Locust Bulletin October 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 September and outlook to December 2015

Australian Plague Locust
Spur–throated Locust
Migratory Locust

Australian plague locust
Chortoicetes terminifera

The adult locust population declined to low densities in most regions during autumn. Swarm density adults laid eggs in eastern areas of Central West and Northwest New South Wales during March and April. Medium density adults remained in limited areas of the southern Riverina and Northwest Victoria and were likely to have laid eggs. Residual swarms in Central West and South Central Queensland could also have laid in localised areas. Egg laying in other regions was likely to have been at low densities, as only low numbers were recorded in Queensland and South Australia, and in Far West and Northwest New South Wales in April.

In Central West New South Wales, swarm egg laying was reported in the Gilgandra–Baradine–Coonamble and Coonabarabran–Mendooran–Dunedoo areas during March and April. Sporadic swarm egg laying also occurred in the Gunnedah and Narrabri districts of the Northwest Plains. Hatchings were reported in the Narrabri area in early September, and in the Gunnedah and Coonabarabran areas in mid-September. Hatching continued in the Central West at the end of September. A small mid-instar band was found in the Bourke area at the end of September with further localised high density hatchings possible in the Narrabri, Tamworth, Armidale and Barraba districts of the Northwest Plains. Surveys in mid- and late September did not detect nymphs elsewhere in these regions. Adults persisted during autumn in the Deniliquin–Wakool area of the Riverina, where medium and localised high density nymphs are likely to develop in October.

Adult densities declined in all regions of Queensland during April. However, residual medium density adults could have laid in localised higher densities within the South Central and Central West regions. Late instar hoppers were frequently found in the Tambo area from low to band densities, and a small band was also located in Charleville district at the beginning of October, but surveys in late September detected only low density adults in these regions. Hatching from overwintering eggs could have commenced in early September, and more localised high density nymphs could be expected.

Adult numbers declined in Far North and Northwest South Australia during April, following dry conditions and some migration in March. Rainfall during April–June in these regions provided suitable vegetation and soil conditions for egg laying by remaining adults, producing some localised medium density nymphs during September. Surveys found only low density adults in this region, and only localised areas of low density nymphs are likely to develop in other regions of South Australia.

Surveys in northern Victoria during late March detected a small population increase following some immigration. However, Department of Economic Development, Jobs, Transport and Resources staff identified up to medium density gravid adults at several locations in mid-April. Eggs laid by these adults could produce localised medium density nymphs in October.

The spring outlook is for areas of high density nymphs and numerous bands to develop in some eastern areas of the Central West New South Wales. More localised high density nymphs are likely in the Northwest and southern Riverina New South Wales, and Central West and South Central Queensland. Low densities are expected in the other regions of eastern Australia. Spring hatching will continue in Central West New South Wales, and commence in the Riverina and northern Victoria in early October. There is a low risk of widespread infestations across regions in spring.

7 October 2015

Spur-throated locust
Austracris guttulosa

There was a significant population increase in the northern half of inland Queensland during 2014-15, from the low levels of recent years. Widespread breeding occurred during December–February following repeated widespread heavy rainfall; breeding commenced in late November and the widespread heavy rainfall in December and January in Queensland initiated widespread, repeated egg laying in the Central West, Northwest, Queensland Gulf and Central Highlands regions. Fledging occurred during late summer and autumn and produced a consistent medium density population of immature adults in these regions, with high densities recorded in localised areas. Some swarm control was done by Biosecurity Queensland in the Central Highlands during autumn. Only occasional adults were detected in New South Wales and South Australia.

There were consistent low-density adults found in Central West, Central Highlands and South Central Queensland, and occasionally in New South Wales and South Australia from mid- and late-September surveys.

Adults aggregate in groups during winter and can form roosting swarms in trees along watercourses or in forest. Breeding commences in spring and egg laying is usually occurs after rainfall. The possibility of an early onset of the wet season in Northwest Queensland could initiate breeding in November. Some swarm movement and migrations are possible during spring, but no swarms were reported during August–September. There is a low risk of widespread regional infestations developing during 2015.

