Locust Bulletin January 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 December 2018 and outlook to March 2019

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Australian plague locust - Chortoicetes terminifera

The locust population level remains very low over most regions in eastern Australia. A small increase in population numbers was detected in some areas during December, which is usual after the fledging of a spring generation, but overall densities were low. Medium density adults developed in restricted areas of Central West New South Wales and Gippsland in Victoria. Habitat conditions also remained dry in most regions during December, but rainfall in inland New South Wales, Queensland and Victoria in the middle of the month produced a green vegetation response in some regions.

Survey in the Central West, Far West and Far Southwest regions of New South Wales recorded only occasional adult locusts in most areas. Low density locusts were identified in the Bourke, Warren and Condobolin districts. Following a report from the Lake Cargelligo district, medium density adults and residual late instar nymphs were identified over the same small area where a population was recorded in autumn. There was moderate–heavy rainfall in the Far Southwest, Central West and Riverina regions in mid-December.

Survey of the Central West, South Central and Central Highlands regions of Queensland identified low density adult locusts in the Blackall–Longreach, Augathella–Mitchell and Cunnamulla areas, with only occasional adults in other areas. Very few locusts were detected in Southwest Queensland. There was localised moderate–heavy rainfall in the Central West, South Central, Central Highlands and Darling Downs regions in mid-December.

Previous surveys in South Australia recorded no locusts and habitat conditions were very dry. There was localised light–moderate rainfall in parts of the Northwest region during the first half of December, but habitat conditions remain very dry in most areas.

No surveys were conducted in Victoria, but locust numbers are expected to have remained low in inland habitats. Reports from the Omeo–Swifts Creek area in East Gippsland in late December have been confirmed by Agriculture Victoria as medium–high density adult locusts. The population in this area has developed over several seasons. Widespread moderate–heavy rainfall in the North Central and Northwest regions in mid-December provided suitable conditions for some low density breeding, but habitats will dry out rapidly during January.

The outlook for the rest of summer is for population densities to remain generally low in inland eastern Australia. Small population increases are likely in localised areas of favourable habitat. The Bureau of Meteorology seasonal rainfall outlook for January to March 2019 indicates continued below average rainfall and high temperatures over most of the species range. However, localised heavy rainfall events can provide breeding opportunities resulting in subsequent nymph populations. Given the very low current population numbers in all surveyed regions, there is a low probability of successful breeding producing high density populations during January or February.

There is a low probability of a widespread infestation developing in any region during summer or March.

10 January 2019

Spur-throated locust - Austracris guttulosa

The population level of this species remained very low in areas surveyed during December. There were no reports. Surveys in late November and December identified only Isolated density adults in the Queensland Central Highlands and the Longreach–Blackall area of the Central West region. No locusts were recorded in Southwest Queensland or in New South Wales. No nymphs have been detected by surveys.

Although rainfall in the Central West, Central Highlands and South Central Queensland could have initiated some breeding during November and December, nymphs and eggs are susceptible to desiccation and high nymph mortality can occur if habitats become dry. The low adult population numbers in surveyed regions are unlikely to produce widespread nymphs during summer, even if there is average wet season rainfall. 

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

Migratory locust - Locusta migratoria

Surveys in December did not detect this species, although occasional adults were recorded in the Southern Central Highlands in October. Rainfall in the Central Highlands, Central West and South Central Queensland during December could allow low density breeding and the maintenance of background population numbers.

There is a low risk of a widespread infestation developing during summer or March.

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 December to 31 December 2018

Australian plague locust (Chortoicetes terminifera)

Situation in December 2018 and forecast to March 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 density across most areas in these regions. Medium density adults were identified in a localised area in the Lake Cargelligo district.
  • Surveys in late November and early December recorded occasional Isolated density adults in the Narrabri–Moree and Weilmoringle areas of the Northwest Plains, and in the Nyngan–Carinda, Warren–Tottenham–Condobolin areas of the Central West.
  • Following a landholder report, Numerous density adults and occasional late instar nymphs were recorded in a restricted area near Euabalong, north of Lake Cargelligo. This localised higher density population has persisted since last summer and most adults are likely to have fledged from spring hatchings.
  • There was widespread moderate rainfall (20-40 mm) during 8–14 December, with heavy falls (>40 mm) in parts of the Central West. There was further moderate–heavy rainfall (20->40 mm) in eastern parts of the Northwest Plains and Central Tablelands during 15–21 December.

