Locust Bulletin December 2016

​​​​​​ISSN 2204-9851

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

General situation in November and outlook to February 2017

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Australian plague locust - Chortoicetes terminifera

Locust population levels remained generally low in most regions during November. However, redistribution and migration resulted in increased adult numbers in Central West New South Wales in mid-November. Nymphs in the localised high density populations in Far Southwest New South Wales and the Flinders Ranges area of South Australia fledged in November, but adults gradually dispersed from those locations and numbers declined to low densities by the end of the month.

Surveys in Central West New South Wales identified an increase in adult numbers to medium densities, following the passage of a low pressure system during 10–12 November. High density adults were subsequently recorded near Tottenham and a small swarm between Collie and Narromine. Adults were recorded a low densities in the Northwest Plains and Riverina. Fledging of nymphs continued throughout November in the area south of Broken Hill, but adult numbers remained relatively constant at medium density until late November.

In Southwest Queensland, medium density adults and occasional nymphs were recorded in parts of Barcoo and Diamantina Shires in late November, despite a widespread nymph population during October. Low density adults and occasional late-instar nymphs were identified in Bulloo, Quilpie and Paroo Shires, and in Longreach and Blackall-Tambo Regional Council areas. Only occasional adults were identified in other areas of South Central Queensland.

In South Australia, medium density adults were recorded in the Hawker–Parachilna and Murnpeowie–Dulkaninna areas of the Far North region and the Oodnadatta–Marla and Coober Pedy–Arkaringa areas of the Northwest region. These populations are likely to be the result of breeding following heavy rainfall in September. Low density adults were recorded in other areas of these regions and in the Northeast region, where nymphs were detected at one location.

Locust populations in Victoria are expected to have remained at a low level, despite any nymphs from a spring generation having fledged during November. There have been no reports of locust activity.

The outlook for December is for localised nymph populations in parts of the southern Central West and Far Southwest New South Wales. Heavy rainfall in those areas during November created favourable habitat conditions for breeding, which is likely to produce nymphs during December, with the possibility of Bands developing in some locations. Fledging would follow in January, but drying vegetation could limit nymph survival and swarm formation is unlikely. Breeding is also possible in limited areas of the Northwest and Far North regions of South Australia in early December. The probability of population increases during summer is dependent on the distribution of moderate–heavy rainfall. The likelihood of lower than average rainfall during December and January may increase nymph mortality and limit opportunities for further breeding. However, even isolated heavy rainfall events can result in population increases during summer. There is currently a low risk of widespread high density infestations developing in any region during summer.

2 December 2016

Spur-throated locust - Austracris guttulosa

There is a widespread medium density adult population throughout the Central West, Northwest, Southwest, Central Highlands and Queensland Gulf regions. Consistent high densities were recorded in northern shires of Northwest and Central West Queensland during spring. Nymphs were recorded in Queensland in October and November. The unseasonal September rainfall in Queensland and green habitat conditions throughout inland regions appears to have initiated early breeding in some areas.

Surveys in October identified consistent Scattered–Numerous density adults in Boulia and Winton Shire, and in Longreach, Blackall-Tambo and Barcaldine Regional Council (RC) areas. Adults were recorded at Isolated–Scattered densities in the Southwest and South Central regions.

November surveys indicate a population increase in Quilpie, Paroo and Murweh Shires, where Scattered–Numerous density adults were recorded. These are likely to have redistributed from populations further north. Isolated–Scattered density adults were identified in Barcoo and Diamantina Shires of Southwest Queensland, along with Present density nymphs at various development stages. Isolated density adults were identified in the Far North, Northwest and Northeast regions of South Australia.

Egg development to hatching in this species takes 3–4 weeks and nymph development a further 8–10 weeks. Females can lay multiple times during summer. Nymphs of this species usually do not aggregate to form bands, but can reach densities of 30 m2 in favourable habitats. The survival of early stage nymphs can be limited in dry conditions.

Dry conditions in areas north of Longreach and the decline of green habitat conditions in Southwest, Central West, South Central and the Central Highlands regions of Queensland are likely to cause increased nymph mortality during December. The probability of an increase in population during 2016–17 has therefore declined. However, a large potential breeding population remains in Queensland and the likelihood of an overall population increase will depend on the consistency of rainfall during the northern wet-season.

