Current Locust Situation and News
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Locust situation in September 2010
This page summarises the known distribution of locusts during August 2010 and provides a brief outlook to mid-October 2010. The next Locust Bulletin will be produced in September 2010.
Australian Plague Locust (Chortoicetes terminifera)
The outlook is for a serious widespread nymphal infestation of locusts in New South Wales, northern Victoria and eastern South Australia during spring as a result of egg laying by adult swarms during autumn. Some localised high density hatchings are also possible in Southwest Queensland. The plague situation, where numerous regions across several member states are affected by high densities of locusts, could continue during spring and summer if there is a high level of nymphal survival in spring.
The widespread heavy rainfall inland areas during last summer and autumn produced favourable habitat conditions, allowing three generations of population increase during 2009-2010. A large number of swarms formed in New South Wales, northern South Australia, and Southwest Queensland in early April 2010. Migrations to the south during April brought swarms into the Murray Valley and Northeast regions of South Australia, Northwest and North Central Victoria and the southern Riverina in New South Wales. Despite intensive control of nymphs of the third generation in New South Wales, eggs laid in autumn will produce a further generation of high density nymphs during spring.
Inter-agency meetings are continuing to plan and coordinate the response to the anticipated spring populations in New South Wales, Queensland, South Australia and Victoria. State agencies and industry groups are conducting landholder information meetings in areas likely to be affected. Information to assist landholders prepare for and implement locust control has been developed and is provided through APLC and state agency websites, industry group newsletters and discussions at landholder meetings.
High density hatching of eggs and the development of nymphal bands is expected during spring in the Central West, Far Southwest and Riverina regions of New South Wales, the Northwest and North Central regions of Victoria, and the Northeast and Murray Valley regions of South Australia. More localised high density hatchings are possible in Far West New South Wales, Southwest Queensland and the Far North and Southeast regions of South Australia. Subsequent formation of swarms could occur during November and December, following the fledging of nymphs.
In New South Wales spring hatching of eggs will commence in late August in northern areas, during September in the Central West, Lachlan and Western LHPA areas and from early October in the Riverina. Early hatching of nymphs was reported near Nyngan on 2 September. In South Australia hatchings will commence in mid-September in the Hawker area and from the end of September in the Murray Valley. Spring hatchings will commence in late September in Northwest Victoria, through to mid-October in areas south of Echuca and late October in the Horsham area.
The table of forecast development dates below is given as a guide to the expected emergence of nymphs in spring, but hatching will be distributed over a period of several weeks around those dates and timing will vary depending on local conditions and temperatures during late winter and early spring. Variations are likely as a result of the high proportion of non-diapause eggs laid during late autumn. Temperatures during July and August in southern states were below average. This, along with continued rainfall keeping soils moist, has resulted in low soil temperatures in many areas and the later peak hatching times in this table. However, egg samples from sites with sandy soils have shown embryo development of non-diapause eggs is more advanced than those in predominantly clay soils. This is the result of the higher thermal conductivity near the surface in sandy soils, where egg development continued during late autumn, and is likely to be significant in Northwest Victoria and the Mallee district in South Australia. Early hatching dates have been retained for these areas, where protracted hatchings are likely to occur from mid-September to mid-October.
2 September 2010
Map of locust risk zones for spring 2010
This map identifies key risk zones for anticipated locust control activity during spring 2010. The zones are based on observations and reports of high density autumn egg laying, swarm activity during autumn and habitats suitable for egg laying. Some localised high density spring hatching is also likely in areas outside these zones.
