Locust Bulletin February 2019

​​​​​​​​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 forecasts and maps of locust distributions.

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General situation in January and outlook to April 2019

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Australian plague locust - Chortoicetes terminifera

The locust population level remains low over most inland regions in eastern Australia. Only limited surveys were conducted during January, because of the very low numbers identified in previous months and continued very dry habitat conditions in inland areas.  Medium density young adults and nymphs were reported from several locations in the Hunter Valley and Central Tablelands regions of New South Wales during the second half of January. Population persistence in peripheral habitats when numbers are very low in the inland has also occurred during several previous widespread droughts. Several other species, notably the yellow-winged locust, have produced medium and locally high density populations in eastern districts of Queensland, New South Wales and Victoria.

Survey in the Riverina and Central West regions of New South Wales recorded only low density adult locusts in most areas. The localised population in the Lake Cargelligo district persisted during January, with medium density adults still in the same small area. Locust reports from the Hunter region extended from Muswellbrook to Murrurundi and from Bylong to Gulgong in the Central Tablelands.

No surveys were conducted in Queensland, but only occasional locusts were recorded in most areas in recent months. Heavy rainfall in the Northwest, Southwest, Central West and Gulf regions of Queensland at the end of January will produce widespread favourable habitat for locust breeding.

Previous surveys in South Australia recorded no locusts and habitat conditions remain very dry.

No surveys were conducted in Victoria, but locust numbers are expected to have remained low in inland habitats. The population persisting in the Omeo–Swifts Creek area in East Gippsland in January is mixed with several grasshopper species. Surveys by Agriculture Victoria indicate that locusts only make up a small proportion of the total numbers of flying insects.

The outlook for February and autumn is for population densities to remain generally low in inland eastern Australia, although small population increases are likely in New South Wales and Queensland. A moderate population increase is likely in eastern New South Wales, particularly in the Central Tablelands, Northwest Plains, and Central West regions. Further breeding is possible during February in the Central Tablelands and Hunter Valley and small swarms could develop in autumn. Low density migrations from these areas could increase adult population levels in the Central West and Northwest Plains regions.  Heavy rainfall in Northwest, Central West and parts of Southwest Queensland will provide favourable habitat for widespread locust breeding. Nymphs are likely to develop in some areas from late February, but mostly at low densities. An increase in adult numbers to medium densities is likely in parts of these regions during autumn. The Bureau of Meteorology seasonal outlook for February to April 2019 indicates continued above average temperatures, which could increase locust mortality in dry regions. The rainfall outlook predicts average rainfall is likely in New South Wales and Queensland. Despite the low current population levels, successful breeding could therefore result in population increases in some regions during autumn. However, there is currently a low probability of high density populations developing in any inland region.

There is a low probability of widespread regional infestations developing during February or autumn.

5 February 2019

Spur-throated locust - Austracris guttulosa

The population level remained very low in areas surveyed during December and January. No surveys were conducted in Queensland during January and the species was not detected in New South Wales.

The heavy rainfall in the Northwest, Central West and Gulf regions of Queensland at the end of January will provide the first opportunity for widespread breeding for 2018-19. Adult females can produce several pods and egg laying is often initiated after rainfall. However, the very low adult population numbers in surveyed regions are unlikely to produce a large nymph population. Hatching is likely during March and nymphs would fledge in late April. Nymphs and eggs are susceptible to desiccation and high nymph mortality can occur if habitat conditions become dry.

There is a low risk of a widespread infestation developing during 2018-19.

Migratory locust - Locusta migratoria

No surveys were conducted in Queensland during January. This species has not been detected since October, when very low numbers were recorded in the southern Central Highlands region of Queensland. Rainfall in that region and parts of Central West and Northwest Queensland during January could initiate low density breeding that would contribute to maintaining an overall low population density.

There is a low risk of a widespread infestation developing during February or autumn.

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.

Locust distribution map – Chortoicetes terminifera

Map of Australian plague locust distribution 1 January to 31 January 2019

Australian plague locust (Chortoicetes terminifera)

