Locust Bulletin February 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 January and outlook to April 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 January, with only small increases in adult numbers detected in a few areas. The population in eastern areas of Central West New South Wales declined to low densities and there have been no reports of further hatchings. Surveys identified low density adults in the Far West, Far Southwest and western Riverina regions of New South Wales, and in the Southwest, South Central, Central West and Central Highlands regions of Queensland. Very few nymphs were detected despite green vegetation in several regions, however some hatching from January egg laying surveys may have occurred late in the month. Heavy rainfall in northern South Australia and Queensland at the start of January, and further rainfall in Queensland, South Australia and New South Wales during the month produced favourable conditions for breeding and nymph survival.

Locust numbers fell to background levels in the eastern part of Central West New South Wales in early January and no subsequent nymphs have been reported. Surveys recorded low density adults in most areas of the western Riverina, Far West and Far Southwest regions, with medium density adults only recorded in localised areas of the Ivanhoe, Wentworth and Bourke districts. Very few nymphs were detected during surveys.

Surveys in the Central West, Southwest, South Central and Central Highlands regions of Queensland identified occasional low density adults in most areas, with more frequent low densities in the Charleville–Cunnamulla area, and in the Roma–Miles area where low density nymphs were also detected. There are widespread populations of Oedaleus australis and the yellow-winged locust, Gastrimargus musicus in the Central Highlands region. High density Gastrimargus nymphs have been reported from further north in the Charters Towers district.

Adult numbers are likely to have remained low in most regions of South Australia, but favourable habitat conditions in the Far North region and light trap catches at Oodnadatta and Dulkaninna during January indicate that some localised, low density breeding was possible in areas that received heavy rainfall.  Nymphs will develop during February, possibly with some small bands, followed by a moderate increase in adult numbers during March.

The locust population should have remained low in northern Victoria. Continued reports from areas north of Melbourne were identified as several grasshopper species.

The outlook for February is for localised nymphs developing in a number of regions following breeding in favourable habitats. This could occur in parts of the Southwest, Central West and South Central regions of Queensland, the Far North and Northwest regions of South Australia, or the Far West and Northwest Plains regions of New South Wales. However, nymphs are likely to be mostly at low–medium densities, with higher densities and some bands in limited areas. Most nymphs will fledge during March and overall adult numbers will increase into autumn. The absence of any known high density populations reduces the probability that late summer breeding will produce swarms in any region in autumn. There is a moderate risk of significant population increases or localised infestations in some regions in February and March, with subsequent small southward migrations during March or April. There is a low risk of widespread infestations affecting agricultural regions in several states during autumn.

4 February 2016

Spur-throated locust
Austracris guttulosa

There is a widespread low density adult population in inland regions of Queensland. Occasional Isolated density adults were recorded in the Longreach, Barcaldine and Blackall-Tambo Regional Council (RC) areas of the Central West in mid-January. Scattered–Numerous density adults, including some females with developed eggs, were identified in an area west of Muttaburra at the end of January and reports indicate similar densities in areas to the north and west of Longreach. Surveys identified Isolated–Scattered density adults in the Emerald, Springsure and Arcadia districts of the Central Highlands RC area, and similar adult densities in the Isaac RC area, along with some Numerous density adults near Avon Downs and Epping Forest. There were Present density early instar nymphs at a few locations around Clermont. In South Central Queensland, surveys identified Isolated density adults and some Present density nymphs at various stages of development in the Mitchell–Roma area. Isolated–Scattered density adults were recorded in the Thargomindah–Eromanga-Quilpie area of Southwest Queensland. Only occasional adults were identified in Far Western New South Wales.

Adult densities appear to have declined in areas of the Central West and Central Highlands of Queensland, compared to previous surveys. This could reflect a tendency to disperse during egg laying or continued redistributions during the breeding season. The small increase in numbers in Quilpie Shire also indicates redistribution of the breeding population to green habitat areas. The range of nymph stages in the Roma–Miles area of South Central Queensland suggests egg laying in that area from early December, while identified nymphs were younger in the Central Highlands. Widespread heavy rainfall during January will have allowed egg laying to continue in the Central West, South Central, Central Highlands and Gulf regions, and in parts of the Southwest region. The expansion of favourable habitat conditions in these regions will enhance the survival of nymphs and allow egg laying to continue during February. Females can lay multiple times during summer.

Nymphs of this species usually do not aggregate to form bands, but can reach densities of 30 m2 in favourable habitats. 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 occasional low density nymphs. Fledging of early nymphs will commence in mid-February and continue during autumn. Adult numbers will increase during autumn.

