Locust Bulletin January 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 and maps of locust distributions. 

Table of Contents



General situation in December and outlook to March 2016

Australian Plague Locust
Spur–throated Locust
Migratory Locust

Australian plague locust
Chortoicetes terminifera

The locust population remained at low densities in most regions during December. High numbers persisted in eastern areas of Central West New South Wales, with several reports of swarms from areas to the east of Dubbo. Surveys identified low density adults in South Australia, Northwest and Central West New South Wales and Central West Queensland. Medium density adults were only recorded in localised areas of Central West Queensland and Central West New South Wales and very few nymphs were detected, despite heavy rainfall in some areas during November. Habitats were too dry and population levels too low for significant breeding in most regions during December, but moderate rainfall in Central West Queensland, Northwest, Far West and Central West New South Wales, and in the Far North region of South Australia in mid-December could have initiated some localised egg laying. However, the widespread heavy rainfall in northern South Australia and in Queensland at the start of January will produce favourable conditions for egg laying and nymph survival.

Swarm activity continued in the eastern part of Central West New South Wales and there were several reports from the Coonabarabran–Coolah–Dunedoo–Gilgandra area. Some unreported swarm egg laying is likely to have occurred in this region after mid-December. Surveys recorded consistent low density adults in the Central West, Northwest and Riverina regions, with some medium density adults in the Nyngan¬–Tullamore area.

Surveys in Central West and South Central Queensland identified consistent low density adults in most areas, with medium density adults only in the Tambo area. Heavy rainfall at the start of January in Southwest, Central West, Northwest, South Central and the Darling Downs regions will produce favourable habitat conditions for locust breeding during January.

Adult numbers remained low in surveyed areas of South Australia during December. There were consistent low density adults in the Burra–Port Augusta–Hawker area of the Northeast region, but only occasional adults were identified on the western and eastern sides of the North Flinders Ranges in the Far North region. Heavy rainfall in the Far North at the start of January will produce favourable habitat for locust breeding and nymph developmentl in areas around Lake Eyre throughout January.

The locust population remained low in northern Victoria. Reports from areas north of Melbourne in December were identified as mixed other grasshopper species.

The rainfall in northern South Australia and Queensland at the start of January has altered the outlook for a potential population increase in February and March. Favourable habitat conditions in several regions will allow repeated egg laying in some areas during January, but the current low population level in those regions may limit the scale of high density egg laying and of subsequent nymph populations in late January and February. In New South Wales, continued favourable habitat conditions in the eastern parts of the Central West and Northwest Plains regions are likely to allow nymphs to develop in localised areas during January. However, reports indicated a decline in adult numbers during December and no egg laying was reported, so a summer generation population is likely to be smaller than that during spring. The current El Niño in the tropical Pacific Ocean indicates dry conditions should persist during summer in southeast Australia. There is a moderate risk of population increases and localised infestations developing in several regions in February. There is a low risk of widespread infestations affecting agricultural regions of several states during autumn.

5 January 2016

Spur-throated locust
Austracris guttulosa

There is a widespread low density adult population in the Central West and Central Highlands regions of Queensland. Isolated–Scattered and some Numerous density adults were recorded in the Longreach, Barcaldine and Blackall-Tambo Regional Council areas of the Central West in mid-December. Surveys in November identified similar densities in the Central Highlands region, Isolated–Scattered density adults in South Central and Northwest Queensland and only occasional adults in Southwest Queensland, in Far West New South Wales and in Far North South Australia.

Adults often migrate at the start of the northern wet season and further population redistributions may contribute to local increases in summer breeding populations in Southwest, South Central and Northwest Queensland, and far North South Australia. Breeding is likely to have commenced in November in the Central Highlands, Central West, South Central and the Queensland Gulf regions, but no nymphs were detected in the Central West in December. Rainfall during December would have allowed localised egg laying to continue in the Central West, Central Highlands and Gulf regions, but the widespread heavy rainfall at the start of January will expand favourable habitat conditions in these regions, as well as in the Southwest and South Central regions. This will enhance the survival of nymphs and allow widespread egg laying to continue during January. Females usually disperse to lay eggs and can lay several pods of eggs during summer.

Nymphs of this species usually do not aggregate to form bands, but can reach densities >30 m2 in favourable habitats. Nymph numbers are likely to increase in Queensland during February and March. Any egg laying in northern New South Wales or South Australia is likely to produce only low density nymphs. Fledging of early nymphs commences in February and continues during autumn. Adult numbers will increase again during autumn.