view larger sized image of the above map
| Location - NSW | Egg laying | Hatching | Mid-instar | Fledging |
|---|---|---|---|---|
| Brewarrina-Bourke | 24 April | 7 September | 22 September |
15 October |
| Tibooburra-Wanaaring | 24 April | 10 September | 25 September | 18 October |
| Broken Hill-Wilcannia | 25 April | 15 September | 30 September | 22 October |
| Ivanhoe-Hillston | 16 April | 25 September | 13 October | 2 November |
| Nyngan-Tottenham | 24 April | 15 September | 6 October | 26 October |
| Tullamore-Condobolin | 16 April | 5 October | 19 October | 7 November |
| Dubbo-Peak Hill | 16 April | 6 October | 20 October | 11 November |
| Parkes-Cowra | 16 April | 14 October | 28 October | 17 November |
| Forbes-West Wyalong | 16 April | 12 October | 26 October | 14 November |
| Hay-Balranald | 16 April | 5 October | 21 October | 4 November |
| Wagga-Cootamundra | 16 April | 25 October | 10 November | 26 November |
| Narrandera-Griffith | 16 April | 15 October | 29 October | 17 November |
| Jerilderie-Deniliquin | 16 April | 18 October | 31 October | 20 November |
|
Location - Victoria |
Egg laying | Hatching | Mid-instar | Fledging |
| Mildura-Ouyen | 16 April | 25 September | 14 October | 5 November |
| Swan Hill-Boort | 16 April | 6 October | 25 October | 14 November |
| Echuca-Bendigo | 16 April | 24 October | 6 November | 25 November |
| Shepparton-Tungamah | 16 April | 20 October | 3 November | 22 November |
| Nhill-Warracknabeal | 16 April | 17 October | 1 November | 20 November |
| Horsham-Stawell | 16 April | 24 October | 6 November | 1 December |
|
Location - SA |
Egg laying | Hatching | Mid-instar | Fledging |
| Marree-Lyndhurst | 16 April | 2 September |
17 September | 10 October |
| Andamooka-Roxby | 16 April | 5 September | 21 September | 15 October |
| Hawker-Orroroo | 16 April | 24 September | 10 October | 30 October |
| Port Augusta-Quorn | 16 April | 19 September | 4 October | 27 October |
| Renmark-Morgan | 16 April | 26 September | 12 October | 4 November |
| Pinnaroo-Karoonda | 23 April | 2 October | 21 October | 10 November |
| Keith-Bordertown | 23 April | 17 October | 1 November | 25 November |
| Kimba-Cowell | 5 April | 1 October | 18 October | 10 November |
|
Location - QLD |
Egg laying | Hatching | Mid-instar | Fledging |
| Thargomindah | 16 April | 24 August | 9 September | 3 October |
Peak hatchings dates are a guide only, as hatchings will extend for several weeks before and after the dates given. Forecast dates are based on development models for known or possible egg laying by adult populations and assume sufficient soil moisture for development after diapause. Dates are estimated using recorded temperatures to 30 August and long-term average temperatures. Dates indicate the majority of the population entering the life stage. Actual egg laying occurred over an extended period during autumn. Egg development rate is sensitive to temperature variation in late winter and early spring and early hatchings have occurred in recent years.
Spur-throated Locust (Austracris guttulosa)
Swarm formation continued in Central West, South Central and Southwest Queensland during July and August. The over-wintering adult population in these regions is significantly larger than has occurred in recent years. Surveys by Biosecurity Queensland in the Central West region identified numerous swarms in the Barcaldine-Blackall and Tambo-Charleville areas. Swarms were also identified in the Thargomindah–Cunnamulla area. Biosecurity Queensland officers have carried out aerial control of 109 swarms during June–August, covering a total of over 26,000 ha.
There have been numerous reports of swarm activity in the Hughenden, Winton, Richmond and Julia Creek areas of Northwest Queensland and in the Thargomindah-Cunnamulla area of Bulloo and Paroo Shires during July and August. The swarms are formed by immature adults which have developed from breeding during the 2009-2010 wet season. Similar densities of adults are likely to be in the Queensland Gulf region, other shires of Southwest and Northwest Queensland and in Murweh, Balonne and Paroo Shires in South Central Queensland. Only Isolated–Scattered density adults detected in the Central Highlands and the Roma Regional Council area. APLC survey during August identified low density adults in Murweh and Roma–Mitchell–St George areas.
In New South Wales Numerous–Concentration density adults were identified in the Brewarrina–Goodooga area of Northwest LHPA during April, but survey in early August detected mostly Scattered–Numerous density adults in this area. Similar densities are likely to be in the northern Bourke and Wanaaring districts of Darling LHPA.
An increase in adult numbers and formation of swarms in late autumn is usual for this species. Migratory activity of immature adults can result in regional population redistribution during autumn and again in late spring. Adults form largely sedentary swarms during winter, which may move into woodland areas. Breeding of adults usually commences in November and December in Queensland, but could occur earlier if heavy rainfall continues in western Queensland in September or October. The outlook is for a larger than average adult summer breeding population in parts of Southwest, Northwest and Central West Queensland. The population densities in the Central Highlands remained low during winter, but migration at the start of the wet season could result in an increase in swarm numbers in this region.
Migratory Locust (Locusta migratoria)
APLC surveys in during August identified occasional Isolated density adults of this species in the Cunnamulla and Roma areas in South Central Queensland and also in the Goodooga-Collarenebri area of the Northwest LHPA in New South Wales. Continued rainfall and green vegetation conditions in these regions has provided suitable conditions for breeding and continued low density populations are likely during September and October.
2 September 2010