Forecast

  • Despite improvement in habitat conditions in some areas during November and December, no large population increase is expected during January or February. Sporadic breeding could produce localised low density nymphs during January, but these are only likely to maintain low overall adult population levels.
  • There is a very low probability of significant immigration from other regions during summer.

Risks

  • There is a low risk of a widespread infestation developing during summer or March.

Riverina
Riverina and Murray Local Land Services

Locusts and conditions

  • The locust population was at very low density during spring. There have been no locust reports.
  • Previous survey of the western Riverina identified only occasional adults and no nymphs were detected.
  • There was widespread light-moderate rainfall (<20-40 mm) across the region during mid-December, with localised heavy storms (>40 mm) in the southern Riverina. Pasture vegetation remains dry in most districts.

Forecast

  • Locust numbers are likely to remain at low levels during January and February, given the current population level and limited breeding opportunities. Any breeding in November or December is likely to produce only low density nymphs that would contribute to low overall adult numbers during summer.
  • There is a very low probability of significant immigration from other regions during summer.

Risks

  • There is a low risk of a widespread infestation developing during summer or March.

Far West and Far Southwest
Western Local Land Services

Locusts and conditions

  • Locusts were at very low densities during spring and December. There were no reports of locust activity.
  • Survey in mid-December identified no locusts in the Broken Hill–Menindee–Wilcannia area and only occasional adults in the Tibooburra–Milparinka–Fowlers Gap area. Isolated–Scattered density adults were recorded in the Bourke district in early December.
  • The Fowlers Gap and White Cliffs light traps recorded no locusts during December.
  • There was moderate rainfall (20-40 mm) in the Far Southwest in mid-December, with some heavy falls (>40 mm) in the Balranald area. Pasture vegetation remains very dry in other areas.

Forecast

  • Given the very low current population level and dry habitat conditions in most areas, locust numbers are likely to remain low during January and February.
  • Sporadic breeding was possible following rainfall in mid-December in the Far Southwest. Low density nymphs could develop in the Balranald–Wentworth district during January. Without further rainfall these would only contribute to maintaining low overall adult densities in summer.
  • There is a very low probability of significant immigration from other regions during summer.

Risks

  • There is a low risk of a widespread infestation developing during summer or March.

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 was very low in areas surveyed during December. There were no reports.
  • Surveys in Bulloo and Quilpie shires in mid-December recorded only occasional Isolated density adults and no nymphs were detected.
  • No locusts were recorded at the Birdsville or Nooyeah Downs light traps during December.
  • There was patchy light–moderate rainfall (<20-40 mm) in northern Barcoo Shire shires during mid-December. Vegetation remains very dry in most areas.

Forecast

  • Locust numbers are expected to remain very low during January and February, given the previous low population level and dry habitats. High mortality is likely among any nymphs produced after sporadic breeding in November or December. Moderate–heavy rainfall would be necessary during January and February to improve nymph survival rate in most areas.
  • There is a low probability of immigration from other regions during summer.

Risks

  • There is a low risk of a widespread infestation developing during summer or March.

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 low in areas surveyed during December.
  • Isolated density adults were identified in the Longreach and Blackall-Tambo Regional Council (RC) areas during December. No nymphs were detected. The Northwest region was not surveyed.
  • No locusts were recorded at the Longreach light trap during December.
  • There was widespread light–moderate rainfall (<20–40 mm) in the Central West during mid-December, with some localised heavy falls (>40 mm). The Northwest region received only patchy light rainfall. Vegetation remains very dry in most areas.

Forecast

  • Locust numbers are likely to remain low during January and February. Given the very low current population level and poor habitat conditions in most areas, any breeding is only likely to maintain the population at background levels.
  • There is a low probability of immigration from other regions during summer.