The heavy rains at the start of January have altered the outlook for an overall increase in population during autumn to a higher level than in previous years. Survival of nymphs hatching from eggs laid in January will be influenced in some areas by any further rainfall in February. There is a moderate risk of localised swarm formation during autumn 2016, particularly in the Central Highlands and Central West Queensland.

Migratory locust
Locusta migratoria

Low density adults were identified in eastern areas of Central West Queensland during December. Surveys in November recorded Isolated and Scattered density adults from the Springsure-Taroom area in the Central Highlands and Numerous density adults near Alpha in Barcaldine Regional Council (RC) area. Heavy rainfall at the start of January will create widespread favourable habitat for further breeding in the Central Highlands, Central West and South Central regions. This species is capable of continuous breeding during summer and autumn, resulting in populations comprising all life stages. Successful breeding in January would produce nymphs in February, but there is insufficient information on current population level to assign an infestation risk.

There is a moderate probability of small gregarious populations developing in parts of the Central Highlands, Isaac, Barcaldine or Maranoa RC areas, in Murweh or Banana Shire during summer. Gregarisation often occurs at local scales and is often associated with summer cropping. Landholders are encouraged to report any locust activities.

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 L​ocust Commission.

back to top

Australian plague locust distribution 1 December to 31 December 2015

Local Distribution Map

back to top

Situation in December and forecast to March 2016

New South Wales

Central West and Northwest Plains

Central West, Northwest and Central Tablelands Local Land Services

Locusts and conditions

  • Landholders reported locusts in Central West, eastern Northwest and northern Central Tablelands Local Land Services (LLS) areas during the first half of December. There were reports of Numerous density adults and several swarms from the area bounded by Coonabarabran–Coolah–Dunedoo–Mendooran in Central West LLS, and from near Croppa Creek in the Northwest LLS. Several reports included locust nymphs and various mixed other species. There were fewer reports during the second half of December, suggesting a gradual decline in adult numbers.
  • Surveys in the Narromine, Nyngan and Coonamble districts in early December identified Scattered density adults in most areas, along with Numerous density adults in the Trangie–Tottenham area. Present density mid-instar nymphs were detected at one location near Nymagee.
  • Surveys in the Walgett, Moree and Warialda districts of Northwest LLS in mid-December identified Isolated and some Scattered density adults. No nymphs were detected.
  • Eastern districts of the Northwest LLS received light-moderate (20–40 mm) rainfall during each week of December, with localised heavy falls in the Moree, Narrabri and Warialda districts in mid-December. There were also light–moderate falls in the eastern Central West and Northern Tablelands LSS areas. There was further light–moderate rainfall in the Central West, Northwest and Central Tablelands LLS areas in late December. Pasture vegetation remains green in eastern areas of the region.

Forecast

  • Some localised swarm egg laying is likely to have occurred in mid-December in areas east of Dubbo in Central West LLS. This was most likely in the Coonabarabran–Mendooran–Coolah–Binnaway area, although no egg laying has been reported. Eggs laid in the second half of December will hatch from early January, but the population level of nymphs from a second generation is likely to be much smaller than the spring generation due to landholder control efforts and increased parasitism. Medium density nymphs could also develop in the southern and eastern parts of the Central West during January, with the possibility of Bands in some locations.
  • Adult numbers will continue to decline during January, but there is a moderate probability of a further increase during February if there is a high survival rate of second generation nymphs. There is a low probability of widespread swarm formation in the Central West LLS during February.
  • Localised heavy rainfall in the Moree and Warialda districts could have initiated some egg laying in mid-December, and localised nymphs could develop during January to fledge in February. An increase in adult numbers is likely during February, but there is a low probability of widespread swarm formation in Northwest LLS area.
  • Heavy rainfall during January will influence the likelihood and location of aggregation of adults and further swarm egg laying.
  • The adult population level will continue to decline continue during January. Further population increases are dependent on the success of second generation nymphs.
  • There is a low probability of significant immigration from other regions during summer.

Risks

  • There is moderate risk of localised second generation nymphs developing in eastern parts of the Central West and Northwest regions during January, but on a smaller scale than the spring generation.

Riverina

Riverina and Murray Local Land Services

Locusts and conditions

  • Surveys in mid-December indicated a low density adult population. Isolated–Scattered density adults were recorded in the Hay, Deniliquin and Balranald districts.
  • There was patchy light-moderate storm rainfall (<20­–40 mm) in the Hillston, Hay and Wagga districts in mid-December, and further light falls (<20 mm) in the Corowa and Wagga districts at the end of the month, but pasture vegetation remains dry in most areas.

