Locust Bulletin February 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 January and outlook to April 2017

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Australian plague locust - Chortoicetes terminifera

Locust populations remained at medium densities in many regions during January. However, reports at the end of the month indicated a large increase in adult numbers in parts of the Far North and Northwest regions of South Australia. These developed from breeding that started in mid-December in those regions. Mid-instar nymphs were identified at several locations in Far West New South Wales during January, indicative of the development stages of the nymph cohort in northern South Australia. The expected scale of January populations in Southwest and Central West Queensland was not detected by surveys, which identified mostly low density adults and occasional nymphs. The fledging of the December nymphs in Central West New South Wales produced only a small increase in the regional population level and no swarms were reported in the Trangie–Dubbo area, where there had been small bands. Heavy rainfall in northern South Australia and Southwest Queensland in late January has produced favourable habitat for further locust breeding and nymph survival. An autumn generation of nymphs could develop in February and March.

In Central West New South Wales, low density nymphs were identified in the Trangie–Albert area in early January and a small swarm of fledgling adults was recorded near Narromine. Adult numbers subsequently increased to medium densities in parts of the region. Surveys in the Broken Hill–Tibooburra area of the Far West region recorded medium density adults and low–medium density nymphs at numerous locations. Adult numbers increased to medium densities in the Bourke–Brewarrina area in the second half of January, and a single swarm was identified near Bourke. Population levels are expected to have remained low in the Far Southwest and Riverina regions.

In Queensland, mostly low density adults and occasional late instar nymphs were recorded in the Southwest, Central West and South Central regions during January. Medium density adults were identified in parts of Barcoo and Bulloo Shires. Habitat conditions in several regions remain favourable for localised breeding.

In South Australia, flying locusts were reported from the Coober Pedy–Oodnadatta area in late January. Initial surveys confirmed a widespread medium density population of young adults and mid-instar nymphs in the Northwest region. High numbers of locusts were also reported from the Murnpeowie–Moolawatana area of the North Flinders Ranges.

Population levels are expected to have remained low in Victoria. No surveys were conducted and there have been no reports.

The outlook is for increasing adult numbers and further swarm activity in northern South Australia during February after the fledging of nymphs from eggs laid in late December. There is also potential for another significant nymph generation in northern South Australia, and possibly in Southwest Queensland, in late February and March if swarms lay in habitats made favourable by the heavy rainfall at the end of January. There is a moderate risk of some movements to other regions of South Australia or into NSW during February and the likelihood of southward migrations will increase during autumn. Populations are likely to remain at low–medium densities in most other regions during February, although increased adult numbers are possible in Far West NSW.  Medium density populations could establish in southern South Australia and NSW, and possibly northern Victoria during autumn, depending on migrations, but there is a low probability of widespread swarm infestations affecting agricultural regions in several states.

6 February 2017

Spur-throated locust - Austracris guttulosa

There is a widespread medium density population throughout inland Queensland. Surveys over recent months have identified Scattered-Numerous density adults in the Central West, Northwest and Central Highlands, and parts of Southwest and South Central Queensland. Low density nymphs were identified at many locations in the Central West and northern parts of the South Central region during January. The increase in nymph records reflects more widespread egg laying following heavy rainfall in December.

Surveys in January identified consistent Scattered–Numerous density adults in the Longreach, Barcaldine and Blackall-Tambo Regional Council (RC) areas. Present density nymphs at a range of developmental stages were detected throughout Central West Queensland. Scattered–Numerous density adults and occasional nymphs were also recorded in Quilpie, Paroo and Murweh Shires. Isolated–Scattered density adults were recorded elsewhere in Southwest and South Central Queensland, and also in the Far West, Northwest Plains and Central West regions of NSW.

Heavy rainfall in several regions of Queensland during January will allow breeding to continue. Females can lay several pods over the course of summer. Egg development to hatching in this species takes 3–4 weeks and nymph development a further 8–10 weeks. Further nymphs are likely to develop during March and April. Fledging of nymphs hatched in previous months will start in February and the numbers of young adults will increase during autumn. These will largely replace the previous generation as it dies out, although some swarms are likely to form in late autumn. There is a low risk of a large increase in overall population level during 2016–17.

Migratory locust - Locusta migratoria

The Queensland Central Highlands region was not surveyed during January and this species was not detected in other regions. However, surveys over recent months identified low numbers of adults in the southern Central Highlands.

Rapid population increases can occur in the Central Highlands, eastern Central West and South Central regions of Queensland. Rainfall during January will produce favourable habitat conditions for continued breeding during the remainder of summer. Small gregarious populations could develop in localised areas of the Central Highlands, but there is a low probability of widespread gregarious populations developing during February or autumn.

