Locust Bulletin October 2016

​​​ISSN 2204-9851

​​​​​​​​​​​​The Locust Bulletin is produced each month during the spring—autumn period and includes a general summary for each major locust species, details of known distributions with regional forecast an​d maps of locust distributions.​

General situation in September and outlook to December 2016

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Australian plague locust - Chortoicetes terminifera

Autumn locust distribution in most regions of New South Wales, Victoria, Queensland and South Australia was generally at low densities. However, localised high density nymphs and adults persisted in part of Southwest Queensland and the Far North region of South Australia during May. Breeding by that population produced a widespread low and medium density nymphal population in mid-August. Surveys identified nymphs at all development stages, indicating both direct developing and diapause eggs were produced in those regions during April and May. The widespread heavy rainfall during winter and early spring throughout all regions of eastern Australia has produced unseasonal vegetation growth in arid and summer rainfall areas. It has also produced dense ephemeral pasture growth in southern New South Wales, South Australia and Victoria. At this stage it is unclear if dense vegetation in southern regions will favour locust development, but it will provide opportunities for spring breeding in Queensland and northern regions of South Australia and New South Wales. Flooding and road closures have limited any APLC surveys and little information is available on current population level or development stages.

In New South Wales, autumn surveys identified low density adults in most regions. Medium density adults persisted in a small area south of Broken Hill, the Hillston–Booligal, Deniliquin and Balranald areas of the Riverina, and the Bourke–Louth area along the Darling River. Those areas are more likely to produce nymphs at medium and locally high densities during October and November.

Surveys were conducted in the Southwest and Northwest regions of Queensland in early August. Low density nymphs were detected at most stops in the Birdsville–Betoota–Bedourie area in Diamantina Shire and the Windorah–Arrabury area in Barcoo Shire. Occasional nymphs were also detected in Boulia Shire. Adult densities were low in surveyed areas. No information is available for the Central West, South Central and Central Highlands regions, but autumn egg laying was likely to have been at low densities.

In South Australia, only occasional adult locusts were detected around the Flinders Ranges in early September. Survey of the Far North in early August identified low density late instar nymphs at several locations in the Cordillo Downs and Clifton Hills areas. Band density hatching nymphs were recorded at one location. There were reports of locusts on the Eyre Peninsula and in the Murray Valley region in April. Nymphs are likely to develop at low densities in these regions and in parts of the Northeast and Far North during October, possibly with localised high densities and some bands.

There were several reports of adult locusts in parts of North Central and Northwest Victoria during April.  Low density nymphs are likely to develop in some areas during October. Some small patches of higher density nymphs could develop in late October, but are unlikely to produce large increases in adult population level in December.

The outlook for the remainder of spring is for localised low and medium density nymphs in all regions of New South Wales, parts of the Far North, Western Agricultural and Northeast regions of South Australia, and in Northwest and North Central Victoria. In Southwest Queensland and the Far North region of South Australia, adult numbers are likely to increase to medium densities, following fledging of early spring nymphs. Those adults could breed in October and produce a late spring nymph generation, resulting in a significant adult population increase in November or December. There is a low risk of widespread high density infestations in any region during spring 2016.

5 October 2016

Spur-throated locust - Austracris guttulosa

Adult population levels increased markedly in Northwest, Southwest, Central West and Queensland Gulf regions during late autumn. Young adults of this species live through winter in a non-reproductive state, often forming swarms that occupy woodlands and riparian tree lines. Breeding does not usually commence until the onset of the wet season. The unusual winter and September rainfall in Queensland have maintained grasses in green condition throughout the inland regions. There were several reports of swarms from the Winton–Cloncurry area in Northwest Queensland during August. Subsequent APLC surveys in early September identified medium and some swarm density adults throughout Richmond, McKinlay and Cloncurry Shires. Most samples of females showed no egg development, but a proportion of females from a swarm near Julia Creek contained 4-5 mm eggs. Egg development has not previously been recorded in September. It is possible that early sexual maturation could result from unseasonal favourable grassland habitat conditions. Egg development was recorded in October after heavy rainfall in New South Wales in 1975, but did not occur until November in Queensland. The outlook for further spring rainfall in these regions presents the possibility of breeding commencing earlier this season than in recent years. The outcome for overall population increase during 2016–2017 is unclear at this stage, but an extended breeding period and multiple egg layings are likely if the wet season commences early.

Surveys in early September identified consistent Scattered density adults in the Longreach district and Winton Shire, Scattered–Numerous adults in Boulia Shire and Isolated density adults in Barcoo and Diamantina Shires. The Longreach light trap recorded low numbers of locusts on many nights during August, but only on two nights during September.

