Locust Bulletin December 2015

​​​​​​​​​​​​​​​​​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 November and outlook to February 2016

Australian Plague Locust
Spur–throated Locust
Migratory Locust

Australian plague locust
Chortoicetes terminifera

The locust infestation in Central West New South Wales continued during November, with nymphs and hopper bands reported in several areas. Fledging commenced in early November, with the bulk of fledging occurring in the eastern Central West in mid-November. As a consequence, adult locust numbers increased in Central West and Northwest New South Wales, with a number of swarms reported from areas east of Dubbo. Population levels remained low in other regions of New South Wales, Queensland and South Australia.  Rainfall in several regions of New South Wales, the Central West and Central Highlands of Queensland, and in southern South Australia in early November produced favourable habitat for locust breeding, but vegetation is drying out rapidly in some areas.

In Central West NSW, the majority of band reports were from the Coonabarabran–Coolah–Dunedoo–Gilgandra area. Smaller areas of nymphs and some bands were reported in the Gulgong–Mudgee, Nyngan–Tullamore and the Condobolin–Parkes–Tottenham areas. Fledging commenced in early November in the Narrabri and Nyngan districts and a few small swarms formed. The bulk of fledging occurred in mid-November in the Coonabarabran, Dubbo, Parkes and Condobolin districts. Swarms were reported in areas to the east and southwest of Dubbo in late November. Only low-density adults were observed in the Far West and Riverina regions, but medium densities were recorded in the Wilcannia and Ivanhoe districts of the Far Southwest.

Surveys in Queensland identified only low density adults in the Central West, Southwest, South Central and the Central Highlands regions. Heavy rainfall in the eastern Central West and Central Highlands regions in the first half of November produced favourable conditions for locust breeding. Adults from the spring generation identified in the Tambo area are likely to have laid eggs in some areas of Blackall-Tambo and Barcaldine Regional Council areas or northern Murweh Shire. Nymphs would appear in early December and could complete development at the end of the month.

Adult numbers are likely to have remained low throughout South Australia during November. Only occasional adults were detected in surveyed areas of the Northeast and Murray Valley regions. Medium density adults were recorded east of Burra. Heavy rainfall in the Burra–Port Augusta area and on the western side of the Flinders Ranges produced suitable conditions for locust breeding, and some sporadic low density egg laying was possible in mid-November. Drying conditions would restrict the development of any nymphs during December.

The population remained low in northern Victoria. Survey detected very few locusts in the Mallee district, but some adults were identified near Elmore in North Central Victoria in late November. Reports from near Seymour and Yea in late November were identified as mixed other grasshopper species.

The outlook is for localised swarm activity to continue in December in Central West New South Wales and for nymphs from a second generation to develop in parts of the Coonabarabran, Dubbo, Wellington, Narromine and Lachlan districts in December and January. Localised hopper bands are likely to develop in the eastern Central West. Nymphs could also develop in parts of the Blackall-Tambo, Barcaldine, Murweh or Maranoa Regional Council areas in Queensland during December, possibly with some bands. Population densities are expected to remain low in other regions during summer. The current strong El Niño in the Pacific Ocean indicates dry conditions should persist during summer in southeast Australia. Although single heavy rainfall events can result in successful locust breeding and population increases, there is a low risk of widespread infestations developing in other regions during summer.

3 December 2015

Spur-throated locust
Austracris guttulosa

There is a widespread medium density adult population in the Central West and Central Highlands regions of Queensland. Scattered and Numerous density adults were recorded throughout Longreach, Barcaldine, Isaac and Central Highlands Regional Council areas in mid-November. Following a report of high density adults from the Tarcombe–Bimerah area southwest of Longreach at the start of November, Numerous–Concentration density adults were identified at several locations along the Thompson River north of Tarcombe, extending west to Ban Ban, on 5 November. Subsequent survey in the same area on 11 November found adults numbers had declined to Isolated–Scattered densities. Landholders reported that locusts had migrated. Surveys during October recorded very low adult densities in Southwest, Northwest and South Central 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 population redistributions may contribute to local increases in summer breeding populations and the appearance of high densities or swarms. Given the very dry habitat in the Longreach area before November, the adults recorded around Tarcombe are likely to have been immigrants from the north and wind trajectories for 5 November suggest possible subsequent movement to the east and southeast. Occasional swarms may be also be detected in parts of the Central Highlands, Central West or Northwest regions in December, but are likely to disperse during summer breeding. The heavy rainfall in the Central Highlands, Central West, South Central and the Queensland Gulf regions in early November would have initiated breeding in some habitat areas. The first nymphs are likely to develop in December, but mortality is expected in areas that do not receive further rainfall during the month. Females can lay several pods of eggs during summer, and breeding is likely to continue. Egg laying periods are usually associated with rainfall.