Migratory locust - Locusta migratoria

Previous surveys in October identified only occasional low density adults in the southern Central Highlands region of Queensland. This region was not surveyed during November and there were no reports of locust activity. The species was not recorded in other regions. Rapid increases can occur in the Central Highlands and eastern parts of Central West Queensland. Grassland habitats have become mostly dry in these regions. However, variable and contracting green habitats can contribute to local gregarisation of this species.

There is a low probability of widespread gregarious populations developing in the Central Highlands, eastern Central West or South Central regions of Queensland during summer. However, small gregarious populations could develop in localised areas of the Central Highlands.

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

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Australian plague locust distribution 1 November to 30 November 2016

Map of Australian plague locust distribution 1 November to 30 November 2016 

Situation in November and forecast to February 2017

New South Wales

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

Locusts and conditions

  • Redistribution and immigration produced an increase in adult densities in the Central West LLS area, following the passage of a low pressure system in early November.
  • There were several reports of increased locust numbers in the Warren and Tottenham areas on 13 November after storms on 11 November. Wind trajectories on the nights of 10 and 11 November indicate convergence of winds from the north and west. Movements on preceding days could have enabled some immigration from Far West NSW and Southwest or South Central Queensland and an aggregation of locusts within Central West NSW.
  • Surveys on 15 and 16 November identified an increase in overall adult numbers to Scattered–Numerous from the very low densities recorded in late October. Concentration density adults were recorded near Warren and Tottenham, and a small swarm south of Collie. Females sampled at these locations showed egg development at 2–4. The identified swarm had moved by November 18. There was also a small increase in adult numbers in the Coonamble–Carinda area and in the Walgett–Burren Junction areas of Northwest LLS, where Isolated–Scattered density adults were recorded.
  • Surveys in late November in the Lake Cargelligo–Condobolin district identified Scattered–Numerous density adults near Euabalong. No nymphs were detected during surveys.
  • There was light–moderate rainfall (<20–40 mm) in the Central West and Central Tablelands LLS during 8–14 November, with locally heavy falls in some eastern locations. There was light rainfall (<20 mm) in the Moree and Narrabri districts of Northwest LLS during 8–14 November. Pasture vegetation is drying off in many areas, but will remain green in the parts of southern Central West LLS area.

Forecast

  • Egg laying was likely in areas that received moderate–heavy rainfall during 11-12 November. There were locally heavy storm rains in the southern Central West LLS. The Parkes–Condobolin, Peak Hill–Dandaloo, Cumnock–Wellington and Collie–Mendooran areas received moderate–heavy rainfall, which could have initiated localised high density egg laying after mid-November. Hatchings are likely from the end of November and some small Bands could develop in December.
  • Although a December nymph generation is likely in parts of the Central West or Central Tablelands LLS areas, the outlook for drier than normal conditions could result in increased nymph mortality. Low density nymphs could develop in other locations during December. Fledging would follow from mid-January.
  • There is a low probability of significant immigration from other regions during December or January.

Risks

  • There is a low risk of widespread infestations developing during summer, but a nymph generation is likely to develop in parts of the southern Central West during December.

Riverina
Riverina and Murray Local Land Services

Locusts and conditions

  • Locust population level remained low during November, despite fledging of spring generation nymphs and possible immigration from regions to the west.
  • Surveys in late November identified only occasional Isolated density adults in the Hay, Jerilderie and Griffith districts. No nymphs were detected during survey. The low regional population level indicates there was no successful spring nymph generation.
  • There was light–moderate rainfall (<20–40 mm) across the region during 8–14 November, and further light rainfall in Murray LLS area during 22–28 November. Ephemeral pasture vegetation has dried off in most areas, but residual soil moisture has produced summer perennial grass growth in localised areas.

Forecast

  • Rainfall in mid-November may have initiated some low-density local breeding. Low density nymphs could develop during December and a small increase in adult densities is possible during January.
  • The distribution of rainfall will influence the likelihood of any further breeding during summer.
  • There is a low probability of significant immigration from other regions during summer.