Risks

  • There is a low risk of a widespread infestation developing during summer or March.

Central Highlands
Central Highlands and Isaac Regional Council

Locusts and conditions

  • The locust population level remained very low in surveyed areas. There were no reports.
  • Surveys in late November and early December identified occasional Isolated density adults in Isaac and Central Highlands RC areas. No nymphs were detected.
  • There was patchy moderate–heavy storm rainfall (20->40mm) in mid-December in Isaac RC area, with only light rainfall in Central Highlands RC area. Pasture vegetation became dry in most areas during December.

Forecast

  • The locust population level is likely to remain generally low during summer. Summer storm rainfall could initiate some sporadic low density breeding and nymphs might develop in localised areas of the Central Highlands RC area.
  • There is a low probability of immigration from other regions during summer.

Risks

  • There is a low risk of a widespread infestation developing during summer or March.

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

Locusts and conditions

  • Locust population levels are generally low in these regions. There have been no reports.
  • Survey in early December detected no locusts in the Charleville area, but Isolated–Scattered density adults were recorded in the Cunnamulla area. Previous surveys in late November identified Isolated density adults in Murweh Shire and in Maranoa, Western Downs and Goondiwindi RC areas.
  • There was moderate rainfall (20-40 mm) in Paroo and Murweh shires, and in Western Downs, Maranoa and Goondiwindi RC areas during mid-December. There was further moderate rainfall in Goondiwindi RC area during 16–22 December, with some heavy storms (>40 mm).

Forecas

  • The locust population is likely to remain generally low during January and February. Some sporadic breeding may be initiated in areas that received rainfall in December. Further rainfall in January could maintain favourable habitat conditions for nymph development and egg laying. An increase in adult population to Numerous density is possible in some areas in February.
  • There is a low probability of immigration from other regions during summer.

Risks

  • There is a low risk of a widespread infestation developing during summer or March.

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 December. There were no reports.
  • The Dulkaninna and Oodnadatta light traps did not record any locusts during December.
  • There was light–moderate rainfall (<20-40 mm) in the parts of the Northwest region during mid-December. Ground vegetation is very dry in most areas.

Forecast

  • The locust population level is likely to remain very low in these regions during summer. The current very low numbers and dry habitats present limited opportunities for successful breeding. Parts of the Northwest region that received rain periods during November and December could support localised low density nymph development, but much of the western part of the region is not suitable locust habitat.
  • There is a low probability of migrations into these regions during summer.

Risks

  • There is a low risk of a widespread infestation developing in summer or March.

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 light rainfall in the Southeast and Murray Valley regions during mid-December. Vegetation in locust habitat area id mostly dry.

Forecast

  • The locust population level is likely to remain low during summer.
  • There is low probability of any immigration from other regions during summer.

Risks

  • There is a low risk of a widespread infestation developing during summer or March.

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 December.
  • There were several reports of high numbers of adult locusts in the Omeo–Swifts Creek area during December after the fledging of a spring generation. Agriculture Victoria staff confirmed adults mixed with several other grasshopper species at Numerous–Concentration density in localised areas. There has been a persistent population in the grassland valleys of this district for several years.
  • There was widespread moderate–heavy rainfall (20->40 mm) in North Central and Northwest Victoria during mid-December. Pasture vegetation remains dry in the Northwest and most areas of the North Central region.

Forecast

  • Locust numbers are likely to remain low in inland areas during January and February. Rainfall in mid-December could have initiated some sporadic breeding and localised low density nymphs might develop during January. Given the very low background population in most areas, this would only contribute to the overall low density population.
  • The higher density population confined in the Omeo Valley area is unlikely to present a significant migration risk to other regions in Victoria. Adults are likely to have commenced breeding after rainfall during December and a nymph generation is possible in late January. If swarm egg laying occurred, high density nymphs could develop in localised areas.
  • There is a low probability of significant immigration from other states during January or February.

Risks

  • There is a low risk of a widespread infestation developing during summer or March.

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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