Locust Bulletin November 2017

​​​​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 October and outlook to January 2018

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Australian plague locust - Chortoicetes terminifera

Locust densities identified during September and October are among the lowest spring population levels on record for these months. Surveys recorded very few adults in South Australia, Queensland and New South Wales. Rainfall during winter and September was well below average over most of inland eastern Australia, and habitat conditions remained very dry. However, since the end of September there has been moderate–heavy rainfall in several regions, with some areas recording several significant rain events. Vegetation has responded to these rains and this is likely to initiate low density locust breeding in numerous areas. Large population increases are unlikely during November and December, given the very low background spring population levels.

In New South Wales, survey of the southern Central West and northern Riverina identified only occasional low density adults. No nymphs were detected. Rainfall in the Northwest, Central West and part of the Far West regions may have initiated some low density egg laying.

Survey was conducted in Southwest Queensland in mid-October. Very few adults were identified and no nymphs were detected. Heavy rainfall in the Central Highlands and South Central regions, as well as in Quilpie and Bulloo Shires of the Southwest, is likely to have initiated some low density egg laying.

In South Australia, surveys in late September identified only occasional adult locusts in the Far North, Northwest and Northeast regions. Heavy rainfall in the Oodnadatta area is likely to have initiated some low density egg laying.

There was no survey or report information from Victoria during October. Any spring hatchings will have occurred during the month and the locust population is likely to remain at a low level.

Sporadic hatchings have continued in parts of the of Western Australian wheatbelt. The Department of Primary Industries and Regional Development received reports of mid-instar nymphs from several districts in the Central Agricultural Region.

The outlook for the remainder of 2017 is for population densities to remain generally low in all regions of inland eastern Australia. Breeding in areas that received heavy rainfall during October is likely to produce mostly low density nymphs during November. Fledging of nymphs in December would result in only moderate regional adult population increases. The probability of a summer nymph generation, which could result in significant population increases in January and February, will depend on the distribution of moderate–heavy rainfall during December. Given the current very low population densities, there is a low risk of widespread regional infestations developing during summer. However, seasonal rainfall forecast models suggest an average rainfall expectation over coming months and even isolated heavy rainfall events can result in localised large population increases.

3 November 2017

Spur-throated locust - Austracris guttulosa

There is a widespread low density population of adults in inland Queensland. Surveys in September and October identified Isolated–Scattered density adults in the Southwest, Central West, South Central and Central Highlands regions. Occasional adults were recorded in the Far North and Northwest regions of South Australia and in Far West New South Wales.

Migrations and local swarm movements of over-wintered adults often occur during spring and early summer. Breeding does not usually commence until the onset of the northern wet season. Rainfall during October, particularly in the Queensland Central Highlands, northern Central West and South Central regions, has created favourable habitat conditions for the commencement of breeding. Eggs take 3–4 weeks to hatch after laying and nymph development, a further 8–10 weeks. Nymphs are likely to appear in those regions from late November. Females can lay multiple times during summer, usually following significant rainfall. Nymphs of this species do not usually aggregate to form cohesive bands, but can reach densities of 30/m2 in favourable habitats.

There is a low risk of swarms developing or migrating into agricultural regions during the remainder of spring or summer. The likelihood of an overall population increase during 2017-18 will depend on the frequency and persistence of rainfall during the wet season.

Migratory locust - Locusta migratoria

The Queensland Central Highlands and South Central regions were not surveyed during October, but previous survey in September identified occasional low density adults at several locations south of Emerald. Isolated density adults were recorded in the Rolleston and Taroom–Roma areas but no nymphs were detected. Populations of this species are commonly found in these regions and rapid population increases are possible in favourable habitat.  Gregarious populations can occur at local scales and are often associated with forage or cereal cropping.

The heavy rainfall in the Central Highlands and South Central regions of Queensland during October has produced suitable soil and vegetation conditions for breeding. Small gregarious populations could develop in localised areas of these regions during 2017-18. However, there is currently a low risk of a widespread infestation developing during November or summer.

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 October to 31 October 2017 

 

Australian plague locust (Chortoicetes terminifera)

Situation in October 2017 and forecast to January 2018

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 identified locust population remained at low densities during October.
  • Survey of the Narromine–Tottenham–Condobolin district in late October identified only occasional Isolated density adults. Survey of the Central West and Northwest Local Land Services (LLS) areas in late September identified only occasional Isolated density adults in most areas. Isolated–Scattered densities were recorded in the Narromine–Collie and Quambone districts.
  • Hatching of autumn laid eggs will have finished. Any residual quiescent eggs in dry soil will have completed development after rainfall and also hatched.
  • A report from the Peak Hill area was identified as low densities of mixed grasshopper species.
  • There was moderate rainfall (20-40 mm) in the Moree district during the first week of October and widespread moderate–heavy rainfall (20->40 mm) throughout the Central West and Northwest Plains regions during 7–14 October. There was further widespread moderate rainfall during 15–21 and 22–28 October. Pasture vegetation is now green in most areas.