The extent and duration of breeding during summer, and the survival of the resulting nymph generation will influence the overall population level for 2016. Fledging of early nymphs commences in February and continues during autumn. Adult numbers therefore increase again in late autumn. Any egg laying in northern New South Wales is likely to be at very low densities.

There is a low risk of widespread regional infestations during 2016, but a moderate probability of localised medium density nymphs developing in eastern and northern Queensland during summer.

Migratory locust
Locusta migratoria

Low density adults were identified in the Queensland Highlands and Central West regions during November. Surveys recorded Isolated and Scattered density adults from Springsure in the Central Highlands to Taroom in Banana Shire in mid-November. Numerous density adults were identified near Alpha, following heavy rainfall in eastern Barcaldine Regional Council (RC) area. Heavy rainfall recorded in the Central Highlands and northern Maranoa RC areas, and in Banana Shire, in late October and November produced suitable habitat for localised breeding. This would result in nymphs appearing from late November, with the possibility of bands developing in some locations. An increase in adult numbers in January would follow the fledging of nymphs.

There is a moderate probability of small gregarious populations developing in parts of the Central Highlands, Isaac, Barcaldine or Maranoa RC areas, or in Banana Shire, during summer. Gregarisation can occur 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 Locust Commission.

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News

Detailed rainfall information is available on the Bureau of Meteorology website.

Maps of previous locust distributions can be found in the Locust Bulletins and are available on the APLC webpage.

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Australian plague locust distribution 1 November to 30 November 2015

Local Distribution Map

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Situation in November and forecast to February 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 throughout November, and continued with ground control efforts. There were many reports of nymphs, hopper bands and fledglings confirmed by LLS staff. The main nymph infestation was in the area bounded by Coonabarabran–Coolah–Dunedoo–Gilgandra. Smaller areas of nymphs and some Bands developed in the Gulgong–Mudgee, Nyngan and the Condobolin–Tottenham districts. In the Northwest region, a few fledging Bands were reported in the Narrabri district in early November and nymphs were reported in the Gunnedah and Tamworth districts throughout the month.
  • Fledging of spring generation occurred at the end of October in the Narrabri–Moree and Nyngan districts. The bulk of fledging in areas east of Dubbo and the Tottenham–Condobolin area followed in mid-November. Numerous swarms were subsequently reported from the Coonabarabran, Mendooran, Binnaway, Coolah and Dunedoo areas, but most samples showed no egg development. Small swarms in the Trangie–Dandaloo–Trundle area showed egg development on 22 November.
  • Surveys in early November identified swarm density young adults in the Nyngan–Nymagee area and consistent Scattered–Numerous density adults in the Coonamble and Narrabri districts. In mid-November there were Scattered–Numerous density adults in the Warren–Trangie, Carinda–Quambone and Narromine–Peak Hill–Trundle-Condobolin areas.
  • Both regions received heavy rainfall (>40 mm) in early November. There was further light-moderate (20–40 mm) rainfall in the Central West, Central Tablelands and eastern parts of the Northwest region during 8-15 November. Pasture vegetation is green in eastern areas of these regions.

Forecast

  • Swarm activity will continue in areas east of Dubbo in the Central West LLS area during December. Sporadic swarm egg laying could occur in the Coonabarabran, Dubbo, Nyngan, Parkes, Tottenham and Condobolin districts in early December. This is most likely in the Coonabarabran–Mendooran–Coolah–Binnaway area. Eggs laid in early December would not hatch until after mid-month. Second generation nymphs will develop in the southern and eastern parts of the Central West in late December and January, with the likelihood of Bands in some locations.
  • Widespread heavy rainfall in early November produced favourable soil and pasture conditions for nymph development and adult reproduction. The bulk of the population was too young to have laid eggs before mid-November, but some localised laying was possible in the Northwest and northern Central West LLS areas. Localised hatchings would commence in early December.
  • The distribution of any storm rainfall during December will influence the likelihood and location of further swarm egg laying. Some mortality of nymphs is likely as vegetation conditions deteriorate in the absence of further rainfall.
  • Reports indicate redistribution of adults in the Central West, and further swarm movement could result in population fluctuations and localised increases in adult density.
  • The adult population level will peak in early December, after fledging from residual nymphs, and numbers should decline in January. Further population increases are dependent on the success of second generation nymphs.
  • There is a moderate probability of some migratory redistribution during December.

Risks

  • There is a high risk of continuing localised swarm activity in the eastern Central West LLS during December. There is moderate risk of a second high density nymph generation developing in some areas during December and January.