Situation in January and forecast to April 2019

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 low densities across most areas of the Central West and Northwest Local Land Services (LLS) regions, but localised medium–high densities have developed in the northern Central Tablelands and western Hunter LLS areas.
  • LLS staff reported both adults and nymphs from several locations in the upper Hunter Valley from Muswellbrook north to Murrurundi during the second half of January. Locusts were also reported south of Tamworth in Northwest LLS. There were reports from several locations in the Gulgong–Bylong area in northern Central Tablelands LLS. Young adults became more visible after mid-January, with flying concentrations of mixed species reported in several locations. Various nymph stages, mostly at low densities, were recorded in some areas and are likely to represent a second generation in this region. Several other species, including Gastrimargus musicus, are involved in many areas.
  • Surveys in mid-January identified Isolated density adults in the Condobolin–Tullamore–Peak Hill–Narromine area. Scattered density adults were recorded at the persistent local population near Euabalong, north of Lake Cargelligo, and residual late instar nymphs were still present.
  • There was light-moderate rainfall (<20-40 mm) in southern half of the Central West LLS during 8–14 January. There was localised moderate rainfall (20-40 mm) in the eastern Central West and Northwest LLS areas and in Central Tablelands LLS during 17–23 January.

Forecast

  • Despite high temperatures and drying habitats during January, storm rainfall maintained green vegetation in localised areas, particularly in the eastern half of these regions. This will provide opportunities for further sporadic breeding in those districts with high numbers of adults in the Central Tablelands and Hunter LLS areas, and low density breeding in elsewhere in the Central West and Northwest LLS areas. Egg laying occurred in December and January, and the current nymphs in the Central Tablelands and Hunter LLS will continue to fledge during February. Egg laying by the current cohort of adults is likely during February, with nymphs appearing from late February. Nymphs could develop at high densities in limited areas, but Present–Numerous densities could be more widespread.
  • There is a moderate probability of low density migrations from the Central Tablelands into the Coonabarabran and Dubbo–Coonamble districts, or from the northern Hunter LLS into the Gunnedah–Narrabri district during February. This could contribute to adult population increases to Scattered–Numerous density in some locations. Subsequent successful breeding in these areas will depend on the distribution of rainfall in February and March. 

Risks

  • There is a low risk of a widespread regional infestation developing during February, but a moderate risk that breeding in the Hunter and Central Tablelands LLS areas will maintain current population levels during autumn.

Riverina
Riverina and Murray Local Land Services

Locusts and conditions

  • The locust population remained at low densities during January. There have been no locust reports.
  • Surveys of the eastern Riverina in mid-January identified Isolated density adults in the Corowa, Deniliquin, Narrandera, Hay and Wagga districts.
  • There was light-moderate rainfall (<20-40 mm) in eastern Riverina during 8–14 January. Pasture vegetation remains dry in most districts.

Forecast

  • Locust numbers are likely to remain at low levels during February and March, given the current background population and limited breeding opportunities.
  • Moderate-heavy rainfall would be necessary during February for any significant breeding to occur. However, any egg laying would likely only produce low density nymphs in March.
  • There is a very low probability of significant immigration from other regions during February or autumn.

Risks

  • There is a low risk of a widespread infestation developing during February or autumn.

Far West and Far Southwest
Western Local Land Services

Locusts and conditions

  • Locusts remained at very low densities during January.
  • Previous surveys in December identified very few locusts in these regions. Isolated–Scattered density adults were recorded in the Bourke district in December.
  • There was a report of adult locusts at Numerous density along the roadside near Brewarrina in late January.
  • The Fowlers Gap and White Cliffs light traps recorded no locusts during January.
  • There was localised light rainfall (<20 mm) in the Tibooburra and Broken Hill districts during the first and last weeks of January. Pasture vegetation remains very dry in most areas.

Forecast

  • Given the very low current population level and ongoing dry habitat conditions in most areas, locust numbers are likely to remain low during February and March.
  • Any nymphs surviving from sporadic breeding after December rainfall in the Far Southwest will fledge during February. Without further rainfall these would only contribute to maintaining low overall adult densities in autumn.
  • There is a very low probability of significant immigration from other regions during February or autumn.

Risks

  • There is a low risk of a widespread infestation developing during February or autumn.

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 locust population level is expected to have remained very low during January. No surveys were conducted and there were no reports of locust activity.
  • Previous surveys in December recorded very few adults and no nymphs were detected.
  • No locusts were recorded at the Birdsville or Nooyeah Downs light traps during January.
  • There was moderate–heavy rainfall (20->40 mm) in Barcoo, Quilpie and Bulloo shires at the end of January and early February. Vegetation remained very dry during January but will become green in those areas in February.

Forecast

  • Locust numbers are expected to remain low during February and March, given the previous very low population level and continued dry habitat conditions. The rainfall in late January will produce a vegetation response during February and this is likely to initiate some sporadic breeding. This would produce low density nymphs from late February, but some aggregation of adults is possible in favourable habitats and Numerous density nymphs could develop in localised areas.
  • There is a low probability of immigration from other regions during February or autumn.