Favourable habitat conditions for breeding have been maintained by heavy rains during winter in the Southwest and Northwest regions of Queensland. Sporadic egg laying could commence in October and first nymphs could appear in November. Egg development to hatching in this species takes 3–4 weeks and nymph development a further 8–10 weeks. Females can lay multiple times during summer. Nymphs of this species usually do not aggregate to form bands, but can reach densities of 30 m2 in favourable habitats.

The outlook is for an overall increase in population during 2016–17 as a result of an early commencement of breeding. There is a moderate risk of swarms persisting in the Central West, Northwest and Central Highlands regions of Queensland until December.

Migratory locust - Locusta migratoria

No information is available on the current distribution of this species. Low density adults and occasional nymphs were identified in parts of the Central Highlands and South Central regions of Queensland in late March. These regions, along with eastern parts of Central West Queensland are where populations are regularly found and where rapid population increases usually occur. They have received above average winter and September rainfall, which has produced favourable habitat conditions for continued low density breeding.

There is a low probability of widespread gregarious populations developing in the Central Highlands, eastern Central West or South Central regions of Queensland during spring. However, gregarisation can occur at local scales and is often associated with cropping. Small gregarious populations could develop in localised areas of the Central Highlands.

It is important that any locust activity be reported as soon as possible to your local biosecurity authority, primary industries department or to the commission. A toll–free call to the APLC can be made on 1800 635 962. An answering machine is attached for after–hours calls. Reports can also be e–mailed to APLC or made through the internet at Australian Plague Locust Commission.

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Australian plague locust distribution 1 August to 30 September 2016

Map of Australian plague locust distribution 1 August to 30 September 2016 

Situation in September and forecast to December 2016

New South Wales

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Central West and Northwest Plains
Central West, Northwest and Central Tablelands Local Land Services

Locusts and conditions

  • The locust population remained at generally low densities and there were no reports.
  • Continuous wet conditions and road closures prevented any APLC surveys. There is likely to have been some low–medium density egg laying in autumn. The majority of any eggs will have entered diapause and commenced hatching during September.
  • Previous surveys in Central West Local Land Services (LLS) area in April identified Isolated–Scattered density adults in the Nyngan–Tottenham–Carinda area, and Scattered–Numerous density adults were recorded in the Condobolin–Euabalong–Tullibigeal area.
  • These regions have received rainfall amounts well above average during each of the last four months. September totals exceeded 100 mm over much of the Central West, Northwest and Central Tablelands LLS areas. Pasture vegetation is green and dense.

Forecast

  • Low–medium density nymphs are likely to develop during October, with localised high densities possible in parts of the Central West LLS area. Dense, wet ground vegetation may increase nymph mortality in some areas. Fledging of surviving nymphs will occur during November, resulting in a moderate increase in adult numbers, but swarm formation is unlikely in any area.
  • There is a low probability of significant immigration from other regions during October or November.

Risks

  • There is a low risk of widespread infestations developing during spring.

Riverina
Riverina and Murray Local Land Services

Locusts and conditions

  • Locust population level is likely to have remained low during September. No APLC surveys were conducted and there have been no reports.
  • Previous surveys in April identified Scattered–Numerous density adults in the Hillston and Deniliquin districts, and Isolated–Scattered densities in other areas. Autumn egg laying is therefore likely to have been at low–medium densities, with higher densities possible in localised areas.
  • There is likely to have been some egg laying in late March and April. The majority of eggs will have entered diapause.
  • The region received moderate rainfall (20–40 mm) each month during winter and heavy rainfall, with totals exceeding 100 mm during September. Pasture vegetation is green.

Forecast

  • Hatching will commence in late September in northern districts and mid-October in the south. Dense, wet pasture vegetation could reduce nymph survival in some areas if heavy rains continue during October.
  • Nymphs are likely to develop at low–medium densities, with localised high densities possible in some areas, including the Hillston and Deniliquin districts. Fledging of surviving nymphs will occur from mid-November, but a large adult population increase and swarms are unlikely to result.
  • There is a low probability of significant immigration from other regions during spring.

Risks

  • There is a low risk of a widespread regional infestation developing during spring.

