biosecurity Queensland carried out control of swarms southeast of Capella.
Surveys during September identified low density adults between Brewarrina and Goodooga on the NSW Northwest Plains, and in the St George area in southern Queensland. Female samples showed 2-3 mm egg development. Vegetation conditions in northern NSW and southern Queensland are suitable to support breeding, following heavy rains in early September, which could produce a nymphal generation in some areas during October.
2 October 2008