The heavy rains during January have altered the outlook for an overall increase in population during autumn to a higher level than in previous years. There is a moderate risk of localised swarm formation during late autumn 2016, particularly in the Central Highlands and Central West regions of Queensland.

Migratory locust
Locusta migratoria

Low density adults were identified in the Queensland Central Highlands region, and in eastern Barcaldine Regional Council (RC) area during January. Occasional Isolated density adults were recorded in the Emerald, Springsure and Arcadia Valley districts of Central Highlands RC area, and in the Alpha district of Barcaldine RC area. No nymphs were detected during survey. Heavy rainfall during January will maintain locally favourable habitats for continued low density 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.

There is a moderate probability of small gregarious populations developing in parts of the Central Highlands or eastern Central West regions of Queensland during autumn. However, the absence of any identified or reported high densities, or any nymphs at this stage of the season indicates a low probability of any infestations developing during autumn 2016. 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 Locust Commission.

back to top

Australian plague locust distribution 1 January to 31 January 2016

Local Distribution Map

back to top

Situation in January and forecast to April 2016

New South Wales

Central West and Northwest Plains

Central West, Northwest and Central Tablelands Local Land Services

Locusts and conditions

  • The infestation that persisted into December in Central West, eastern Northwest and northern Central Tablelands Local Land Services (LLS) areas declined to background levels in January. LLS offices received very few reports after mid-December from areas east of Dubbo and no egg laying or subsequent nymph hatchings have been observed.
  • High density late instar nymphs were reported from a property in the Trundle area and lower densities from near Forbes areas in early January.
  • Northern districts of Northwest LLS received heavy rainfall (>40 mm) during the first week of January and there was widespread moderate–heavy rainfall (20->40 mm) in the last week of the month. There was widespread moderate–heavy rainfall in the Central West and Central Tablelands LLS area during the last week of January. Pasture vegetation is green in many areas and will continue to respond in early February.

Forecast

  • The decline of the population in the areas east of Dubbo is likely to have resulted from adult ageing, migratory redistribution and natural enemies. Increased parasitism may also have contributed to the apparent absence of further nymphs. The population level in the eastern Central West LLS is likely to remain low during February and March. Adult numbers are likely to be higher in other areas of the Central West region during February, as a result of sporadic egg laying in December, although swarm formation is unlikely. Rainfall in late January could result in sporadic higher density egg laying, which would produce nymphs after mid-February.
  • Rainfall in early and late January in Northwest LLS districts provided suitable habitat conditions for locust breeding and nymph survival. Local egg laying was possible in eastern districts in mid-January and in most districts at the end of the month. Given the previous low population level in the region, only low or medium density nymphs are likely to develop in February, with the possibility of hatchings in early or mid-February.
  • There is a moderate probability of an overall population increase in Northwest and western districts of Central West LLS area during March and April, but only a low probability of widespread swarm formation.
  • There is a low probability of significant immigration from other regions during February or March.

Risks

  • There is a low risk of widespread infestations developing in these regions during February or autumn.

Riverina

Riverina and Murray Local Land Services

Locusts and conditions

  • Surveys indicated a continued low density population in the western Riverina and there were no reports of locust activity.
  • The Hay, Hillston, Deniliquin and Balranald districts were surveyed in mid-January. Only occasional Isolated density adults were identified in the Deniliquin, Hay and Balranald districts. There were Scattered density adults at several locations north of Hay. No nymphs were detected.
  • There was widespread light–moderate rainfall (<20­–40 mm), with some heavy falls (>40 mm) in the eastern Riverina, during the last week of January. Pasture vegetation remained dry in most areas in January, but will respond to recent rains in eastern 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 February or March.

Risks

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

Far West and Far Southwest

Western Local Land Services

Locusts and conditions

  • Population densities remained generally low in areas surveyed during January.
  • Surveys in mid-January identified occasional Isolated density adults in the Broken Hill, White Cliffs, Wanaaring, Cobar and Wilcannia districts. There were Scattered–Numerous density adults in the Ivanhoe–Mossgiel–Booligal area, and Scattered density young adults in the Bourke–Barringun area. Present density late instar nymphs were detected at one location near Pooncarie.
  • The Fowlers Gap light trap recorded low numbers of locusts during the first ten days of January. None were recorded at White Cliffs.
  • There was light–moderate rainfall (20-40 mm) in the Tibooburra and Wentworth districts during 17–23 January. There were further moderate moderate–heavy falls (20-40 mm) in the Bourke, Brewarrina and Cobar districts during the last week of January.