Riverina

Riverina and Murray Local Land Services

Locusts and conditions

  • Surveys in mid-November indicated a widespread low density adult population in the West Wyalong, Griffith, Hay, Deniliquin and Balranald districts. Isolated-Scattered density adults were identified in most areas and Present density mid-instar nymphs at one location near Deniliquin.
  • There was widespread heavy rainfall (>40 mm) during the first week of November and further patchy light–moderate (<20­–40 mm) falls in the eastern Riverina during the second week. Pasture vegetation responded during November.

Forecast

  • Given the low adult densities recorded in the region and the absence of nymphs during spring, the rainfall of early November is likely to have initiated only low density egg laying. Any eggs laid in mid-November would commence hatching in early December. Low–medium density nymphs could develop in localised areas during the month.
  • There is a moderate probability of some immigration from the Central West region during December.

Risks

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

Far West and Far Southwest

Western Local Land Services

Locusts and conditions

  • Population numbers remained very low in the Far West region during November, except in the Bourke and Brewarrina districts where Isolated–Scattered density adults were recorded. In the Far Southwest, surveys identified Isolated–Scattered density adults in the Broken Hill and Wilcannia districts, and Numerous density adults in the Ivanhoe–Mossgiel–Hillston area. Occasional late-instar nymphs were recorded in these areas. No locusts were detected in the White Cliffs or Wanaaring district.
  • The White Cliffs light trap recorded locusts in mid-November. None were recorded at Fowlers Gap.
  • There was widespread moderate rainfall (20–40 mm) during the first week of November, with some heavy falls in the Bourke and Brewarrina districts. There were patchy light–moderate (<20–40 mm) storm rains in parts of the Cobar and Ivanhoe districts during 8–15 November.

Forecast

  • Heavy rains produced suitable soil and vegetation conditions for breeding in the Bourke and Brewarrina districts during November. Rainfall would also have produced suitable conditions in localised areas of the Wilcannia and Ivanhoe districts. Given the generally low densities of adults recorded in those areas, however, breeding is likely to produce mostly low or medium density nymphs. Localised nymphs could develop from early December, but a significant regional subsequent increase in adult numbers is unlikely in January if conditions become dry.
  • There is a low probability of significant immigration from other regions during December or January.

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.

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Queensland

Southwest

Barcoo, Bulloo, Quilpie & Diamantina Shire

Locusts and conditions

  • Population density is expected to have remained very low in this region during November. Surveys during October identified only occasional Isolated density adults in all shires. Surveys in Quilpie and Bulloo Shire in mid-November detected very few locusts.
  • There was light rainfall (<20 mm) in parts of Diamantina, Bulloo and Quilpie Shires during the first week of November and further patchy light falls during 8-15 November. Pasture vegetation is dry in most of the region.

Forecast

  • Population levels will remain low during December. The occurrence of any heavy storm rainfall during December or January will influence the likelihood of any significant summer breeding and subsequent population increase.
  • There is a low probability of any significant immigration from other regions during December or January.

Risks

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

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 low in surveyed areas during November. Surveys in the Longreach, Barcaldine and Blackall-Tambo Regional Council (RC) areas identified Isolated–Scattered density adults in many areas. Previous surveys in Winton and Boulia Shires recorded only occasional adults.
  • There was heavy (>40 mm) rainfall in the Barcaldine and Blackall–Tambo RC areas in the first week of November and mostly light falls (<20 mm) in other areas. There were further moderate (20–40 mm) storm rains in the eastern half of the Central West in mid-November. Pastures vegetation is green in the eastern Central West region.

Forecast

  • Habitat conditions were favourable for locust breeding in the Barcaldine and Blackall-Tambo RC areas during November.
  • The presence of a spring nymphal generation and high density young adults in the Tambo area in October indicates a possible population that could breed and lay eggs at medium or high densities after the early November rains. Nymphs from a second generation would emerge in early December and fledge in early January. Medium density nymphs and some Bands could develop in localised areas, and result in an increase in adult numbers during January.
  • There is a low probability of any significant immigration from other regions during summer.

Risks

  • There is a moderate risk of localised second generation nymphs developing in parts of the Blackall-Tambo RC area during December. There is a low risk of more widespread regional infestations developing during summer.

Central Highlands

Central Highlands and Isaac Regional Council

Locusts and conditions

  • Locust densities remained low in the surveyed areas during November.
  • Surveys in mid-November identified only occasional adults in Isaac and Central Highlands Regional Council (RC) areas, with Isolated–Scattered densities near Taroom.
  • There was moderate-heavy rainfall (20->40 mm) in the region during the first week of November, after heavy rains in late October. Most heavy falls have occurred as localised storm rains. There was further patchy moderate rainfall during 15–22 November. There were some heavy falls in Banana Shire during mid-November and further light–moderate rainfall at the end of the month. Pasture vegetation is now green in many areas.

