Locust Bulletin March 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 February and outlook to May 2019

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Australian plague locust - Chortoicetes terminifera

The locust population level remains low over most inland regions in eastern Australia. Moderate population increases were identified in Central West and Northwest Plains regions of New South Wales in early February. Locust numbers remained low in surveyed areas of Far West and Far Southwest New South Wales. Surveys indicated a very low population in part of Southwest Queensland, but access was restricted in western Queensland due to floodwaters. 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 of the Central West and Northwest Plains regions of New South Wales identified up to medium density adult locusts in the Coonamble district and low density adults in most other areas. Surveys of the Far West and Far Southwest regions indicate continuing low density adult populations and no nymphs were detected. There were no reports from the Hunter and Central Tablelands regions after early February.

Limited surveys in Queensland identified occasional adults in the Southwest and Central West regions, but medium density adults with developing eggs were recorded south of Longreach in late February. This indicates breeding is occurring and could be more widespread in favourable habitats resulting from heavy rainfall in early February. Sporadic egg laying is likely in the Northwest, Central West and Southwest regions. Locust numbers are expected to have remained low in the South Central and Central Highlands regions.

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

In Victoria, locust numbers are expected to have remained very low in inland habitats. The population in the Omeo Valley area in East Gippsland persisted during February. Late instar nymphs from a second generation were identified near Swifts Creek in in early February.

The autumn outlook is for continuing low population densities in most regions of inland eastern Australia. Green vegetation in Northwest, Southwest and Central West Queensland will have initiated sporadic breeding in late February, which will continue during March. An autumn nymph generation, mostly at low densities, is likely to develop in those areas during March, followed by fledging in late March and April. Localised high density nymphs are possible in restricted locations. An overall increase in adult numbers to medium densities is likely in these regions in late autumn, but these are unlikely to present a significant migration risk or produce a large subsequent nymph population. The adult population currently in Central West and Northwest New South Wales are likely to decline as habitats become dry, and no significant autumn breeding is likely in the absence of heavy rainfall during March. Residual populations in the Central Tablelands and Hunter Valley regions will also decline during autumn, but sporadic egg laying is possible. The Bureau of Meteorology seasonal outlook for March to May 2019 indicates continued above average temperatures and below average rainfall in New South Wales and Queensland. There is a low probability of high density populations developing in inland regions of New South Wales, South Australia or Victoria during autumn. There is a low probability that autumn egg laying will produce high density nymph populations during spring in inland regions.

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

6 March 2019

Spur-throated locust - Austracris guttulosa

The population level remained very low in areas surveyed during summer. Limited surveys were conducted in Queensland during February and the species was not detected in Central West or Southwest Queensland, or in New South Wales.

The heavy rainfall in the Northwest, Central West and Gulf regions of Queensland at the start of February will provide suitable habitat for widespread breeding during autumn. Locust habitats in the Central Highlands region are mostly dry. Adult females can produce several pods and egg laying is often initiated after rainfall. However, the very low known adult population prior to the rains and late commencement of breeding indicates that a large autumn nymph population is unlikely. Hatchings could commence during March and nymphs would fledge in late April and May. Nymphs and eggs are susceptible to desiccation and high nymph mortality is likely if habitat conditions become dry.

There is a low risk of a widespread infestation developing during 2019.

Migratory locust - Locusta migratoria

This species has not been detected since October, when very low numbers were recorded in the southern Central Highlands region of Queensland. Rainfall in parts of Central West and Northwest Queensland in early February could have initiated low density breeding that would contribute to maintaining overall low population densities.

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

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 February and forecast to May 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

  • There was a moderate increase in adult population level in the Central West and Northwest Local Land Services (LLS) regions in early February. Numerous density adults were recorded in the Coonamble district.
  • Surveys during February identified Scattered–Numerous density adults in the Coonamble–Collie–Baradine area. The higher adult numbers in the Coonamble area are likely the result of local movements to areas with green vegetation. There was patchy moderate rainfall (20-40 mm) in the Coonamble–Dubbo area in the second half of January and some green vegetation by mid-February. Isolated–Scattered density adults were recorded in the Nyngan, Narromine and Tottenham districts.
  • In Northwest LLS, Isolated–Scattered density were identified in the Walgett, Narrabri, Moree, Gunnedah and Coonabarabran districts, representing a small increase in numbers over recent months. Present density late instar nymphs were detected at one location near Coonabarabran.
  • There were no further reports after the first week of February from the areas in the northern Central Tablelands and Hunter LLS areas where locusts developed during January. Although nymphs as well as adults were identified by LLS staff in January, numbers appear to have declined and become less visible during February. Several other species, including Gastrimargus musicus, were mixed with locusts at many locations.
  • There was light–moderate rainfall (<20-40 mm) in the Trangie–Nyngan–Condobolin area of the Central West LLS during the first half of February. There was some localised green vegetation in these areas in late February, but conditions in most areas remain dry.

