This page summarises the known distribution of locusts during February and provides a brief outlook for autumn 2018. Regional information and forecasts are given in the
latest locust bulletin.
The locust population level remained low in most regions during February. Low numbers of adults were recorded in the Central West, Northwest Plains, Far West and Far Southwest of New South Wales, and in the Central West, Southwest and South Central regions of Queensland. Small increases in population density from very low levels in previous months were detected in part of Central West NSW and in Southwest Queensland. Although some localised low density breeding is likely to have occurred in other regions during January and February, most habitats dried out rapidly and prolonged high temperatures are likely to have caused increased mortality of nymphs and adults.
In New South Wales, surveys of the Far West, Far Southwest, Northwest Plains and Central West regions identified occasional low density adults in most areas. A localised area of high density young adults and residual late instar nymphs was identified in the Lake Cargelligo–Condobolin area of the southern Central West, indicating some breeding occurred there after heavy rainfall in December.
In Queensland, surveys of the Central West and parts of the Southwest and South Central regions identified low density adults, although recorded more frequently at transects than on previous surveys. No nymphs were detected.
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 likely to have remained very low.
No surveys were conducted in Victoria and the only report was of yellow-winged locusts, Gastrimargus musicus. Locust population numbers are expected to have remained low.
The outlook for autumn is for population densities to remain generally low in most regions of inland eastern Australia. Rainfall during February was dominated by heavy storm events in eastern and northern Queensland. This will maintain favourable habitat for locust breeding in the Central Highlands, Central West and South Central regions, although aggregation and high density autumn egg laying is unlikely. Sporadic breeding will continue during autumn, and an autumn nymph generation is possible in several regions of Queensland. The majority of eggs laid in NSW, Victoria and equivalent latitudes in South Australia during March will enter diapause and not hatch until spring. Given the current low population levels, there is a low risk of regional infestations developing and a very low risk of swarms affecting any agricultural region during autumn. At this stage there is no indication of high density nymph infestations developing in any region during spring.
There is a widespread low density population of adults in inland Queensland. Surveys in February recorded Isolated–Scattered density adults in Central West Queensland and Isolated density adults in the surveyed parts of the Southwest and South Central regions. No nymphs were detected in surveyed areas. Previous surveys recorded low density nymphs south of Emerald in the Central Highlands and in the Roma–Mitchell area of the South Central region. Several heavy rainfall events in parts of the Central Highlands and South Central Queensland maintained favourable habitat for continued egg laying and nymph survival. However, previously recorded adult densities were low. Rainfall distributions suggest nymphs are likely to have developed in the Queensland Gulf region. Dry conditions during February are likely to have increased nymph mortality parts of Northwest, Southwest and Central West Queensland.
Fledging of nymphs will continue during March and April, with the possibility of a late cohort in the Queensland Central Highlands and South Central regions that would fledge in May. 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.
This species was not detected by February surveys. Survey during January identified low numbers of adults in parts of the Queensland Central Highlands and South Central regions. Isolated density adults were recorded at several locations in the Central Highlands and Maranoa Regional Council areas, and in Banana Shire. This species is common in these regions and rapid population increases are possible in favourable habitat. Gregarious populations can develop at local scales and are often associated with forage or cereal cropping.
The sequence of rainfall in the Central Highlands and South Central regions of Queensland during February has maintained favourable soil and vegetation conditions for continued breeding. An increase in overall population level in possible during autumn. Small gregarious populations could develop in localised areas during 2018. However, there is a low risk of a widespread infestation developing during autumn.