Forecast

  • The change in habitat conditions provided opportunities for egg laying after mid-October. However, breeding by the current low regional population is only likely to produce nymphs at low–medium densities. Habitat conditions are now favourable over large areas in these regions, but nymphs are more likely to develop in the eastern parts of the Central West and Northwest LLS areas.
  • Hatchings from local breeding could commence in early November and the majority of any nymphs would fledge during December. A moderate increase in regional adult population is likely from the current low level.
  • The likelihood of a large population increase as a result of a further generation developing during summer will be primarily influenced by the distribution of rainfall during November and December.
  • There is a low probability of significant immigration from other regions during November or December.

Risks

  • There is a low risk of a widespread infestation developing before 2018.

Riverina
Riverina and Murray Local Land Services

Locusts and conditions

  • The locust population level remained very low in the areas surveyed during October. There were no reports of locust activity.
  • No locusts were recorded during survey of the West Wyalong–Narrandera–Lake Cargelligo area in late October.
  • There was light–moderate rainfall (<20–40 mm) in eastern areas of the region during 8–14 October, with further light falls during 15–21 October. There has been patchy pasture growth in the eastern Riverina.

Forecast

  • Improved habitat conditions in the eastern Riverina and Murray LLS areas could have initiated some sporadic low density breeding. However, given the current low population level, only low density nymphs are likely to result during November and drying conditions will increase the rate nymph mortality. Habitats in the western parts of the region remain largely unsuitable for locust breeding.
  • Local breeding is only likely to result in a small population increase from very low background numbers during November and December.
  • There is a low probability of significant immigration from other regions during November or December.

Risks

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

Far West and Far Southwest
Western Local Land Services

Locusts and conditions

  • No locusts were detected during October. There were no reports of locust activity.
  • Several districts of the Far West region were surveyed in late October. No locusts were recorded in the Broken Hill, Tibooburra, Wanaaring or White Cliffs areas. This represents the lowest October population level on record for the region and is largely the result of the low autumn population and very low rainfall during winter and September.
  • The Fowlers Gap and White Cliffs light traps recorded no locusts during October.
  • There was patchy light–moderate (20-40 mm) storm rainfall in both regions during the second week of October and further moderate falls, along with locally heavy storms, during the third week of the month. Pasture vegetation is becoming green in some areas.

Forecast

  • Improved habitat conditions could have initiated some localised breeding that would produce low density nymphs during November. However, given the very low background population level, this is unlikely to result in a significant adult population increase in December.
  • The likelihood of a large population increase as a result of a further generation developing during summer will be primarily influenced by the distribution of rainfall during November and December. Without at least moderate rainfall, dry habitat conditions will limit breeding and increase the rate of nymph mortality.
  • There is a low probability of any significant immigration from other regions during November or December.

Risks

  • There is a low risk of a widespread regional infestations developing during November or summer.

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

  • Only very low numbers of locusts were identified during October. There were no reports of locust activity.
  • Bulloo and Quilpie Shires were surveyed in mid-October. Only occasional Isolated density adults were recorded in the Quilpie–Eromanga area and no nymphs were detected. Some low density hatchings may have occurred during August or September, but very dry habitat is likely to have limited nymph survival.
  • The Birdsville and Nooyeah Downs light traps did not record any locusts during October.
  • There was patchy moderate–heavy storm rainfall (20->40 mm) in Bulloo and Quilpie Shires during 7–14 and 15–21 October. Pasture vegetation has responded in those areas.

Forecast

  • Storm rainfall has created suitable habitat conditions for localised breeding, particularly in the Quilpie–Eromanga area. However, given the very low background population level, this is only likely to produce low density nymphs. Fledging of nymphs is likely to result in a moderate adult population increase in December from the current very low numbers.
  • The likelihood of a large population increase as a result of a further generation developing during summer will be primarily influenced by the distribution of rainfall during November and December.
  • There is a low probability of immigration from other regions during November or December.

Risks

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

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 remained low in areas surveyed during October. There were no reports.
  • Limited survey was conducted in the Longreach Regional Council (RC) area in mid-October. No locusts were identified.
  • The Longreach light trap recorded no locusts during October.
  • There was moderate–heavy rainfall (20->40 mm) in parts of Blackall-Tambo and Barcaldine RC areas during 15–21 October, and heavy falls in parts of Fitzroy Shire at the end of the month.