Forecast

  • Localised low density breeding is likely in areas with residual green vegetation. Any aggregation and higher density breeding will depend on the distribution of rainfall in March. A small proportion of any eggs laid in early March in the Central West or Central Tablelands would enter diapause dormancy. The majority of eggs laid from mid-March to mid-April will diapause and not hatch until September. Hatching of diapause eggs in the Northwest Plains usually commences earlier in late August. At this stage, only low numbers of nymphs, at Present–Numerous densities are likely to develop in spring.
  • Some sporadic autumn breeding is also possible in those districts of the Central Tablelands and Hunter LLS areas where adults persist. The level of autumn egg laying and subsequent spring nymph population densities will depend on autumn rainfall distribution.
  • There is evidence of some migratory movements during February and there is a moderate probability of low density redistributions in these regions continuing during autumn. There is a low probability of significant immigrations from other regions during autumn, but some low density movements to the Riverina or Far West are possible.

Risks

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

Riverina
Riverina and Murray Local Land Services

Locusts and conditions

  • The locust population is expected to have remained at low densities during February. There were no locust reports.
  • Previous survey of the eastern Riverina in January identified only occasional adults in most areas.
  • There was patchy light-moderate rainfall (<20-40 mm) in the eastern Riverina during the first two weeks of February. 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 autumn or spring.

Far West and Far Southwest
Western Local Land Services

Locusts and conditions

  • Locusts remained at very low densities in most areas surveyed during February. A small increase in adult numbers was detected in part of the Far Southwest region in early February.
  • Surveys of the Far Southwest identified Isolated–Scattered density adults in the Wilcannia–Ivanhoe area. Previous survey in December identified very few locusts in that area. Only occasional Isolated density adults were recorded in the Menindee–Broken Hill area.
  • Surveys of the Far West region in mid-February recorded very few adults in the White Cliffs, Tibooburra Wanaaring, Brewarrina and Bourke districts. Scattered density adults were recorded near Bourke.
  • The Fowlers Gap and White Cliffs light traps recorded no locusts during February.
  • There was localised light–moderate rainfall (<20-40 mm) in the Cobar and Ivanhoe districts during the first half of February. Pasture vegetation remains very dry in most areas.

Forecast

  • The very low current population level and ongoing dry habitat conditions in most areas indicate that locust numbers are likely to remain low during autumn.
  • Only very low density egg laying is possible in most areas and only occasional nymphs are therefore expected in spring. The majority of any eggs laid from mid-March to mid-April would enter diapause dormancy. Hatching commences in late August in the Far West and mid-September in the Far Southwest.
  • There is a very low probability of significant immigration from other regions during autumn.

Risks

  • There is a low risk of a widespread infestation developing during autumn or 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 locust population level remained low in areas surveyed during February, but access to many areas was prevented by flooding. There were no reports of locust activity.
  • Surveys of Bulloo Shire in mid-February recorded only occasional adults and no nymphs were detected.
  • No locusts were recorded at the Birdsville or Nooyeah Downs light traps during February.
  • There was moderate–heavy rainfall (20->40 mm) in Barcoo, Quilpie, Bulloo and Diamantina shires at the start of February. Ground vegetation became green in those areas during February. Floodwaters passed down the Cooper Creek and Diamantina River in late February, which will produce further vegetation growth during autumn.

Forecast

  • Locust numbers are expected to remain generally low during autumn. However, areas that received heavy rainfall have provided suitable vegetation and soil conditions for locust breeding, particularly in Barcoo, Quilpie and northern Diamantina shires. Only sporadic, low density egg laying is likely given the very low prior population level. Egg laying could have commenced in mid-February and is likely to continue during March. Floodwaters passing into southern areas will produce localised favourable habitats in autumn that will persist into winter.
  • Any eggs laid in February will hatch from mid-March and low density nymphs are likely in some areas. Numerous or higher density nymphs could develop in restricted locations. The majority of eggs laid from mid-March to mid-May will enter diapause dormancy. These would commence hatching in mid-August. Adults can lay several times in good habitat conditions and Numerous density nymphs could develop in localised areas in September, but at this stage high density nymphs or bands are unlikely.
  • There is a low probability of significant immigration from other regions during autumn.