Forecast

  • The rainfall in some districts of the Far West and Far Southwest regions in late January will produce suitable habitat for some localised breeding, particularly in the Tibooburra or Bourke districts. However, the low adult population level in most areas is likely to produce mostly low density nymphs in the second half of February and survival could be limited if vegetation becomes dry.
  • Previous undetected breeding produced the young adults in the Bourke district, which could provide a breeding population in early February to take advantage of the late January rainfall in the Bourke and Brewarrina districts.
  • There is a low probability of significant immigration from other regions during February or March, but this could increase during autumn, depending on population developments in Queensland or northern South Australia.

Risks

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

back to top

Queensland

Southwest

Barcoo, Bulloo, Quilpie & Diamantina Shire

Locusts and conditions

  • Population density remained low in surveyed areas during January. There were no reports of locust activity.
  • Parts of Bulloo and Quilpie Shires were surveyed in mid-January. Only occasional adults were identified south of Thargomindah and between Thargomindah and Quilpie, where vegetation remained very dry. There were Isolated and some Scattered density adults in the Quilpie–Eromanga–Thylungra area, and Present density late instar nymphs were detected at one location south of Eromanga. Pasture vegetation was green in areas north and west of Thargomindah.
  • There was moderate–heavy rainfall (20->40 mm) in Bulloo, Quilpie and parts of Barcoo Shires during the first week of January. There was further light–moderate rainfall (20-40 mm), and some locally heavy falls in these Shires during 17–23 January.

Forecast

  • The two periods of rainfall in this region during January have produced favourable habitat conditions for locust breeding and will maintain green vegetation for nymph development in some areas during February. Although January surveys did not detect high density adults, localised egg laying was possible in some locations in mid-January and further laying could have occurred at the end of the month. This is likely to produce nymphs during February, most likely at low–medium densities, but some localised small Bands could develop. Most nymphs would not fledge until early March. Given the low adult population level detected, a moderate overall population increase is likely in March.
  • There is a low probability of significant immigration from adjacent regions during February or March, but some low density movement from Paroo or Murweh Shires is possible.
  • An increase in adult population is likely in March, but widespread swarm formation is unlikely.

Risks

  • There is a low risk of a widespread regional infestation developing in February or autumn, but localised population increases are possible.

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 level remained generally low in surveyed areas during January, but several periods of rainfall have maintained favourable habitat conditions in many areas.
  • Surveys in mid-January identified occasional Isolated density adults in the Longreach and Barcaldine Regional Council (RC) areas. There were Isolated–Scattered density adults in the Tambo area, with Present density late instar nymphs at one location.
  • The Longreach light trap recorded no locusts during January.
  • There was moderate–heavy storm rainfall (20->40 mm) in the Central West region, and patchy storms in Winton and Cloncurry Shire during the first week of January. There was further moderate–heavy rainfall in Longreach and Blackall-Tambo RC areas, and in Winton and Cloncurry Shires during 16–23 January, and again in parts of Longreach and Blackall-Tambo RC areas in the last week of the month. Pastures are now mostly green in the Central West.

Forecast

  • After a second month of favourable habitat conditions, no significant population increase has been detected in the Central West. The widespread green conditions may have limited the aggregation of adults. However, there is likely to have been some localised egg laying during January and hatching may have occurred late in the month. Nymphs are expected to develop in some areas during February, including parts of Longreach or Winton RC areas. Localised high density nymphs could form small Bands in some areas in February, and several development stages could be present at different locations. A moderate increase in overall population density is therefore expected during March, but at this stage widespread swarm formation remains unlikely.
  • There is a low probability of significant immigration from other regions during February or autumn.

Risks

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

Central Highlands

Central Highlands and Isaac Regional Council

Locusts and conditions

  • Locust densities remained low in surveyed areas during January.
  • Surveys in Isaac and Central Highlands Regional Council (RC areas) in mid-January identified only occasional Isolated and Scattered density adults around Emerald, northwest of Clermont and in the Arcadia Valley. Isolated–Scattered density adults were also identified in the Taroom district in Banana Shire. No nymphs were detected on survey.
  • There are widespread populations of other species throughout the region, including Oedaleus australis and Gastrimargus musicus. Oedaleus adults and nymphs were recorded at Numerous density in a number of areas. Gastrimargus adults were recorded at Isolated–Scattered density in Isaac RC area, but there have been a number of reports of high density G. musicus nymphs from the Charters Towers district to the north.
  • >There was widespread but patchy moderate–heavy storm rainfall (20->40 mm) throughout the region during the first and last weeks of January. There were also some light–moderate (<20-40 mm) falls in mid-January. Pasture conditions reflect the local variations in rainfall, with green or drying off vegetation in different areas.