Forecast

  • Given the low numbers of adults recorded in the region and current dry habitat conditions, any breeding during summer is likely only to result in the maintenance of an overall low density population.
  • There is a low probability of any significant immigration from other regions during summer.

Risks

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

Far West and Far Southwest

Western Local Land Services

Locusts and conditions

  • Population densities are likely to have remained low during December, given the low numbers identified previously and the very dry habitat. Limited surveys in the Cobar district in early December identified isolated–Scattered density adults, but no locusts were detected in the Broken Hill–Cockburn area.
  • The White Cliffs light trap recorded low numbers of locusts on 10 December. The Fowlers Gap light trap recorded 25 locusts on 30 and 5 on 31 December.
  • There was patchy light-moderate rainfall (20–40 mm) in the Broken Hill, Wilcannia, White Cliffs, Ivanhoe and Cobar districts during 20–27 December. Vegetation remains dry in most areas, with some localised green areas reported around Fowlers Gap.

Forecast

  • The rainfall in mid-December produced suitable habitat for some localised breeding. However, the low regional adult population level is likely to produce mostly low density nymphs in January and survival will be limited as vegetation becomes dry.
  • Previous undetected breeding was possible in the Bourke or Brewarrina districts and could have produced an adult population which redistributed in late December. At this stage egg laying in this region in January is likely to be at low densities in limited areas.
  • There is a low probability of significant immigration from other regions during January or February, but this will increase during March, depending on population developments in Queensland and northern South Australia..

Risks

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

back to top

Queensland

Southwest

Barcoo, Bulloo, Quilpie & Diamantina Shire

Locusts and conditions

  • Population density is expected to have remained very low in this region during December. No survey was conducted and there were no reports of locust activity.
  • There was light rainfall (<20 mm) in parts of Diamantina Shire during mid-December. Pasture vegetation remained dry in most of the region, but widespread heavy storm rainfall (>40 mm) in parts of all Shires at the start of January will produce a vegetation response in areas of Barcoo, Quilpie and Bulloo Shires throughout the month.

Forecast

  • Population levels will remain generally low during January, but favourable habitat conditions for breeding are likely to result in aggregation of adults and some localised high density egg laying during the first half of the month.
  • Migratory redistribution and some immigration from other regions is likely to contribute to an increase in January breeding population densities repeated egg laying is likely to occur in areas that received heavy rainfall and associated flood-out areas.
  • Hatching will occur after mid-January, and most nymphs will fledge in late February. However, given the low background population levels in this and adjacent regions prior to January, high density nymphs and Bands are only likely to develop in localised areas and a widespread regional infestation remains unlikely.
  • An increase in adult population is likely in February and March, but widespread swarm formation is unlikely.

Risks

  • There is a moderate risk of localised population increases during February and March.

Central West & Northwest

Longreach, Barcaldine and Blackall - Tambo Regional Shire. Boulia, Cloncurry, Flinders, Mckinlay, Mt Isa, Richmond and Winton Shire

Locusts and conditions

  • Locust population levels remained generally low in surveyed areas during December. Surveys in the Longreach, Barcaldine and Blackall-Tambo Regional Council (RC) areas in mid-December identified consistent Isolated–Scattered density adults in many areas, along with Numerous density adults along the Ward River south of Tambo. No nymphs were detected.
  • There was patchy light–moderate rainfall (<20-40 mm) in Boulia Shire during the first week of December. There was heavy (>40 mm) storm rainfall in Winton, Boulia and northern Shires during the second half of December. In the Central West there was light–moderate rainfall (<20-40 mm) in mid-December, followed by widespread heavy storms (>40 mm) at the start of January. Pasture response may be limited in areas that have been seriously drought affected.

Forecast

  • Habitat conditions were favourable for localised locust breeding in the Barcaldine and Blackall-Tambo RC areas during December, and widespread heavy rainfall at the start of January will maintain green habitat throughout the month. Although no nymphs were detected during December, there is likely to be an adult population which could aggregate and lay eggs at high densities in some locations during the first half of January. Redistribution of adults could also result in some high density egg laying in parts of Longreach RC area or Winton Shire that received heavy rainfall at the start of January.
  • Eggs laid in early January will hatch after the middle of the month and surviving nymphs will fledge in the second half of February. Localised high density nymphs could develop Bands in some areas in February. However, there may have been some earlier egg laying in parts of the Blackall-Tambo RC area during December, and there could be some increase in adult numbers during 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 during summer, but high density nymphs could develop in localised areas.