Migratory locust
Locusta migratoria

Medium and high densities persisted in the Queensland Central Highlands during autumn. Biosecurity Queensland conducted aerial control of swarms covering a total area of 20,000 ha in the Emerald and Clermont areas in early April. Swarms were also reported in Banana Shire in mid-April. Medium density adults and occasional swarms were recorded in the Blackall-Tambo and Maranoa Regional Council areas in autumn. Several swarms were identified in the Blackall–Yalleroi area of Central West Queensland in late March and occasional adults were recorded in the Longreach area.

Low-density adults were found localised in the Clermont and Springsure areas, and occasionally in South Central Queensland by surveys at the end of September.

This species is capable of producing multiple generations and continuous breeding in favourable conditions, although only limited breeding was likely during winter. Rainfall during winter was limited to several light–moderate falls in the southern Central Highlands and natural pastures are mostly dry. Gregarisation can occur at local scales, often associated with cropping in eastern Queensland, and can be difficult to detect without intensive surveys. Landholders are encouraged to report any swarms, egg laying or hatchings. There is a moderate probability of small gregarious populations developing in the Central Highlands region during spring.

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 15 September to 03 October 2015

Local Distribution Map

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Situation in September and forecast to December 2015

New South Wales

Central West

Central West and Central Tablelands Local Land Services

Locusts and conditions

  • Swarm activity continued in the eastern Central West region during March and April. Egg laying was recorded in Gilgandra–Coonamble-Baradine and Coonabarabran–Dubbo-Dunedoo areas. Numerous egg beds were identified by Local Land Services (LLS) staff, with the majority in locations to the east and south of Coonabarabran. Adult numbers increased in the Wellington–Parkes–Forbes and Tottenham–Tullamore districts. Migrations in mid-March resulted in locusts appearing in several south-eastern locations including Orange, Molong, Yeoval and Cowra.
  • Nymphs were reported near Mullaley in early August. LLS staff identified Numerous density mid-instar locust and other species nymphs.
  • Hatchings commenced in the Coonabarabran district in mid-September, with more than a dozen reports confirmed by LLS from Coonamble-Dubbo-Gunnedah area. In late September a number of small Bands developed.
  • Surveys in mid- and late-September identified Isolated density adults in the Warren, Nyngan, Coonamble districts, but no nymphs were detected other than those reported.
  • Most of the region received moderate total rainfall (20–40 mm) during July and August. There was only light rainfall (<20 mm) during September. Pasture vegetation is still green in most areas.

Forecast

  • A moderate spring nymph infestation is likely in the area bounded by Coonabarabran–Dubbo–Dunedoo. Hatchings are likely to continue in early October but the majority of nymphs are now at mid-instar stages and adults will fledge in late October and early November.
  • Hatchings in the Gilgandra–Baradine-Coonamble area have produced some small-sized Bands, but localised high density nymph infestations are also likely to have occurred elsewhere.
  • Any overwintering nymphs would have moulted into adults during September. These are likely to contribute to a small population increase in localised areas.
  • Nymph densities in the Narromine, Parkes and Tottenham districts are likely to be generally low, but could develop to Numerous–Sub-Band and Band densities in localised areas. Only low density nymphs are expected to develop in the Nyngan and Condobolin districts.
  • Fledging of adults will commence in late October and continue in November. Some swarm formation is likely in the Dubbo and Coonabarabran districts during November.
  • Pasture and soil conditions will remain favourable for nymph development during October in most areas.

Risks

  • There is a moderate risk of high density nymphs and localised Bands developing in the eastern Central West during spring.

Riverina

Riverina and Murray Local Land Services

Locusts and conditions

  • Migrations in mid-March resulted in a population increase in the Deniliquin–Moulamein area and sporadic high density egg laying occurred in late March and April.
  • Surveys in late September and early October only detected Isolated to Scattered densities of adults remaining in the Deniliquin–Moulamein area.
  • There was widespread rainfall during winter, giving moderate (20–40 mm) totals for July and August in most areas. The Narrandera and Corowa districts recorded >50 mm for August and there were further light falls in early September.

