Current Locust Situation and News

Locust situation February 2012

This page summarises the known distribution of locusts during January and provides a brief outlook to autumn 2012. The next Locust Bulletin will be produced in March 2012.

• Australian Plague Locust situation  
• Spur–throated Locust situation 
• Migratory Locust situation
• Map of forecasting regions

Australian Plague Locust (Chortoicetes terminifera)

Locust population density remained low throughout western Queensland, New South Wales, and in northern Victoria during January. A localised infestation of nymphs has developed in the Burra–Gladstone–Peterborough area of the Northeast region of South Australia and there were a number of reports of nymph activity and hopper bands in that area during the second half of January. There were few reports of locust activity in Victoria or Southeast South Australia, suggesting a continued population decline. Surveys indicate continued low background population levels in the Far West, Far Northwest, Central West and Riverina regions of New South Wales, and in Southwest, South Central and Central West Queensland.

The outlook is for an increase in adult densities in the infested part of Northeast South Australia, following the fledging of the summer generation of nymphs during February. Localised formation of a number of swarms is likely during the second half of February and this could result in some migratory redistribution within South Australia and the possibility of localised swarm egg laying. The development of small, higher density populations is still possible during late summer in parts of Southwest Queensland, Far West New South Wales or the Far North of South Australia. However, there is a low probability that this would present a migration risk to agricultural areas during autumn. The population level is expected to remain low in other regions of New South Wales and Victoria.

In South Australia, adult numbers declined in the Burra–Peterborough area during January, where there had been swarms during December, but there is now a generation of nymphs, following swarm egg laying in the area during the second half of December. Hatchings commenced in the second week of January and bands of mid-instar nymphs were reported from near Georgetown, Spalding, Gulnare, Yatina and Narridy during the second half of January. Nymphs will fledge from early to mid-February and further localised swarm egg laying could follow in parts of the region in late February or March. The background population in the Northwest and Far North regions remained generally low during January.

Surveys in New South Wales showed a continuing low density population in all regions during January. Adult numbers remained very low in the Central West, Northwest, Darling and Riverina Livestock Health and Pest Authority (LHPA) areas. There has been a small increase in population level over previous months in the Broken Hill–Wentworth–Balranald area of Western LHPA and occasional low density nymphs were identified in some locations in early January. A further increase in population is likely in parts of the Western LHPA area, which could result in sporadic higher density autumn egg laying. Localised medium density populations could develop in other LHPA areas in late summer, which could produce small autumn nymphal populations, although if this occurs it is unlikely to present a widespread threat to agriculture.

Surveys in Southwest, South Central and Central West Queensland identified a continued low density adult population. Despite further heavy rainfall in parts of these regions during January, there is unlikely to be a widespread population increase, since two generations are generally necessary to produce swarms from low density populations.

The absence of any areas of higher density adults in Victoria is an indication of the continuing decline in population level. There is a low risk of any significant population development during February or autumn.     

1 February 2012 

 Spur–throated Locust (Austracris guttulosa)

There is a widespread low density population of adults throughout the inland regions of New South Wales, Queensland and South Australia. Adults dispersed across most regions and commenced breeding in December in several regions of Queensland and northern New South Wales. Only occasional Present density early instar nymphs have been detected in parts of Central West and the southern Central Highlands of Queensland so far this summer. The overall size of the nymphal population this summer is much lower than that of 2010–2011. Any reports from landholders on the presence of nymphs of this species would assist in estimating the extent of the developing generation. The probability of a widespread infestation during 2012 has declined.

Surveys in Queensland during December and January identified consistent Isolated–Scattered density adults throughout the Northwest, Southwest, Central West, South Central and Central Highlands regions. Densities were highest in the Longreach–Muttaburra area, where there were consistent Numerous density adults in December. Adult numbers in the Dirranbandi area had declined to Isolated density in January. In New South Wales there were consistent Isolated–Scattered density adults in the Darling LHPA area. Adult numbers appear to have declined to Isolated density in the Northwest Plains and Central West LHPA areas.  There were Isolated density adults in Western and Riverina LHPA areas, and across northern South Australia. Adult densities have remained at Isolated–Scattered level around the southern Flinders Ranges area in South Australia.

With the continued rainfall during January, the outlook is for egg laying to continue in parts of the Central Highlands, South Central, Central West, Northwest and Gulf regions of Queensland during February. This species does not lay in dense egg beds and nymphs are generally not gregarious. Adults can lay multiple egg pods, so nymphs are likely to occur across several development stages during February and early autumn. Nymphs will fledge in March and April, so there will be a corresponding increase in adult densities in those regions.

The population reported in the Carnarvon area of Western Australia in early 2011 has persisted into this summer, where adult activity was again recorded during December and early January.       

Migratory Locust (Locusta migratoria)

APLC surveys did not detect this species during December or January. Low numbers of this species commonly occur in South Central, Central West and the Southern Highlands in Queensland and the New South Wales Northwest Plains during summer. It is capable of continuous breeding over several generations and the heavy rainfall which has continued from late spring to January in these regions could have allowed successful breeding of the low density population. There is the potential for the development of localised small gregarious populations of this species during February or autumn, although the probability of a significant infestation remains low.

Map of locust forecasting regions mentioned on this web page

Circles indicate locations of APLC light traps.