Central Highlands

Central Highlands and Isaac Regional Council

Locusts and conditions

  • Locust densities are likely to have remained low during December. No surveys were conducted and there were no reports of locust activity.
  • There was patchy moderate–heavy storm rainfall (20–>40 mm) in the Central Highlands Regional Council (RC) area in early December and further moderate–heavy falls throughout the region in the last week of the month.

Forecast

  • Habitat conditions are favourable for locust breeding in Central Highlands RC area during January and there could have been some earlier localised egg laying in December. This would have maintained the overall low density regional population levels, but some aggregation and higher density breeding could increase population densities during January or February.
  • There is insufficient information on current life stages and densities to forecast likely development times.
  • There is a low probability of any significant 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 densities are likely to have remained low in most areas during December. Limited survey in Murweh Shire identified Isolated–Scattered density adults in the Augathella–Charleville area.
  • Parts of Maranoa and Western Downs RC areas received light–moderate (<20–40 mm) storm rainfall during the first and second weeks of December. There was further patchy moderate–heavy (20–>40 mm) rainfall in these areas and in Murweh Shire during the last week of the month.

Forecast

  • Rainfall continued to produce suitable habitat conditions for locust breeding in parts of Maranoa and Western Downs RC areas, and in northern Murweh Shire. However, storm rain totals have been highly variable and opportunities for egg laying have been mixed. There is insufficient information on current life stages and densities to forecast likely development times and locations, but the heavy rainfall at the start of January may synchronise further breeding and produce an identifiable nymph cohort in late January. Fledging would follow in late February and result in a moderate increase in adult densities.
  • There is a moderate probability of a regional population increase in February, but widespread swarm formation is unlikely.
  • There is a low probability of significant immigration from other regions during summer.

Risks

  • There is a low risk of a widespread regional infestation 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.

back to top

South Australia

Far North, Northeast, Northwest & Western Agricultural Region

Locusts and conditions

  • Locust densities were generally low in surveyed areas during December.
  • Surveys in the Northeast region in mid-December detected a small population increase, with Isolated–Scattered density adults at numerous locations in the Burra–Quorn–Orroroo-Hawker area. Only occasional adults were recorded on the eastern and western sides of the North Flinders Ranges, and in the Yunta–Olary area. No nymphs were detected during surveys.
  • The Oodnadatta and Dulkaninna light traps recorded no locusts during December.
  • There was light–moderate rainfall (20–40 mm) in parts of the Northwest and Far North regions during 15-22 December, and some locally heavy falls (>40 mm) in the Nar North. There was further heavy rainfall in areas around Lake Eyre in the Far North at the start of January.

Forecast

  • Survey results suggest a very low population level in the Far North, so that any breeding following mid-December rainfall would only have been at low densities. However, the heavy rainfall at the start of January will ensure the survival of any nymphs and allow further adult egg laying during January.
  • If some egg laying occurred after rain during December, hatching could commence before mid-January. Eggs laid in early January would hatch from 20 January. The known population level in northern South Australia and adjacent regions in other states was very low, so redistribution and migration is unlikely to result in swarm egg laying.  Some high density nymphs could develop in restricted areas of favourable habitat in February, but are unlikely to result in widespread swarm formation.
  • There is a low probability of any significant immigration from other states during summer.
  • There is a low probability of migrations between South Australian regions during January, but some redistribution is possible in late February and March if there is successful breeding in the Far North.

Risks

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

Murray Valley, Mt Lofty Ranges & Southeast Region

Locusts and conditions

  • The locust population is expected to have remained at a low level during December.
  • There was no significant rainfall during December and pasture vegetation is mostly dry.

Forecast

  • There is a low probability of any high density breeding or a large population increase during summer.
  • There is a 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.

back to top

Victoria

North West & North Central Victoria

Locusts and conditions

  • Locusts remained at low densities in Victoria during December.
  • There were continued reports from areas north of Melbourne during December, a number of which were identified as mixed grasshopper species.
  • There was localised light–moderate rainfall (20–40mm) in the eastern part of North Central Victoria in mid-December. Natural pastures are dry in other parts of the state.

Forecast

  • The locust population is expected to remain at low density during summer, given its current low level and dry vegetation conditions.
  • There is a low probability of immigration into Victoria during summer.

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.

back to top

Glossary of locust terms and density categories used in the Locust Bulletin

Locust biology and behaviour

TermDefinition
adultA winged locust
bandDense aggregation of nymphs, usually moving forward together
diapausePeriod of developmental suspension in response to predictable and 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
nymphImmature wingless locust. Often referred to as the hopper stage
swarmDense aggregation of flying adults, milling at the same spot or moving en masse

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)
Victoria

Biosecurity 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

back to top​​​​

​​​ ​​​​​​​​​​​

​Other format