Forecast

  • Given the localised areas where high density adults were recorded in autumn, some nymph Bands may be expected to develop in the Deniliquin–Moulamein area during spring. However, egg laying was likely to have been more widespread during autumn and low–medium density nymphs could hatch in other areas, particularly in the eastern Riverina.
  • Most hatching will occur in early October in northern areas and nymphs will be at mid-instar stages in the second half of the month. The bulk of hatching in the Deniliquin area will occur in mid-October and will reach mid-instar stages by the end of the month. Fledging of the spring generation will occur during November.
  • Pasture vegetation was green during September and will remain favourable for nymph development in the Griffith, Narrandera, Wagga and Corowa districts during October. Without further rainfall ephemeral pastures will become dry in western districts during October.

Risks

  • There is a moderate risk of localised, medium–high density nymphs developing in the southern and eastern Riverina during spring.

Northwest Slopes & Plains

Northwest and Northern Tablelands Local Land Services

Locusts and conditions

  • The locust population increased in the eastern part of the region during autumn, as a result of local breeding and immigration. Sporadic swarm egg laying was reported in the Narrabri, Gunnedah, Tamworth and Liverpool Plains districts of Northwest LLS region in March and April. Medium and high density nymphs developed in a restricted area of the Narrabri district in September. Locusts were also reported in Armidale and Barraba areas in Northern Tablelands LLS in autumn and sporadic hatchings are likely in these areas.
  • Hatching was reported in the Narrabri district in early September. LLS staff identified small patches of Sub-Band–Band density early instar nymphs on properties east of Edgeroi and Narrabri.
  • Surveys in mid-September only identified Isolated density adults in the Narrabri, Walgett and Moree districts. No nymphs were detected in the western part of Narrabri district or other surveyed districts.
  • There was widespread winter rainfall in this region. Totals for June were >40 mm, and many areas received moderate (20–40 mm) totals for July and August. There were further light rainfalls in September, mainly in the eastern region. Pasture vegetation was green in the eastern areas of the region during September.

Forecast

  • Fledging of adults will commence in late October, contributing to a slight increase in adult population.
  • Vegetation will continue to dry out during October unless there is moderate rainfall.
  • There is a low probability of significant immigration during October or November.

Risks

  • There is a low risk of a widespread nymphal infestation during spring.

Far West

Western Local Land Services

Locusts and Conditions

  • After autumn emigration, there were only low-density residual adults widespread in this region, in addition to those that later developed from autumn nymphs.
  • The adult population was recorded at generally low densities in September. Only a 5x5m mid-instar Band was found in the north of Bourke on 29 September.
  • Surveys of the Broken Hill, Tibooburra and White Cliffs districts in mid-September identified Isolated–Scattered adults in most areas.
  • Surveys of the Brewarrina-Bourke-Wilcannia area in late September found occasional Isolated adults.
  • The Fowlers Gap and White Cliffs light traps recorded no locusts during August or September.
  • There was widespread rainfall in June and July, with some areas receiving >40 mm in June. There was patchy light–moderate rainfall (<20–40 mm) in August, but only light falls during early September. Pasture vegetation has started to dry out in most areas.

Forecast

  • Only a low density spring nymphal population is likely to occur, and adults will start to fledge in the second half of October.
  • Vegetation conditions remained suitable for nymph development in some areas during September, but will become dry during October in the absence of further rainfall.
  • There is a low probability of immigration during October or November.

Risks

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

Far South West

Western Local Land Services

Locusts and conditions

  • The adult population declined after autumn emigration and remained at generally low densities during September.
  • Surveys in mid-September found only Isolated to Scattered densities of adults, but in late September to early October early instar nymphs were found in a few locations at Present to Numerous densities.
  • There was widespread rainfall during winter, resulting in moderate (20–40 mm) monthly totals for July and August in most areas. There was only light rainfall (<20 mm) during September. Without significant rainfall, pasture vegetation will soon dry out.