Far West and Far Southwest
Western Local Land Services

Locusts and conditions

  • Adult locusts were at generally low densities during September. There were no reports.
  • Wet conditions and road closures limited APLC survey during September. The Broken–Menindee–Wentworth area was surveyed in early September. Scattered density adults were identified in the Broken Hill area and there were only occasional adults in other areas. No nymphs were detected
  • Previous surveys in April detected Scattered–Numerous density adults in the Bourke–Louth and Broken Hill areas, and Isolated–Scattered density adults in the Menindee–Pooncarie–Ivanhoe area.
  • The Fowlers Gap and White Cliffs light traps recorded no locusts in August or September.
  • Most areas in these regions received moderate rainfall (20–40 mm) each month during winter and heavy rainfall in September, with totals exceeding 100 mm. Pasture vegetation is green.

Forecast

  • There will have been sporadic autumn breeding in the Far West and Far Southwest regions. Low density nymphs are likely to develop in several areas during October. Medium density nymphs and possibly small Bands could occur in localised areas, including Bourke–Louth, Broken Hill–Menindee, Wilcannia-White Cliffs and Ivanhoe–Pooncarie.
  • Fledging of nymphs will commence in early November in the Far West region and mid-November in the Far Southwest. Adult numbers will increase to medium densities, but swarm formation is unlikely.

Risks

  • There is a low risk of a widespread regional infestations developing during spring.

All locust activity should be reported to your Local Land Services or the Department of Primary Industries, NSW. A toll-free call to the APLC can be made on 1800 635 962. An answering machine is attached for after-hours calls. Reports can also be e–mailed to APLC or sent through the web page at Australian Plague Locust Commission.

Queensland

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Southwest
Barcoo, Bulloo, Quilpie and Diamantina Shire

Locusts and conditions

  • The late autumn population in Diamantina and Barcoo Shires produced a widespread low density nymph population in August. The continued rainfall in the region during winter and in September maintained green vegetation.
  • Surveys in early August identified Present density nymphs at many locations in Diamantina and western Barcoo Shires. All nymph development stages were recorded, with late instars most commonly encountered. These resulted from direct developing eggs laid in late May. Younger instars are likely to be from diapause eggs laid in April. Scattered–Numerous density young adults were associated with nymphs in Barcoo Shire. Isolated density adults were identified in Diamantina Shire.
  • Fledging of nymphs will have continued throughout August, producing a moderate increase in adult densities. However, maximum temperatures were well below average during September and will have restricted swarm formation, migration and breeding.
  • Heavy rainfall and flooding prevented any survey during September.
  • The Birdsville and Nooyeah Downs light traps recorded no locusts during August or September.
  • Most of the region received moderate–heavy rainfall (20–>40 mm) each month during winter and heavy rainfall in September, with totals exceeding 100 mm in some areas.

Forecast

  • Favourable habitat conditions throughout the region will provide opportunities for breeding during October. Egg laying may have commenced in September. There is a moderate probability of a widespread spring nymph generation developing during October and habitat conditions will remain favourable for nymph survival. Nymphs are likely in to occur at medium densities and some localised Bands could be detected. Given the widespread green vegetation and ample soil moisture, breeding is unlikely to be synchronised. A range of nymph development stages and fledging times is possible during October. Localised increases in adult density are possible during November, but the likelihood of swarm formation is unknown at this stage.
  • There is a moderate probability of migrations from and redistribution within the region during November and December.

Risks

  • There is a moderate risk of widespread locust breeding during spring.

Central West & Northwest
Longreach, Barcaldine and Blackall-Tambo Regional Council. Boulia, Cloncurry, Flinders, Mckinlay, Mt Isa, Richmond and Winton Shire

Locusts and conditions

  • The locust population level was generally low in surveyed areas during August and September.
  • Parts of Longreach Regional Council (RC) area, and of Boulia and Winton Shires were surveyed in early August. Only occasional adults were recorded in the Longreach area and Isolated–Scattered density adults in Boulia and Winton Shires. Occasional late instar nymphs were recorded in Boulia Shire.
  • Surveys in early September identified only occasional adults in McKinlay, Cloncurry and northern Boulia Shires.
  • Heavy rainfall and road closures prevented any survey of the Central West during September.
  • The Longreach light trap recorded no locusts during August or September.
  • Most areas of the Central West and parts of the Northwest region received moderate–heavy rainfall (20–>40 mm) each month during winter and heavy rainfall in September, with totals exceeding 100 mm in some areas. Pasture vegetation is green.

Forecast

  • Population level is expected to remain generally low in these regions during spring, however habitat conditions remain favourable for breeding and nymph survival. If there was more than sporadic, low density egg laying in the Central West in late autumn there could be localised medium or high density nymphs in some areas, which would fledge during October. There is likely to be a moderate increase in adult numbers in October or November. Given the low population level recorded in autumn, the probability of swarm formation remains low.
  • Nymphs in Boulia Shire will have fledged by September and may commenced breeding in October. This could produce nymphs or fledgling adults in November, but a large increase in adult densities is unlikely.
  • There is a moderate probability of low density immigration or redistribution during spring.

