This page summarises the known distribution of locusts during January and provides a brief outlook to April 2015.Regional information and forecasts are given in the latest locust bulletin.
A large nymphal generation developed in several regions of Queensland and New South Wales during January. Hatching of eggs laid by adults during December produced many small bands from early January in parts of South Central, Central West and Southwest of Queensland, and in Central West New South Wales. Localised nymph bands also developed in adjacent areas of the Central Highlands and Northwest regions of Queensland, and the Far West and Northwest regions of NSW. Landholders carried out control of Bands in South Central Queensland and Central West New South Wales. Nymphs developed rapidly and mass fledging commenced in late January, resulting in the formation of numerous swarms.
In New South Wales, the highest concentration of nymph bands was in the arren–Gilgandra–Tooraweenah–Coonamble area of the Central West. Swarms were reported from this area in late January. Some isolated small bands were also reported from the Burren Junction, Moree and Collarenebri areas in the Northwest, Louth in the Far West, and Hillston in the Riverina. Adult numbers remained generally low in most regions in the first half of January, but following light trap catches in mid-January, several swarms were identified in the Fowlers Gap area of the Far West in mid-January.
Bands were reported from numerous locations in South Central Queensland during January, including the Roma–Injune, Wondoan–Taroom, Miles–Condamine–Meandarra, Goondiwindi–Moonie and St George–Thallon areas. Swarms formed in these areas in late January. Bands of late-instar nymph and swarms of young adults were identified in the Longreach–Muttaburra–Winton and Isisford–Yaraka areas of the Central West region in mid-January. In the Southwest region, high density young adults and swarms, along with residual nymphs were identified in the Warbreccan–Lochiel, Windorah–Morney, Retreat–Araluen and Nockatunga areas in late January. Medium density adults and low density nymphs were found in other areas of Quilpie, Barcoo and Bulloo Shires.
Locust densities remained low in most of South Australia, but localised high density nymphs and swarms of young adults developed in the Cordillo Downs area of the Far North region in late January. Light trap records indicated migrations in northern regions in mid-January, but subsequent surveys did not detect a significant population increase. However, sporadic egg laying is likely to have occurred in favourable conditions produced by heavy rainfall at that time.
Locust densities remained low in Victoria during January. Only occasional low density adults were identified in the Northwest region and near Echuca in late January.
The outlook is for a significant adult population and swarms in South Central, Central West and Southwest Queensland and in Central West New South Wales during February. Swarm movements will expand the areas of infestation and the risk of long distance migrations will increase. Egg laying by the swarms that developed at the end of January is likely to commence before mid–February, resulting in nymphs from the end of the month. An earlier, localised nymphal generation could develop in parts of Far West New South Wales and Far North South Australia. The locations of swarm egg laying will be influenced by habitat conditions, which are currently favourable in parts of South Central Queensland and Central West New South Wales, but the probability of a widespread autumn nymphal generation will be determined by rainfall distribution in February and March. Migrations during February could result in population increases in Far West, Northwest or the Riverina of New South Wales, or the Far North and Northeast of South Australia.
Adult population remains generally low throughout inland Queensland. Surveys during January identified Isolated–Scattered density adults in the Central West, Northwest, South Central and Central Highlands regions of Queensland. Occasional adults were identified in Far West New South Wales.
The current adult population commenced breeding in regions where there was heavy rainfall in late November and December. Surveys in January identified low density early–mid instar nymphs in the area south of Rolleston in the Queensland Central Highlands, and the Tambo area of the Central West region. There was a report of mid-instar nymphs from the Miles–Roma area in mid-January. In late January low density nymphs were identified in the Muttaburra area in Central West region. Adults can lay multiple egg pods during the summer wet season, so the distribution of further rainfall during February–March will influence the duration and success of the breeding cycle. Further heavy rainfall received during January will favour nymphal survival and continued egg laying by current season adults. Low density egg laying is likely to continue in the Central Highlands, Gulf, South Central and Central West regions of Queensland, and to have commenced in parts of the Southwest region. Fledging of nymphs will commence in February and will continue through autumn. The current low adult population level indicates that breeding is likely to produce a moderate overall population increase in 2015.
In late December, localised swarms developed in the Buckland Plains area, southwest of Springsure in the Queensland Central Highlands. Gregarious egg laying was observed by landholders on several properties, who reported early instar nymph bands at the start of January. In response to these reports, surveys in early January identified numerous bands of early and mid-instar nymphs on several properties in that district and a single small swarm south of Rolleston. Landholders carried out ground control of hopper bands and Biosecurity Queensland conducted aerial control in the Buckland Plains area on 17 January. Surveys identified low density adults in the Roma–Morven and Augathella–Tambo areas in mid-January. Adults were reported from the Clermont area and nymphs from the Condamine area South Central Queensland.
The continued widespread rainfall in most regions of Queensland during January will favour nymphal development and potentially further localised breeding during February. The bulk of nymphs in the southern Central Highlands will fledge in early February and localised swarm formation and swarm movements are likely. Habitat conditions are favourable for further high density egg laying in the Central Highlands, which could produce a further nymph generation in late February. However, this species is capable of continuous breeding, which can produce regional populations with all lifestages present. Low density adults identified in parts of South Central and Central West Queensland indicate that breeding and localised population increases could also occur in these regions. Gregarisation of this species can occur at local scales, often associated with cropping in eastern Queensland, and can therefore be difficult to detect without intensive surveys. There is a moderate risk of further localised gregarious population developments and of a significant population increase in the southern Central Highlands region during February and autumn.