Locust situation 6 March 2017
This page summarises the known distribution of locusts during February 2017 and provides a brief outlook for autumn 2017. Regional information and forecasts are given in the latest locust bulletin.
Australian Plague Locust (Chortoicetes terminifera)
Locust populations declined to low densities in most regions during February. However, breeding in December in the Oodnadatta–Coober Pedy area of Northwest South Australia produced a nymph generation that fledged at the end of January. Widespread medium density adults were recorded in early February and transient swarms formed in the Oodnadatta area. Breeding also occurred in the Far North and Northeast regions, where young adults and late instar nymphs were identified in several areas.
The locust population level declined to low densities in New South Wales during February. Only occasional low density adults were identified in Central West and Northwest Plains regions, with more consistent counts in the Broken Hill–Tibooburra and Bourke areas of the Far West region. No nymphs were detected during surveys and habitat conditions are now generally dry in most regions.
In Queensland, consistent low density adults and occasional late instar nymphs were recorded in the Central West, South Central, Northwest and Southwest regions during February. Medium density adults were identified in the Birdsville area of Diamantina Shire.
In South Australia, a widespread population of medium density adults and mostly mid-instar nymphs was identified in the Oodnadatta–Mt Barry–Coober Pedy–Marla area in early February. A number of swarms were recorded in the Oodnadatta area, containing both immature and gravid females. Adult densities were low in most of the Far North region, but localised bands of late instar nymphs and medium density adults were recorded near Dulkaninna and Murnpeowie. More widespread low and medium density late instar nymphs were recorded from Hawker to Peterborough in the Northeast region. High density nymphs were also reported from the Ceduna area of the Western Agricultural region in mid-February.
Population levels remained generally low in Victoria. However, noticeable numbers of adults were reported in the Echuca–Mitiamo area in early February and persisted in northern Victoria throughout the month.
The autumn outlook is for locust population densities to remain generally low in most regions of New South Wales and Queensland. A decline in adult numbers is likely in the Far North, Northeast and Northwest regions of South Australia during March. However, there is the potential for a nymph generation to develop in localised areas of northern South Australia and possibly in Southwest Queensland during March if swarms laid in habitats made favourable by the heavy rainfall at the end of January. Adult numbers will increase in the Western Agricultural region of South Australia during March, with the possibility of localised swarm activity and sporadic egg laying. There is a moderate probability of low density migrations within South Australia during March and April, with the likelihood of some southward movements. Medium density populations could establish in southern South Australia and New South Wales, and northern Victoria during autumn. The majority of eggs laid in these regions in March or April will be at low densities and will remain in diapause dormancy during winter. There is a low probability of swarm infestations in any state during autumn. Consequently, there is a low risk of widespread nymph infestations developing in agricultural regions during spring.
Spur–throated Locust (Austracris guttulosa)
There was a widespread medium density population throughout inland Queensland during February, with a relative decline in breeding adult numbers detected in some regions. There were also widespread, low and medium density nymphs in Central West and Northwest Queensland, and similar populations are likely in to be the Queensland Gulf and Central Highlands regions. Low density nymphs were recorded in the Southwest and South Central regions.
Surveys in February identified Scattered–Numerous density adults in Central West and Northwest Queensland, along with Present–Numerous density nymphs, mostly at middle and late instar stages, at many locations. Present density nymphs and Isolated–Scattered density adults were recorded in Diamantina and Quilpie Shires in the Southwest and Murweh Shire in South Central Queensland. Occasional adults were recorded in the Far West and Northwest Plains regions of NSW.
Heavy rainfall was restricted to parts of the Central West, South Central, Central Highlands and Gulf regions of Queensland during February. This will enable nymphs currently in those areas to survive to fledging and some breeding to continue. Females can lay several pods over the course of the wet season. Egg development to hatching in this species takes 3–4 weeks and nymph development a further 8–10 weeks. Further nymphs are likely to develop during March, but hatchings should decline in April. Fledging of nymphs hatched in previous months will continue and the numbers of young adults will increase during autumn. These will largely replace the previous generation as it ages and declines, although some swarms are likely to form in late autumn. There is a low risk of a large increase in overall population level during 2016–17.
Migratory Locust (Locusta migratoria)
The Queensland Central Highlands region was not surveyed during February and this species was not detected in other regions. However, previous surveys identified low numbers of adults in the southern Central Highlands.
Rapid population increases can occur in the Central Highlands, eastern Central West and South Central regions of Queensland. Rainfall during February will produce favourable habitat conditions for continued localised breeding during autumn. Small gregarious populations could develop in localised areas of the Central Highlands, but there is a low probability of a widespread infestation developing during autumn or winter.
Locust Forecasting Regions
Map of forecasting regions with potential locust habitats shaded yellow