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

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Australian plague locust distribution 1 January to 3 February 2017

Map of Australian plague locust distribution 1 January to 3 February 2017

 

Australian plague locust (Chortoicetes terminifera)

Situation in January and forecast to April 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

  • Nymphs in the Trangie–Dubbo area of the Central West fledged in early January, but there has been only a moderate increase in regional adult population levels.
  • Surveys in early January detected only low density adults and late-instar nymphs in the Trangie–Albert and Narromine–Mungery areas. In mid-January a single small area of Concentration density fledgling adults and Sub-band density late instar nymphs was identified southwest of Narromine. There were no further reports of locust activity from the area. Only Isolated–Scattered density adults were recorded in northern Central West Local Land Services (LLS) region.
  • Limited survey of part of Northwest LLS area in mid-January identified Isolated–Scattered density adults in the Burren Junction and Mungindi areas.
  • Surveys of the Bobadah–Condobolin–Forbes area in late January identified Scattered–Numerous density adults.
  • There was patchy moderate-heavy rainfall (20–>40 mm) in eastern parts of the Northwest LLS and light–moderate falls (<20–40 mm) in the northern Central West LLS during the third and fourth weeks of January. Pasture vegetation is drying off in many areas.

Forecast

  • Young adults are likely to have redistributed to areas that received moderate rainfall during January. There may have been sporadic egg laying during the second half of January localised nymphs could develop during February. Nymphs would start fledging in late February, but are unlikely to cause a large increase in adult numbers.
  • The regional adult population is likely to remain at low densities during February and March.
  • There is a low probability of significant immigration from other regions during February, but the probability will increase in March and April.

Risks

  • There is a low risk of widespread infestations developing during February and March.

Riverina
Riverina and Murray Local Land Services

Locusts and conditions

  • The locust population is expected to have remained at a low level during January, given the very low numbers recorded in December and dry habitat in most areas.
  • There was patchy light rainfall (<20 mm) in the southern part of Murray LLS during the last week of January. Pasture vegetation is becoming dry in most areas.

Forecast

  • Any local breeding after rains in eastern districts of the region in December is only likely to maintain the low regional population density during February.
  • There is a low probability of significant immigration from other regions during February. The likelihood of immigration will increase in March and April if adult populations increase in western regions of NSW.

Risks

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

Far West and Far Southwest
Western Local Land Services

Locusts and conditions

  • Nymphs developed in the Broken Hill–Tibooburra–White Cliffs area of the Far West region during January after widespread rainfall in mid-December. An increase in adult numbers was recorded in the Bourke district in late January.
  • Adult locust activity and transient high numbers were reported from areas north of Broken Hill at the start of January, as evidenced by peak light trap catches at Fowlers Gap and White Cliffs. This occurred during the passage of a low pressure weather system and numbers reportedly declined in the following week. Subsequent surveys identified Scattered–Numerous density adults.
  • Surveys on 10 January identified Present–Numerous density mid-instar nymphs at a number of locations in the Broken Hill–Fowlers Gap area. Surveys during 17–21 January identified early and mid-instar nymphs in the Cobham, White Cliffs and Tibooburra areas. Nymph stages indicate egg laying commenced after the heavy rains in mid-December and continued for several weeks. There were Isolated–Scattered density adults in the Tibooburra, White Cliffs and Wanaaring districts.
  • Survey of the Bourke, Brewarrina and Goodooga districts in mid-January identified only Isolated–Scattered adults. Subsequent surveys in late January recorded Numerous density adults in the Bourke–Brewarrina–Louth area and high density adults were concentrated along the roadside north of Bourke. Samples showed half of the females were developing eggs. The increase in numbers is likely the result of redistribution and aggregation of the regional population.
  • No surveys were conducted in the Far Southwest region during January.
  • The Fowlers Gap and White Cliffs light traps recorded only low numbers of locusts during January, after very high numbers at the end of December.
  • There was patchy light rainfall (<20 mm) across the Far West region and Broken Hill–Wentworth district, along with localised moderate (<20-40 mm) falls in the Wanaaring district, during 15–21 January. There was further localised light–moderate falls in the Tibooburra district during the last week of January. Pasture vegetation is becoming dry in some habitat areas.