Risks

  • There is a low risk of a widespread regional infestations developing during spring.

Central Highlands
Central Highlands and Isaac Regional Council

Locusts and conditions

  • Locust densities are expected to have remained generally low during August and September. No surveys were conducted and there were no reports of locust activity.
  • Previous surveys in autumn identified Isolated–Scattered density adults.
  • The region received above average winter and September rainfall.

Forecast

  • Habitat conditions are suitable for locust breeding and nymph survival. Nymphs from any autumn breeding will fledge during October, but a large increase in adult population level is unlikely. Localised higher density populations could develop in some areas in southern Central Highlands Regional Council (RC) area.
  • There is a low probability of immigration from other regions during spring.

Risks

  • There is a low risk of a widespread infestation developing during spring.

South Central & Darling Downs
Balonne, Murweh and Paroo Shire. Maranoa, Western Downs and Goondiwindi Regional Council

Locusts and conditions

  • Locust population levels are expected to have remained generally low during August and September.
  • No surveys were conducted and there were no reports of locust activity.
  • Previous surveys in autumn identified only low density adults and occasional nymphs.
  • Much of the region received heavy rainfall (>40 mm) in June, August and September. Pasture vegetation is green in most areas.

Forecast

  • Given the low population level detected in previous autumn surveys, high density nymphs are unlikely to develop during spring. However, some sporadic autumn egg laying was likely and habitat conditions are favourable for nymph survival. An small increase in adult numbers is likely in November.
  • There is a low probability of significant immigration from other regions during spring.

Risks

  • There is a low risk of a widespread regional infestation developing during spring.

Locust activity should be reported to Biosecurity Queensland (Queensland Department of Agriculture and Fisheries) on 132 523. A toll free call to the APLC can be made on 1800 635 962. An answering machine is attached for after-hours calls. Reports can also be e–mailed to APLC or sent through the web page at Australian Plague Locust Commission.

South Australia

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Far North, Northeast, Northwest & Western Agricultural Region

Locusts and conditions

  • Late autumn breeding in the Far North region produced a localised nymph generation in August. Autumn reports indicate sporadic low density breeding in several other regions.
  • The adult population identified in May laid eggs in favourable habitat and nymphs were identified in early August. Present and Numerous density late-instar nymphs were identified in several locations in the Cordillo Downs–Cadelga and Clifton Hills–Birdsville areas. Band density first instar nymphs were detected at one location. Older nymphs are from direct developing eggs laid in late May, while early instars are likely to be from diapause eggs laid in April. Only Isolated density adults were identified in these areas. Fledging of nymphs will have been completed during September.
  • Limited survey on either side of the Flinders Ranges in the Northeast and Far North regions in early September identified Isolated–Scattered density adults in the eastern areas, while none were recorded on the western side. No nymphs were detected. Heavy rainfall and road closures prevented any further survey during September.
  • There was an unconfirmed reports of nymphs near Melrose in the Northeast region in mid-September. At this stage it is unclear if these were locusts or the grasshopper Austroicetes cruciata.
  • Numerous density locusts were reported at Karkoo on the lower Eyre Peninsula and near Ceduna in April. Sporadic medium density egg laying will have occurred in the Western Agricultural region.
  • The Dulkaninna light trap did not record any locusts in August or September.
  • Most areas in these regions received moderate–heavy rainfall (20–>40 mm) during June, August and September. Pasture vegetation is green.

Forecast

  • Localised, low and medium density nymphs are likely to develop in parts of the Western Agricultural, Murray Valley and Northeast regions during October. There is a low probability of Bands developing except in a few restricted instances. Fledging will occur during November and a moderate increase in adult numbers is likely.
  • Further localised breeding is possible in parts of the Far North during October. If this occurs, a further generation of nymphs would develop during October as habitat conditions will remain favourable for nymph survival. Nymphs are likely in to occur at low–medium densities, but localised small Bands are possible. Given the widespread green vegetation and ample soil moisture, breeding is unlikely to be synchronised and a range of nymph development stages and fledging times are likely.
  • There is a low probability of significant migrations into these regions during spring.

Risks

  • There is a low risk of widespread regional infestations developing in spring.