Risks

  • There is a low risk of a widespread infestation developing during autumn or 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 was low in surveyed areas and is expected to have remained generally low throughout these regions.
  • Limited survey were conducted during February because of access restrictions due to flooding. Isolated density adults were identified in Longreach RC area. However, Numerous density adults were recorded near Stonehenge in late February and sampled females contained 4 mm developed eggs. Egg laying was therefore likely in the area.
  • No locusts were recorded at the Longreach light trap during February.
  • There was moderate–heavy (20->40 mm) rainfall in these regions at the end of January and the start of February, associated with a tropical low pressure weather system. Totals >200 mm were recorded in some locations in northern shires. Vegetation became green during February and sustained growth response is likely in the Northwest and northern Central West regions during autumn.

Forecast

  • Locust numbers are likely to remain generally low during March, but a nymph generation will develop in some areas. Egg laying could have commenced in late February, but the very low prior population level suggests most would have been be at low densities. Adults can lay several times in good habitat conditions and egg laying is likely to continue during March. Aggregation and localised high density egg laying is possible in some areas.
  • Most eggs laid during February and early March will hatch. Hatching could commence in mid-March and continue into April.  A proportion of eggs laid after mid-March will enter diapause dormancy and hatch in August and September. Most hatchings will be at low densities, but some Numerous or higher density nymphs could develop in localised areas of the Northwest and in northern shires and Longreach LLS in the Central West during late March or April. A moderate increase in adult numbers to Numerous densities is likely in localised areas during April, with higher densities possible in some locations.
  • There is a low probability of significant immigration from other regions during autumn. Increased adult population numbers in late autumn are unlikely to pose a migration risk to regions in NSW or South Australia.

Risks

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

Central Highlands
Central Highlands and Isaac Regional Council

Locusts and conditions

  • The locust population is expected to have remained generally low during February.
  • No APLC surveys were conducted and there were no reports.
  • There was light rainfall (<20 mm) in the Isaac Regional Council (RC) area in the first week of February and further patchy storm rains in late February. There was very light rainfall (<10 mm) in central Highlands RC area during February. Pasture vegetation is dry in most areas.

Forecast

  • The locust population level is likely to remain generally low during autumn. Any storm rainfall during March could initiate sporadic low density breeding.  Nymphs could develop in localised areas in April, but densities are likely to remain generally low. Most eggs laid during April will enter diapause dormancy and hatch from late August. There is a low probability of a large population increase during autumn or spring.
  • There is a low probability of immigration from other regions during autumn.

Risks

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

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 low in these regions. No survey was conducted and there have been no reports.
  • Previous surveys recorded only occasional adults.
  • There was no significant rainfall in these regions during February. Pasture vegetation is very dry in most areas.

Forecast

  • The locust population is likely to remain low during autumn, after dry conditions since January and low prior population density. Without moderate–heavy rainfall during March, opportunities for any breeding will be limited.
  • The majority of any eggs laid after mid-March will enter diapause dormancy and not hatch until September.
  • There is a low probability of immigration from other regions during autumn.

Risks

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

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

Forecast

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

Risks

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

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 February. Ground vegetation is dry in most areas.

Forecast

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

Risks

  • There is a low risk of a widespread infestation developing during autumn or 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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Northwest & North Central Victoria

Locusts and conditions

  • The locust population level is expected to have remained low in inland districts during February.
  • There were further reports of locusts in the Omeo–Swifts Creek area in early February. Agriculture Victoria staff confirmed late instar locust nymphs near Swifts Creek, although locusts were mixed with several grasshopper species in some areas.
  • There was light rainfall (<20 mm) in Northwest Victoria during the first week of February and light–moderate falls in eastern Victoria in mid-February. Ground vegetation is dry in most areas.

Forecast

  • Locust numbers are likely to remain low in inland areas during autumn. Given the very low background population in most areas, any sporadic breeding will be at low density. The majority of eggs laid from early March will enter diapause dormancy. These will hatch from early October in the north to mid-October in southern areas.
  • The locust population in the Omeo Valley is likely to persist during March and autumn egg laying is likely in some areas. At this stage the size of the autumn breeding locust population relative to other species present in the area is uncertain, but if aggregation and egg laying occur, nymphs could develop at Numerous or higher densities in some areas during spring.
  • There is a low probability of significant immigration from other states during autumn.

Risks

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

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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
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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