Forecast

  • Nymphs in the Broken Hill–Fowlers Gap, Milparinka and Tibooburra areas will have started fledging in late January and this will continue during the first half of February. The detected nymphs were possibly part of a more widespread population in those areas, but the extreme high temperatures may have caused increased mortality. Adult numbers will increase during early February. Some localised swarm formation is possible, but locusts are likely to disperse within the region.
  • The probability of small migrations from the Far West to other regions in New South Wales, and of immigration from northern South Australia will increase during March and April.

Risks

  • There is a low risk of widespread regional infestations developing during February 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 adult population remained at medium densities in surveyed areas during January. A sequence of heavy rainfall events has maintained favourable habitat conditions for locust breeding.
  • Surveys at the start of January identified consistent Scattered–Numerous density adults in Bulloo Shire and Isolated–Scattered densities in Quilpie, Barcoo and southern Diamantina Shires.
  • Surveys in Bulloo Shires in mid-January identified Isolated–Scattered density adults in most areas, with Numerous density in the Noccundra area. Surveys in Diamantina and Barcoo Shires identified Scattered–Numerous density adults in the Arrabury–Betoota–Morney area. No nymphs were detected during survey.
  • The Birdsville light trap recorded locusts on several days during the first week of January, with over 200 on 5 January. No locusts were recorded at the Nooyeah Downs light trap.
  • There was moderate rainfall (20–40 mm) in Barcoo and Quilpie Shires during 8–14 January. There were further moderate falls, and some heavy storms (>40 mm) in Bulloo and Quilpie Shires during 15–21 January. There was moderate–heavy rainfall (20->40 mm) in Diamantina, Barcoo and Quilpie Shires during 22–29 January. Vegetation is green in many locust habitat areas.

Forecast

  • Multiple rainfall events during January are likely to have initiated egg laying in some habitats. However, extreme daytime temperatures could have increased mortality of nymphs. Some hatchings are likely in early February in Quilpie and Bulloo Shires, and mid-February in Diamantina and Barcoo Shires. Bands could develop in localised areas. Fledging would follow from late February and a moderate increase in the adult population level is likely.
  • Despite few nymphs being detected by surveys during January, a further increase in adult numbers is possible during February after nymphs in other areas fledge. However, extreme high temperatures during January could have increased the mortality of nymphs.
  • There is a moderate probability of some immigration from adjacent regions during February, or migration from the region in March.

Risks

  • There is low risk from a nymph generation developing in late February and of localised swarm formation 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 remained at generally low levels in surveyed areas during January.
  • Limited surveys in the Central West in late January identified Isolated–Scattered density adults in Longreach and Blackall-Tambo Regional Council (RC) areas. Present density mid-instar nymphs were detected at one location near Blackall.
  • The Longreach light trap did not record locusts during January.
  • There was moderate–heavy storm rainfall (20->40 mm) in the northern shires of the Central West and Northwest regions throughout January. There was localised heavy rainfall in Barcaldine and Blackall-Tambo RC areas during 8–14 January, followed by widespread moderate–heavy falls, with some totals >100 mm, throughout the Central West and Northwest during 15–21 January. Further light–moderate storms fell in the Longreach, Winton and Boulia Shires during the last week of the month. Pasture vegetation will remain green in areas that received heavy rainfall.

Forecast

  • Locust population levels are expected to remain generally low in these regions during February and March.  Breeding by the local population is likely to produce low–medium density nymphs during February. However, the widespread heavy rainfall in the Central West in mid-January has produced favourable habitat conditions, which could have allowed repeated egg laying. The development of localised higher density nymphs is possible from mid-February.
  • There is a low probability of significant immigration during February or March.

Risks

  • There is a low risk of a widespread regional infestations developing during February or March.

Central Highlands
Central Highlands and Isaac Regional Council

Locusts and conditions

  • Locust population levels are expected to have remained generally low, but a moderate increase was possible in the southern Central Highlands Regional Council (RC) area.
  • APLC did not survey this region during January and there were no reports of locust activity.
  • Rainfall was dominated by tropical storms. There was light–moderate rainfall (<20-40 mm) in much of the region each week during January, with very heavy local storms up to 100 mm.

Forecast

  • Rainfall during January has provided favourable vegetation and soil conditions for locust breeding.  This would likely only maintain the low regional population density, but there is the potential for local population increases in the Arcadia Valley and Springsure areas.
  • There is a low probability of immigration from other regions during February or March.

Risks

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

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

Locusts and conditions

  • Surveys indicate locust population levels remained low during January.
  • Murweh, Paroo and Balonne Shires were surveyed in the second half of January. Isolated–Scattered density adults were identified in most areas and no nymphs were detected.
  • There was widespread light–moderate rainfall (<20-40 mm) during 14–21 January and further localised light–moderate falls during the last week of the month. Pastures remain generally dry in many areas.