Forecast

  • Habitat conditions were favourable for locust breeding during November. Low density local egg laying could have commenced from early November, and continued in the Central Highlands RC area and Banana Shire later in the month. Given the low detected population numbers, this is likely to produce only localised nymphs.
  • Any nymphs resulting from eggs laid in November would develop during December and commence fledging at the end of the month.
  • 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 population densities were low in surveyed areas. Surveys at the end of October recorded Isolated–Scattered density adults in Paroo, Murweh and Balonne Shires. Survey of southern Paroo Shire in mid-November identified only occasional adults. Isolated–Scattered density adults were recorded in the Roma–Mitchell area.
  • There was light–moderate (<20–40 mm) rainfall in Maranoa and Western Downs RC areas, along with some heavy storms west of Roma, during the first week of November. There was further light–moderate rainfall in Maranoa and Western Downs RC areas during 8–15 November.

Forecast

  • Rainfall produced suitable habitat conditions for locust breeding during November, particularly in Maranoa and Western Downs RC areas. Given the low adult numbers detected, any egg laying is likely to produce only localised nymphs at mostly low densities. Nymphs would develop during December, but are unlikely to produce a large increase in subsequent adult population during January.
  • There is a low probability of significant immigration from other regions during December or January.

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.

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South Australia

Far North, Northeast, Northwest & Western Agricultural Region

Locusts and conditions

  • Locusts are expected to have remained at low densities during November, based on October survey data.
  • Surveys in the Northeast region in mid-November detected very few locusts in the Yunta–Peterborough area. Numerous density adults were identified at one location between Spalding and Burra.
  • Late-instar nymphs were reported to PIRSA in the Spalding area in late October.
  • The Oodnadatta light trap recorded low numbers of locusts in the first week of November. The Dulkaninna light trap is currently not operating.
  • There was moderate rainfall (20–40 mm) in the Northeast, Western Agricultural and parts of the Far North regions during the first week of November, with locally heavy (>40 mm) totals between Burra and Port Augusta. Pasture vegetation is green in areas west of the Southern Flinders Ranges, but will dry out during December without further rainfall.

Forecast

  • The rainfall in early November produced favourable vegetation and soil conditions for local breeding and egg laying, particularly in areas between Burra and Port Augusta and on the western side of the Flinders Ranges, particularly along watercourses. This could produce some localised low–medium density nymphs in early December, with the possibility of a few small Bands developing.
  • Nymphs would develop during December to fledge in early January, but mortality is likely in areas that become dry during the month, particularly in the Far North region. The distribution of rainfall during December will influence the survival of any summer nymph generation.
  • There is a low probability of immigration during December or January, given the low known population levels in the Far North and Northwest regions, and in adjacent regions of other states.

Risks

  • There is a low risk of widespread regional infestation during summer, but a moderate probability of localised nymphs developing in western areas of the Northeast region.

Murray Valley, Mt Lofty Ranges & Southeast Region

Locusts and conditions

  • The locust population level remained low during November. Survey of the Murray Valley in mid-November identified only occasional adults.
  • There was widespread moderate rainfall (20–40 mm) during the first week of November, with some locally heavy falls around Clare and at Lameroo.

Forecast

  • Rainfall in early November may have initiated some local breeding, but given the current low population level, there is unlikely to be a significant 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.

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Victoria

North West & North Central Victoria

Locusts and conditions

  • Locusts remained at low density in Victoria. There was no reported significant spring nymph generation and habitat conditions have been generally unfavourable for development.
  • Survey of the Mallee area of the Northwest region in mid-November identified only occasional adults, along with Present density fourth instar nymphs at one location.
  • Reports from Seymour and Yea in late November were investigated by Victorian biosecurity officers. Locally high densities of several grasshopper species, including Austroicetes vulgaris, were identified.
  • Low density adult locusts were identified by Department of Economic Development staff in the Elmore area, north of Bendigo in late November.
  • There was widespread light–moderate rainfall (20–40mm) across northern Victoria during the first week of November with localised heavy falls in the Murrayville area. The upper Murray area received further moderate rainfall during 8–15 November. Pastures are mostly dry in other areas.

Forecast

  • The locust population is expected to remain at low density during December and January, given its current low level and mostly dry vegetation conditions. Population levels in adjacent regions of NSW and South Australia are too low to provide any significant immigration during that period.
  • Rainfall in the Mallee and upper Murray areas could have initiated some local, low density breeding, but is unlikely to result in any significant population increases.
  • 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.

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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

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