Forecast

  • Most nymphs in this region will have hatched by mid-October and adults will appear in November.
  • There is a low probability of immigration during spring.

Risks

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

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

  • Adult numbers declined to low densities in April and the dry conditions were expected to have limited any breeding in the region.
  • Limited surveys in Bulloo Shire in mid-September identified occasional Isolated–Scattered density adults. No nymphs were detected.
  • The Nooyeah Downs light trap recorded no locusts during September.
  • There was light-moderate rainfall (<20–40 mm) in the Bulloo Shire during June, but no significant rainfall during July–September. Vegetation in surveyed areas was becoming dry.

Forecast

  • Any spring nymphs would have hatched during September. Habitat conditions are becoming unfavourable for nymph development and fledging in October is unlikely to contribute to a significant population increase.
  • Population levels will remain low in spring and any subsequent increase will be dependent on rainfall during November.
  • There is a low probability of any immigration during October, but this probability will increase slightly during November.

Risks

  • There is a low risk of a widespread nymph infestation in spring.

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.

Central West and Northwest

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

Locusts and conditions

  • Adult densities declined in these regions during autumn, although sporadic high density egg laying could have occurred in late March or April in the Barcaldine and Blackall-Tambo Regional Council (RC) areas.
  • Surveys of the Longreach, Barcaldine and Blackall-Tambo RC areas in late September to early October identified Isolated density adults in most areas, but Scattered and up to Concentration densities of adults were detected more frequently in the Tambo area.
  • Late instar nymphs were commonly seen in Present density in the Tambo area, and a Band was detected in Minnie Downs, 35km southwest of Tambo on 2 October. The 200m long Band was formed by 5th instar nymphs extending further 100m long in Sub-Band density.
  • After moderate-heavy (>40 mm) rainfall in the second half of June, there was no significant rainfall during the rest of winter, but eastern parts of the Blackall-Tambo RC area received moderate amount (20–40 mm) during August. Vegetation is very dry in Longreach RC area and in most shires of the Northwest region.

Forecast

  • Overwintering eggs in parts of Barcaldine and Blackall-Tambo RC areas could have produced more localised higher density nymphs in September. Given the consistent nymphs detected in Tambo area, fledging of the spring generation is likely to contribute to a small increase in the adult population level in some localised areas from early October.
  • The current dry conditions will limit breeding opportunities for adults. The location and amount of any rainfall in November or December, particularly from heavy storms, will influence the likelihood of egg laying and the extent of any summer generation.
  • There is a low probability of any immigration during October or November.

Risks

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

Central Highlands

Central Highlands and Isaac Regional Council

Locusts and conditions

  • Adult densities decreased during March, with a few Isolated adults found in surveys in late March.
  • Surveys in late September to early October identified only Isolated adults with no nymphs detected.
  • There was moderate (<20–40 mm) rainfall in the southern Central Highlands in the second half of June and further patchy moderate rainfall during late August. There was only patchy light rainfall (<20 mm) in the southern area in early September. Pasture vegetation was dry with some green base and stems in late September.

Forecast

  • Spring nymphs may have been widespread in Central Highlands RC area and a slight increase in overall adult numbers to Scattered density is likely in October.
  • There is a low probability of a significant nymphal infestation developing in this region during spring.
  • The location and amount of any heavy rainfall in October or November will influence the likelihood of significant egg laying and the extent of any summer generation.
  • There is a low probability of significant immigration during October or November.