Forecast

  • Any local breeding is likely to maintain the overall low regional population density. However, sporadic breeding could lead to moderate local population increases during February.
  • There is a low probability of significant immigration from other regions during February or March.

Risks

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

  • Heavy rainfall during the last two months, particularly in the Far North and Northwest regions, provided several opportunities for locust breeding and favourable habitat for nymph development. Reports of swarms at the end of January indicate fledging of a local nymph population that developed from eggs laid in mid-December.
  • Limited survey in the Innamincka area in mid-January identified Numerous density adults. Surveys of the northern regions were prevented by road closures.
  • Reports indicated a significant population increase in the Far North and Northwest regions. Swarm activity was reported from several locations in the Oodnadatta–Arkaringa­–Marla area, which occurred with a low pressure trough and convergent winds following heavy rainfall in the last week of January. Nymph Bands and high density adults were also reported from the Moolawatana–Murnpeowie area of the North Flinders Ranges.
  • Surveys of the Northwest at the start of February confirmed a widespread population of Numerous density adults and Present–Numerous density mid-instar nymphs in the Coober Pedy–Oodnadatta area.
  • The Dulkaninna light trap recorded low numbers of locusts in early January. The Oodnadatta light trap was not operational.
  • There was light–moderate rainfall (<20-40 mm) in the Western Agricultural region during 8–14 January, and in parts of the Northeast and Far North during 15–21 January. There was moderate–heavy rainfall (20->40 mm) in the Far North and Northwest during the last week of the month, with totals up to 100 mm in numerous locations. Pasture vegetation remains green in many habitat areas.

Forecast

  • Swarm activity is likely continue in the Far North and Northwest regions throughout February. Adult numbers will continue to increase after the fledging of nymphs from eggs laid at the end of December. The distribution of nymphs at similar development stages could be more widespread in the Far North region.
  • The current high density adults are mostly recently-fledged and will mature eggs rapidly during February. Redistribution and aggregation in green habitats is likely. Vegetation and soil conditions will remain favourable for swarm laying, which is possible from the second week of February. There is the potential for a further nymph generation during March. High density nymphs and Bands are likely to occur in drainage line and low-lying habitats.
  • Locusts currently in the Northwest region are unlikely to pose a direct migration threat to agricultural districts, as wind trends are predominantly to the west during February. However, some migration to the Western Agricultural region is possible. Nymphs still developing or yet to hatch in the Northwest and Far North regions will present an increasing risk of southward migrations during March and April.
  • There is a moderate probability of some migrations to other regions of South Australia or to western New South Wales during February and March. The likelihood of southward migrations will increase in autumn. If there is a further successful generation of nymphs during March, there will be a high risk of migrations during autumn.

Risks

  • There is a high probability of an increase in adult densities and swarm formation in the Far North and Northwest region during February. There is a moderate risk of a further nymph generation developing during March.
  • There is a moderate risk of migrations from the Far North region to the Northeast, Western Agricultural and Murray Valley regions during autumn.

Murray Valley, Mt Lofty Ranges & Southeast Region

Locusts and conditions

  • Locust densities are expected to have remained low during January. No surveys were conducted and there were no reports.
  • There was light–moderate rainfall (20-40 mm) in these regions during mid-January.

Forecast

  • Any local breeding during February is only likely to maintain the low regional population level.
  • The probability of some immigration will increase during March and April because of increased adult populations in regions to the north.

Risks

  • There is a low risk of a widespread infestation developing during February and March.
  • There is a moderate risk of some immigration from regions to the north during autumn.

Locust activity should be reported to Biosecurity SA (Primary Industries and Region South Australia) on the Locust Reporting Hotline on 1300 666 101. A toll-free call to the APLC can be made on 1800 635 962. An answering machine is attached for after-hours calls. Reports can also be e–mailed to APLC or sent through the web page at Australian Plague Locust Commission.

Victoria

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North West & North Central Victoria

Locusts and conditions

  • Locust population levels are expected to have remained low during January. There were no reports of locust activity.
  • There was light rainfall (<20 mm) in parts of North Central Victoria during 8–15 January and widespread light rainfall during 16–22 January. Pasture vegetation remains dry in most locust habitat areas.

Forecast

  • Any breeding of the local population during January is unlikely to result in a significant population increase.
  • The probability of some immigration from western New South Wales or South Australia will increase during autumn.

Risks

  • There is a low risk of a widespread infestation developing during February and 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
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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