Murray Valley, Mt Lofty Ranges & Southeast Region

Locusts and conditions

  • Locust densities are expected to have remained low. No surveys were conducted and there have been no reports.
  • A report of locusts from the Karoonda area in the Murray Mallee district in late April suggests some sporadic autumn egg laying occurred.
  • Most areas received moderate–heavy (20->40 mm) during each of the last four months, with many areas receiving totals exceeding 100 mm in September.

Forecast

  • Low density nymphs could develop in a few locations during October.
  • There is low probability of any significant immigration during spring.

Risks

  • There is a low risk of a widespread infestation developing during spring.

Locust activity should be reported to Biosecurity SA (Primary Industries and Region South Australia) on the Locust Reporting Hotline on 1300 666 101. A toll-free call to the APLC can be made on 1800 635 962. An answering machine is attached for after-hours calls. Reports can also be e–mailed to APLC or sent through the web page at Australian Plague Locust Commission.

Victoria

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North West & North Central Victoria

Locusts and conditions

  • There were several reports of low and medium density locusts in the North Central and Northwest regions, and as far south as the Wimmera district in autumn. There have been no reports since autumn.
  • APLC surveys in the Northern Mallee district in mid-April identified Isolated–Scattered density adults in the Ouyen–Swan Hill area.
  • These regions received heavy rainfall during September, with totals >100 mm in most areas. Pasture vegetation is green.

Forecast

  • Hatchings will commence in early October in the Northwest region and mid-October in North Central Victoria and the Wimmera. Low and medium density nymphs are likely to develop in localised areas, but any high densities or small Bands will be restricted to small areas in the North Central region.
  • Dense, wet ground vegetation may increase nymph mortality in some areas. Fledging of surviving nymphs will occur after mid-November, but a large adult population increase is unlikely.
  • There is a low probability of any significant immigration during spring.

Risks

  • There is a low risk of a widespread infestation developing during spring.

Locust activity should be reported to Department of Economic Development, Jobs, Transport and Resources on 1300 135559. A toll-free call to the APLC can be made on 1800 635 962. An answering machine is attached for after-hours calls. Reports can also be e–mailed to APLC or sent through the web page at Australian Plague Locust Commission.

Glossary of locust terms and density categories used in the Locust Bulletin

Locust biology and behaviour

TermDefinition
adultA fully winged, mature locust capable of breeding and migrating
bandDense aggregation of nymphs, usually moving forward together
diapausePeriod of dormancy in anticipation of unfavourable environmental conditions
egg bedAn area of soil containing many egg pods (up to 1000 per square metre)
fledgeFinal nymphal moult to a soft-bodied adult incapable of long-distance flight
instarDiscrete stages of nymphal development each separated by a moult
layingFemale locusts each depositing clutches of 20-60 eggs into the ground in froth-lined egg pods
nymphJuvenile wingless locust. Often referred to as the hopper stage
swarmDense aggregation of adults, milling at the same spot or flying closely together

Locust density categories

Where higher densities occur, a large proportion of the regional population is concentrated in very small areas with lower densities elsewhere, so the higher densities cannot be extrapolated over the area of an entire region. A range of density classes is usually found within a surveyed region.

Nymph DensitiesNumber per m2
Present1 – 5
Numerous6 – 30
Sub–band31 – 80
Band> 80

Adult DensitiesNumber per m2Number per hectare
Isolated– 0.02< 200
Scattered0.03 – 0.1> 200 – 1000
Numerous0.2 – 0.5> 1000 – 5000
Concentration0.6 – 3.0> 5000 – 30,000
Low Density Swarm4.0 – 10> 30,000 – 100,000
Medium Density Swarm11 – 50> 100,000 – 500,000
High Density Swarm> 50> 500,000

General density classesNymph densitiesAdult densities
very low, occasionalNil–PresentNil–Isolated
lowPresentIsolated–Scattered
mediumNumerous—Sub–bandScattered–Numerous
highBandsConcentration–Swarms

Reporting locust infestations

It is important that all locust activity is reported as soon as possible to your nearest state agriculture agency office or to the Australian Plague Locust Commission.

StateAuthority for reporting locusts
New South WalesLocal Land Services (LLS) or Department of Primary Industries
QueenslandBiosecurity Queensland, Department of Agriculture and Fisheries
South AustraliaBiosecurity SA, Primary Industries & Regions South Australia (PIRSA)
VictoriaBiosecurity Agriculture, Department of Economic Development, Jobs, Transport and Resources

Reports to the Australian Plague Locust Commission can be made by:

Free call (Canberra): 1800 635 962 (24 hours)
Fax (Canberra): (02) 6272 5074
​ E–mail: APLC
Internet: Australian Plague Locust Commission

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