Risks

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

Far West and Far Southwest
Western Local Land Services

Locusts and conditions

  • Previous surveys identified a widespread low density adult population in these regions. There were no reports of locust activity.
  • The population that developed in the area south of Broken Hill in October was monitored throughout November. Adult numbers remained at Numerous density and residual late instar nymphs were recorded until 23 November. It is likely that older adults dispersed within the region, while recruitment of fledging nymphs maintained the density of young adults. Sampled females showed no egg development. Adult numbers had declined to Scattered density in late November.
  • No surveys were conducted in the Far West region during November, but light trap data indicates redistribution of adults on multiple nights.
  • The White Cliffs light trap recorded 142 locusts on 7 November and further catches during 18–21 November. Low numbers were recorded at Fowlers Gap on several nights during November and 50 on 22 November.
  • There was light rainfall (<20 mm) in the Cobar, Tibooburra, Balranald–Wentworth and Ivanhoe districts during 8–15 November, with some localised heavy falls. The Ivanhoe area recorded 50 mm on 12 November. There was further light rainfall in the Wentworth–Balranald district during 22-28 November. Ephemeral pasture vegetation has dried off in most areas, but soil moisture levels have maintained perennial grass growth in some habitat areas.

Forecast

  • Heavy rainfall in the Ivanhoe–Pooncarie area on 12 November could have initiated breeding and some localised egg laying was likely in the following week. Further rains on 23 November could have expanded the area of potential egg laying. Nymphs are likely to develop in the Ivanhoe and Wentworth-Balranald districts during December. Most will be at low-medium densities, but Bands could develop in localised areas. Fledging of nymphs will follow in January. An increase in adult densities is likely, but dry conditions could result in increased nymph mortality.
  • Sporadic low density egg laying was possible in residual green habitat areas of the Far West region and in response to storm rainfall during November, particularly in the Tibooburra or Broken Hill districts. Low density nymphs at various development stages may be detected during December.
  • There is a low probability of further breeding without moderate–heavy rainfall during December.
  • There is a low probability of immigration from other regions during December or January.

Risks

  • There is a moderate risk of localised high density nymphs developing in part of the Far Southwest region during December, but a low risk of widespread regional infestations during 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

  • The October nymph generation fledged during November, contributing to regional adult densities. Adult numbers remained at medium densities in southern Diamantina and Barcoo Shires in late November as a result of natural mortality, redistribution and migrations.
  • Surveys in Quilpie and the Thargomindah area of Bulloo Shire in early November identified Isolated–Scattered density adults in most areas. No nymphs were detected.
  • Surveys in Barcoo and Diamantina Shires at the end of November identified Scattered–Numerous density adults in the Birdsville–Betoota and Arrabury areas. Residual Present density late instar nymphs were detected at several locations.
  • There was localised light rainfall (<20 mm) in southern Barcoo and Bulloo Shires during 8–15 November. Vegetation in most locust habitat areas continued to dry out during November.

Forecast

  • There may have been sporadic egg laying in residual suitable habitats during November, which would produce mostly low density nymphs during December. A range of development stages is likely to be present as any egg laying was not synchronised by rainfall.
  • In the absence of heavy rainfall during December or January, habitat conditions will become unsuitable for further locust breeding. The population level will gradually decline in dry conditions during summer. However, single heavy storm rainfall events could initiate localised breeding that would produce a summer nymph generation.
  • There is a low probability of immigration to this region or significant emigration to adjacent regions during December or January.

Risks

  • There is low risk of a widespread regional infestation developing during 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 generally low in surveyed areas during November.
  • Surveys of Longreach and Blackall-Tambo Regional Council (RC) areas in early November identified Isolated–Scattered density adults in most areas. Present density mid- and late instar nymphs were detected at several locations.
  • There was localised light–moderate storm rainfall (<20–40 mm) in the northern shires of the Central West and Northwest regions during the first half of November. The Tambo–Augathella area received patchy light–moderate rainfall at that time and further light–moderate falls during 23-30 November. Pasture vegetation became dry in most areas during November.

