This page summarises the known distribution of locusts during January and provides a brief outlook to April 2018. Regional information and forecasts are given in the
latest locust bulletin.
The very low locust population level during spring continued in December and January. No high density locusts have been detected or reported, despite rainfall producing short-lived favourable habitat conditions in many areas. Low numbers of locusts were recorded in the Riverina, Far West and Far Southwest of New South Wales, and the Central West, South Central and Central Highlands regions of Queensland during January. Small increases in population density were detected in the Central Highlands and South Central regions of Queensland, where localised breeding occurred during December. Although some localised low density breeding is likely to have occurred in other regions areas during December and January, most habitats dried out rapidly and extreme temperatures are likely to have caused increased mortality of nymphs and adults.
In New South Wales, surveys of the Riverina and southern Central West regions recorded low density adults and no nymphs were detected.
In Queensland, surveys of the Central Highlands and parts of the Central West and South Central regions in mid-January recorded consistent counts of low density adults, along with occasional late instar nymphs in areas south of Emerald. There were also medium density populations of other grasshopper species in the Central Highlands.
No surveys were conducted in South Australia and no reports were received. Habitat conditions are dry in most regions and, based on previous surveys, locust population numbers are expected to have remained low.
No surveys were conducted in Victoria and most reports were of wingless grasshoppers, Phaulacridium vittatum. Locust population numbers are expected to have remained low.
Reports received by the Department of Primary Industries and Regional Development in Western Australia indicate that medium density adults were still present in part of the Central Agricultural Region during January.
The outlook for February and autumn is for population densities to remain generally low in most regions of inland eastern Australia. Breeding is likely to continue during February and autumn, but given the current low population level there is a low risk of widespread regional infestations developing, and a very low risk of swarms affecting any agricultural region during autumn. The probability of a significant autumn nymph generation has declined, although localised higher density populations could develop if widespread heavy rainfall occurs during February.
There is a widespread low density population of adults in inland Queensland. Surveys in January recorded Isolated–Scattered density adults, along with low density nymphs, at many locations south of Emerald in the Central Highlands and in the Roma–Mitchell area in the South Central region. Nymphs are likely to have developed in other areas of South Central Queensland and in parts of the Central West, Northwest and Gulf regions during January, following heavy rainfall in recent months. Dry habitat conditions will increase nymph mortality in Northwest and Central West Queensland. The survival of nymphs to fledging will be influenced by rainfall during February in Central West, Northwest and South Central Queensland. Further egg laying will also depend on the distribution of heavy rainfall during February and March.
Fledging of nymphs will commence in February, with the bulk of those from this season’s breeding fledging during March and April. Young adults will gradually replace the current breeding population, but large population increases are unlikely except in the Queensland Gulf and Central Highlands regions. The likelihood of an overall population increase during 2018 compared to 2017 has declined, but the distribution, frequency and persistence of rainfall during February and March could result in a significant late cohort of nymphs.
Low numbers of adults were identified in the Queensland Central Highlands and South Central regions during January. Isolated density adults were recorded at several locations in Central Highlands and Maranoa Regional Council areas and in Banana Shire, and Present density late instar nymphs at one location near Capella. This species is common in these regions and rapid population increases are possible in favourable habitat. Gregarious populations can occur at local scales and are often associated with forage or cereal cropping.
Rainfall events in the Central Highlands and South Central regions of Queensland over recent months produced a sequence of suitable soil and vegetation conditions for breeding. Small gregarious populations could develop in localised areas during 2018. However, there is currently a low risk of a widespread infestation developing during autumn.