Forecast

  • Habitat conditions were favourable for some localised breeding in Central Highlands RC during January and will provide further opportunities for egg laying during February. Given the low identified population level, any egg laying during February is only likely to maintain the overall low regional population density in autumn.
  • There is a low probability of any significant immigration from other regions during February or March.

Risks

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

South Central & Darling Downs

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

Locusts and conditions

  • Locust density remained generally low in surveyed areas during January, but numbers have increased in some areas in recent months.
  • Surveys in mid-January identified Isolated–Scattered density adults in Murweh and Paroo Shires, and in northern parts of Maranoa and Western Downs Regional Council (RC) areas. Present density mid- and late instar nymphs were recorded north of Roma and Miles. Consistent Scattered density young adults were recorded between Charleville and Cunnamulla, but no nymphs were detected.
  • There was heavy (>40 mm) rainfall in most areas of the region during the first week of January. There was further moderate–heavy rainfall (20->40 mm) during the last week of the month. Pasture vegetation is green in many areas.

Forecast

  • Rainfall during January maintained habitat conditions suitable for locust breeding in Maranoa, Western Downs RC areas and Murweh Shire, and has produced favourable conditions in Paroo and Balonne Shires. The heavy rains in early January may have initiated localised, low density egg laying and some nymphs may have appeared in late January. Further rains at the end of the month will enhance the survival of any nymphs and allow egg laying to continue. However, adult densities remained generally low in surveyed areas and breeding was likely to have been at low–medium densities. The bulk of any subsequent nymphs would not fledge until late February and a moderate increase in adult numbers is likely in March.
  • At this stage in the season, there is a low probability that further breeding will produce widespread swarms in autumn.
  • 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 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.

back to top

South Australia

Far North, Northeast, Northwest & Western Agricultural Region

Locusts and conditions

  • Locust densities are expected to have remained generally low during January, but habitat conditions became favourable for breeding in parts of the Far North and Northwest regions. No surveys were conducted and there were no reports of locust activity.
  • The Oodnadatta light trap recorded low numbers of locusts each night during 1–18 January. The Dulkaninna light trap recorded low numbers locusts during 5-11 January.
  • There was moderate–heavy rainfall (20->40 mm) in the Far North region during the first week of January. Some locations around Lake Eyre received >100 mm. There was further patchy light–moderate rainfall (20–40 mm) in parts of the Northwest and Far North regions during 8–16 and 17–23 January.

Forecast

  • The rainfall events during January produced suitable habitat conditions for locust breeding and may have initiated sporadic, mostly low density egg laying several times during the month. Given that previous surveys identified only occasional adult locusts in the Far North region, and that population levels in adjacent regions were also low, any egg laying is only likely to produce localised low–medium density nymphs in February. However, some high density nymphs could develop in restricted areas of favourable habitat in February, but are unlikely to result in significant swarm formation in March or April.
  • It is also possible that some breeding commenced in late December, and that rainfall during January produced suitable conditions for nymph survival. Those nymphs would fledge in early February, maintaining regional population densities, but would be unlikely to be at high enough densities to breed and produce further high density nymphs in March.
  • There is a low probability of any significant immigration from other states during February or March.
  • There is a low probability of migrations between South Australian regions during February, but some redistribution is possible in autumn if there is successful breeding in the Far North region.

Risks

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

Murray Valley, Mt Lofty Ranges & Southeast Region

Locusts and conditions

  • The locust population is expected to have remained at a low level during January.
  • There was light–moderate rainfall (<20-40 mm) in parts of the Murray Valley and Southeast regions during each of the last two weeks of January.

Forecast

  • There is a low probability of any high density breeding or a large population increase during February or autumn.
  • There is a low probability of any significant immigration during February or March.

Risks

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

back to top

Victoria

North West & North Central Victoria

Locusts and conditions

  • Locusts are expected to have remained at low densities in Victoria during January.
  • Low density locusts, mixed with several grasshopper species, were reported in the Rochester district in early January. There were also continued reports from areas north of Melbourne during January, which have been identified as mixed grasshopper species.
  • There was localised light–moderate rainfall (<20–40mm) in part of North Central Victoria in the first week of January, light–moderate falls in the Northwest during 16–23 January, and again in the North Central regions in the last week of the month.

Forecast

  • The locust population is expected to remain at low densities during February and autumn. At this stage in the season there is insufficient time for local breeding to produce a significant population increase during autumn.
  • There is a low probability of immigration into Victoria during February and March.

Risks

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

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