Risks

  • There is a low risk of a widespread infestation developing during February or autumn.

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 is expected to have remained generally low during January.
  • No surveys were conducted during January and only Isolated density adults were identified in December.
  • No locusts were recorded at the Longreach light trap during January.
  • There was moderate–heavy (20->40 mm) rainfall in these regions at the end of January and early February, associated with a tropical low pressure. Totals >200 mm were recorded in some locations in northern shires. Vegetation remained very dry in most areas, but will respond to the heavy rainfall and become green during February. A sustained growth response is likely in areas of the Northwest region.

Forecast

  • Locust numbers are likely to remain generally low during February and March, despite the breeding opportunities that improved habitat conditions will create. Given the very low current population level, any egg laying only likely to produce low density nymphs. Hatching could commence in late February and nymphs will develop during March. A moderate increase in adult numbers to Scattered–Numerous densities is likely in localised areas during April.
  • There is a low probability of significant immigration from other regions during February or autumn.

Risks

  • There is a low risk of a widespread infestation developing during February or autumn.

Central Highlands
Central Highlands and Isaac Regional Council

Locusts and conditions

  • The locust population is expected to have remained generally low during January.
  • No APLC surveys were conducted. Low density late instar nymphs were reported by Biosecurity Queensland staff in mid-January in the Emerald area of Central Highlands RC area.
  • There was patchy moderate–heavy storm rainfall (20->40mm) in the eastern part of the Isaac Regional Council (RC) area in mid-January and again at the end of the month.

Forecast

  • The locust population level is likely to remain generally low during February and March. Storm rainfall could initiate continued sporadic low density breeding.  Nymphs could develop in localised areas, but densities are likely to remain generally low.
  • There is a low probability of immigration from other regions during February or autumn.

Risks

  • There is a low risk of a widespread infestation developing during February or autumn.

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

Locusts and conditions

  • The locust population level is expected to have remained generally low in these regions. No survey was conducted and there have been no reports.
  • Previous survey in December recorded Isolated–Scattered density adults in Paroo Shire and only occasional adults in other areas.
  • There was no significant rainfall in these regions during January.

Forecas

  • The locust population is likely to remain generally low during February and March. Localised breeding was possible in some areas in late December and any surviving nymphs will fledge during February. This could contribute to a small increase in overall numbers to Scattered density in some areas.
  • Further breeding is unlikely during February unless there is moderate–heavy rainfall.
  • There is a low probability of immigration from other regions during February or autumn.

Risks

  • There is a low risk of a widespread infestation developing during February or autumn.

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

  • Locust population densities are expected to have remained very low during January. There were no reports.
  • The Dulkaninna and Oodnadatta light traps did not record any locusts during January.
  • There was no significant rainfall in these regions during January. Ground vegetation remains very dry.

Forecast

  • The locust population level is likely to remain very low in these regions during February and March. The current very low numbers and dry habitats present limited opportunities for any breeding.
  • There is a low probability of migrations into these regions during February or autumn.

Risks

  • There is a low risk of a widespread infestation developing during February or autumn.

Murray Valley, Mt Lofty Ranges & Southeast Region

Locusts and conditions

  • Locust densities are expected to be very low in these regions. No surveys were conducted and there have been no reports.
  • There was no significant rainfall in these regions during January. Ground vegetation is very dry.

Forecast

  • The locust population level is likely to remain low during February and March.
  • There is low probability of any immigration from other regions during February or autumn.

Risks

  • There is a low risk of a widespread infestation developing during February or autumn.

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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Northwest & North Central Victoria

Locusts and conditions

  • The locust population level is expected to have remained low in inland districts during January.
  • There were continued reports of locusts in the Omeo–Swifts Creek area and adjacent valleys during January. Agriculture Victoria staff confirmed locusts were mixed with several grasshopper species and comprised only a small proportion of the higher densities reported in some areas.
  • There was no significant rainfall in these regions during January. Ground vegetation is becoming dry in most areas.

Forecast

  • Locust numbers are likely to remain low in inland areas during February and March. Given the very low background population in most areas, any breeding after the heavy rainfall in December would only contribute to maintaining the overall low density population.
  • The locust population confined in the Omeo Valley area is unlikely to present a significant migration risk to other regions in Victoria. A second generation of nymphs could develop there during February after heavy rainfall in late December.
  • There is a low probability of significant immigration from other states during February or autumn.

Risks

  • There is a low risk of a widespread infestation developing during February or autumn.

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.

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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
diapauseDormancy in autumn laid eggs avoiding winter 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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