Forecast

  • Locust population levels are expected to remain low in these regions during November and December.
  • Given the current low adult population densities, local breeding during October is only likely to produce low density nymphs. Fledging of any nymphs during December is unlikely to contribute to a significant adult population increase.
  • A return to dry conditions will reduce nymph survival of any nymphs, so the distribution of rainfall during November and December will influence the likelihood of any large population increases
  • There is a low probability of any immigration from other regions during spring or December.

Risks

  • There is a low risk of a widespread regional infestations developing during November or summer.

Central Highlands
Central Highlands and Isaac Regional Council

Locusts and conditions

  • Locust population density is expected to have remained generally low during October. There were no reports.
  • Previous surveys identified occasional low density adults in several areas.
  • There was moderate heavy rainfall (20->40 mm) throughout the region during the first week of October, and further moderate–heavy rainfall during 15–21 October. Pasture vegetation became green in many areas during October.

Forecast

  • Several periods of heavy rainfall during October have created suitable soil and vegetation conditions for locust breeding, particularly in Central Highlands Regional Council (RC) area and in Banana Shire.
  • Any egg laying during October could produce low–medium density nymphs from early November, which would fledge in December. Localised moderate adult population increases to Scattered–Numerous densities are possible.
  • Rainfall distribution during December will influence the likelihood of any further breeding and population increase during summer.
  • There is a low probability of immigration from other regions during November or December.

Risks

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

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 in these regions, but rainfall during October has produced widespread favourable breeding habitats.
  • No APLC surveys were conducted and there were no reports of locust activity.
  • There was moderate–heavy (20->40 mm) rainfall in the Western Downs, Toowoomba and Goondiwindi Regional Council (RC) areas during the first week of October and further widespread moderate–heavy falls throughout the region during the second week of the month. Murweh Shire and Maranoa RC area received moderate-heavy rainfall and there were light falls in other areas during the last week of the month. Pasture vegetation is green in many areas.

Forecast

  • Locust population levels are likely to remain generally low during November and December. However, rainfall during October may have initiated breeding and low density egg laying in some areas. Nymphs, mostly at low densities, are likely to develop in some areas from mid-November. Fledging will follow during December, resulting in a possible increase in population to Numerous density in localised areas.
  • Rainfall distribution during December will influence the likelihood of any significant population increase during summer.
  • There is a low probability of significant immigration from other regions during November or December.

Risks

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

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 levels are expected to have remained low in these regions during October. Heavy rainfall in parts of the Far North and Northwest regions at the beginning of the month has produced favourable habitat for locust breeding.
  • No APLC survey was conducted during October and there were no reports of locust activity
  • The Dulkaninna and Oodnadatta light traps did not record any locusts in October.
  • There was moderate–heavy storm rainfall (20–>40 mm) around the Oodnadatta area in the Far North and Northwest regions in early October, with some locations receiving >100 mm. There was localised moderate–heavy storm rainfall in the Northwest and Western Agricultural regions, and patchy light falls in the Flinders Ranges, during the second week of the month.

Forecast

  • The locust population level is likely to remain generally low in these regions during November and December. The heavy rainfall in the Oodnadatta area at the start of the month produced favourable soil and vegetation conditions for locust egg laying. However, given the very low population numbers identified prior to the rains, only low density nymphs are likely to result. Hatching could have commenced in late October.
  • It is possible that some adults migrated to the Oodnadatta area from further west or the Northern Territory, which would have increased the breeding population. It is also possible that some eggs from autumn laying remained in quiescence due to low soil moisture. These would have recommenced development after the rain and hatched after mid-October.
  • Fledging of any nymphs in the Far North would commence in late November and result in a moderate increase in adult population level. Vegetation will dry out during November in the absence of further rainfall, which would limit the likelihood of further breeding during December. Conditions remain dry in the Northeast and most areas of the Far North region and the likelihood of any significant population increase during November or December remains low.
  • There is a low probability of significant migrations into these regions during November or December.

Risks

  • There is a low risk of widespread regional infestations developing in November or summer.

Murray Valley, Mt Lofty Ranges & Southeast Region

Locusts and conditions

  • Locust densities are expected to have remained very low. No APLC surveys were conducted and there have been no reports.
  • There was only very light rainfall (<10 mm) in these regions during October.  Pasture vegetation is dry in most areas.

Forecast

  • Locust population levels are likely to remain low during November and summer.
  • There is low probability of any significant immigration during November or December.

Risks

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

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

  • Locust population levels are expected to have remained low in Victoria during October.
  • There has been no APLC survey and no locust reports.
  • There was light–moderate rainfall (<20–40 mm) in eastern areas of North Central Victoria during 8–15 October and light rainfall in the Northwest during the last week of the month.

Forecast

  • Spring hatchings will have occurred during October. Habitat conditions are generally unfavourable for locust breeding and only occasional isolated egg laying is likely during November or December. This is unlikely to result in any significant population increase.
  • There is a low probability of any significant immigration during November or December.

Risks

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

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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