Risks

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

South Central & Darling Downs

Balonne, Murweh and Paroo Shire. Maranoa, Western Downs and Goondiwindi Regional Council

Locusts and conditions

  • Adult numbers declined to low densities in April. However some sporadic high density egg laying could have occurred in localised favourable habitat areas.
  • Surveys of the Western Downs, Goondiwindi and Maranoa RC areas in mid-September identified only occasional Scattered density adults, but consistent Isolated density adults on many survey stops in the northern South Central Qld at the beginning of October.
  • A 100x70m late instar (4th–5th) band was verified by APLC staff at 60km southwest of Moven at a density of 100 per m2. A similar small band was found nearby and a few Present density nymphs were identified as late instars.
  • There was widespread moderate rainfall (20–40 mm) during winter and the further moderate falls during August in parts of Western Downs and Maranoa RC areas. Pasture vegetation response has occurred in areas receiving moderate rainfall.

Forecast

  • Adults will fledge from early October in the northern South Central Qld where the majority of nymphs were at 5th instar at the beginning of October, contributing to a small increase in adult population.
  • There is a moderate probability of localised high density nymphs developing in other parts of this region.
  • The distribution of any moderate–heavy rainfall in October or November will influence the probability of high density egg laying and of a significant summer generation developing.
  • There is a low probability of immigration during October, but the adults fledging from high density nymphs may redistribute within the region.

Risks

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

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

  • The Adult population declined dramatically in April due to emigration and drought conditions.
  • Despite rainfall during winter in the Far North and Northwest regions, only low density adults and limited account of Numerous density nymphs were detected by surveys in mid-September.
  • APLC survey of the Far North region in mid-September identified occasional Isolated density adults in the Innamincka–Moomba, Clifton Hills, Etadunna–Mungeranie areas.
  • Surveys in the southern Flinders Ranges area of the Northeast region identified only Isolated adults.
  • Light traps at Dulkaninna and Oodnadatta recorded no locusts during August or September.
  • There was light–moderate rainfall (20–40 mm) during May and June in the Far North, Northwest and Western Agricultural regions. Part of the latter region received heavy rainfall in early September. There were several periods of light–moderate rainfall in the Northeast region during June and August. Pasture vegetation remained green in low lying areas during September.

Forecast

  • Any spring nymphs in the Far North and Northwest regions will moulted into adults during October, which will not contribute to an obvious increase in overall adult population. Deteriorating vegetation conditions will limit breeding opportunities in the absence of rainfall in October or November.
  • There are limited areas of residual green vegetation along the Flinders Ranges, which could provide conditions for restricted egg laying. Dry conditions in most areas and in adjacent regions will limit opportunities for widespread breeding or swarm egg laying.
  • The distribution of rainfall will influence the likelihood and possible locations of any high density egg laying during November or December.
  • The is a low probability of significant immigration during spring.

Risks

  • There is a low risk of widespread regional infestations developing in spring.

Murray Valley, Mt Lofty Ranges & Southeast Region

Locusts and conditions

  • The autumn adult population declined to low density and remained low during September.
  • There were no reports of locust activity.
  • There was moderate–heavy rainfall (>40 mm) in western part of the region during July and August. There was further light–moderate (20-40 mm) rainfall in early September.

Forecast

  • Given the current low population level and dry conditions, there is only a low probability of a large nymphal infestation during spring.
  • There is a low probability of significant immigration during October or November.

Risks

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

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

  • Surveys in northwest Victoria during autumn detected a small population increase after immigrations in mid-March. Department of Economic Development, Jobs, Transport and Resources staff identified medium density gravid adults at several locations in April, and sporadic egg laying was likely to have occurred in a few locations.
  • Surveys near the Northwest Victoria – New South Wales border in the beginning of October only identified Isolated density adults.
  • There was widespread moderate rainfall in Victoria during each month of winter, and further light–moderate rainfall (<20–40mm) in Northwest and North Central Victoria during the first week of September.

Forecast

  • Hatchings will commence in northern Victoria in early October, but the bulk of any nymphs will appear in mid-October. There is a moderate probability of Present to Numerous density nymphs developing in localised locations in Northwest Victoria during spring.
  • There is a low probability of any immigration into Victoria during October or November.

Risks

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

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

Term

Definition

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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Locust forecasting districts

Local Distribution Map  

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