Forecast

  • Locust population levels are expected to remain generally low in these regions during December. Drying vegetation will limit breeding opportunities in most of the region, but summer storm rainfall could provide opportunities localised egg laying.
  • Moderate rainfall in the Blackall-Tambo RC area during November could have initiated sporadic egg laying, which would result in low density–medium nymphs developing in some locations during December.
  • There is a low probability of significant immigration during December or January.

Risks

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

Central Highlands
Central Highlands and Isaac Regional Council

Locusts and conditions

  • Locust population level is expected to have remained low during November.
  • No surveys were conducted and there were no reports of locust activity.
  • There was localised moderate–heavy storm rainfall (20->40 mm) in the Clermont and Alpha areas during the first week of November. There was further light–moderate (<20–40 mm) in the southern Central Highlands during 22-28 November. Pasture vegetation was generally dry during November.

Forecast

  • Any local breeding is only likely to maintain the low overall regional population density
  • 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.

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

Locusts and conditions

  • Locust population levels remained generally low in surveyed areas during November.
  • Surveys of the Murweh and Paroo Shires in early November identified Isolated–Scattered density adults in the Cunnamulla and Wyandra areas, and only occasional adults in Balonne Shire and the Maranoa Regional Council (RC) area.   Present density late-instar nymphs were recorded at one location south of St George.
  • There was widespread light rainfall (<20 mm) across the region during mid-November. There was localised moderate–heavy rainfall (20->40 mm) in part of the Western Downs RC area during the last week of November.

Forecast

  • Heavy rains in the Dalby district in late November could initiate some local breeding, which would produce nymphs in mid-December. Given the low known regional population level, this would likely result in low density nymphs that would fledge in late January.
  • There is a low probability of significant immigration from other regions during summer.

Risks

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

  • Surveys of the Far North and Northwest regions identified Scattered–Numerous density adults in the Coober Pedy–Marla–Arkaringa, Dulkaninna–Murnpeowie and Parachilna–Leigh Creek areas. Lower densities were recorded in other parts of these regions and in surveyed areas of the Northeast region. Numerous density late instar nymphs were recorded at one location near Barratta in the Northeast region. The adult populations in the Far North and Northwest regions are likely to have developed from spring breeding, following heavy rainfall in September.
  • The Dulkaninna light trap did not record any locusts during November.
  • There was light rainfall (<20 mm) in parts of the Northwest region in mid-November. Vegetation is now dry in most areas, with some residual localised green areas.

Forecast

  • Nymphs in the Northeast region and the northern Eyre Peninsula will have fledged during November, but are unlikely to contribute to a large in increase in adult population level.
  • Breeding and sporadic egg laying during November could produce localised, low density nymphs during December in residual green habitats of the Far North or Northwest regions.
  • There is a low probability of significant migrations within South Australia, or from adjacent regions in other states.

Risks

  • There is a low risk of widespread regional infestations developing in December or January.

Murray Valley, Mt Lofty Ranges & Southeast Region

Locusts and conditions

  • Locust densities are expected to have remained low. No surveys were conducted and there have been no reports. Fledging of any local spring nymphs did not result in any apparent increase in adult numbers.
  • There was light–moderate rainfall (<20-40 mm) in the Murray Valley and Southeast region in mid-November. Pasture vegetation was dry in most areas during November.

Forecast

  • Given the current low population level, any local breeding during December is unlikely to result in an increase in overall population.
  • There is low probability of any significant immigration during summer.

Risks

  • There is a low risk of a widespread infestation developing during 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 during November. No APLC surveys were conducted and there were no reports of locust activity.
  • Fledging of any spring nymphs would have occurred during November, but the absence of reports suggests there has been no significant adult population increase.
  • There was light–­moderate rainfall (<20–40 mm) in North Central and Northwest Victoria in mid-November, and further light rainfall in the North Central region during the last week of the month. Pasture vegetation is becoming dry in most areas.

Forecast

  • Adult population is likely to have risen to Scattered density in some areas as a result of fledging of spring generation nymphs. There is a low probability of a large population increase during summer.
  • Sporadic low density breeding of spring generation adults is possible during December, but only low density nymphs are likely to develop in January.
  • There is a low probability of significant immigration from New South Wales during December or January.

Risks

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

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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