Current locust situation

Locust situation 5 March 2020

This page summarises the known distribution of locusts during February 2020 and provides a brief outlook to May 2020. Regional information and forecasts are given in the latest locust bulletin.

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Australian Plague Locust (Chortoicetes terminifera)

The locust population level remained very low in areas of New South Wales, South Australia and southern Queensland surveyed during February. Numerous regions received heavy rainfall during February and in parts of Queensland there were multiple rainfall events from late January to the end of February. Populations are expected to have remained generally low in those regions, but flooding has restricted access to surveys. Heavy rainfall across western Queensland and parts of New South Wales during February produced suitable habitat conditions for breeding by the limited populations in those areas.

Surveys of Southwest and South Central Queensland in mid-February identified only low density adults and no nymphs were detected. There was heavy storm rainfall (>40 mm) in the Northwest, Central West, South Central, Central Highlands and parts of the Southwest regions of Queensland during February. Rainfall totals >100 mm were received at many locations. Some sporadic breeding was possible during February and low density nymphs are likely to have developed in localised areas. Fledging of nymphs during March and April could result in a moderate increase in adult population from the current very low levels.

In New South Wales, surveys in Central West and Northwest Plains regions in mid-February recorded only occasional low density adults and no nymphs were detected. Occasional adults were recorded in the Bourke district, but no locusts were identified elsewhere in the Far West region. There were several periods of moderate–heavy rainfall (20-40 mm) in the Northwest Plains and Central West regions during February. Low density breeding was possible in localised areas, with some nymphs developing from late February. Fledging of any nymphs during March or April is likely to contribute to overall low population levels.

Surveys in South Australia in mid-February recorded no locusts in the Far North or Northeast regions. There was widespread moderate–heavy (20->40 mm) rainfall across much of the state at the start of February. Localised, low density breeding was possible during February, but is unlikely to result in a noticeable increase in the overall population level during autumn.

No surveys were conducted in Victoria during February. Some sporadic breeding was possible during February, but the overall population level is expected to remain very low during autumn.

The March–May outlook is for low population densities to continue in most regions of inland eastern Australia. Prolonged drought and associated poor habitat conditions prior to February reduced the adult population to very low numbers in all regions and several generations of successful breeding would be necessary for populations to increase to widespread high densities. However, the heavy rainfall in Queensland and in parts of New South Wales produced favourable soil and vegetation conditions for locust breeding and subsequent nymph survival. A generation of localised, low density nymphs likely developed in late February and breeding could continue during March in some areas. An increase in adult numbers to medium densities is possible in autumn in several Queensland regions, as well as the Central West and Northwest Plains of New South Wales. Habitats in some other regions are likely to become favourable, but only limited autumn breeding is possible.

There is a low likelihood of high-density populations or widespread infestations developing during autumn or spring.

Spur–throated Locust (Austracris guttulosa)

The summer breeding population level remains very low. The current adult population level is one of the lowest on record in the regions covered by APLC surveys. Surveys during February identified only Isolated density adults at one location in Southwest Queensland. However, survey of the Central West and Central Highlands regions has been restricted due to heavy rainfall and flooding. No nymphs have been detected during summer surveys. No adults were recorded in New South Wales, Victoria or South Australia.

Heavy rainfall in Northwest, Central West, South Central and the Central Highlands regions of Queensland during February is likely to allow continued egg laying and survival of nymphs in many areas. Although this species can lay multiple egg pods, the late arrival of the wet season in Queensland will limit reproductive capacity to the February–April period and nymphs may only develop during March–May. However, the very low background breeding population is likely to produce only low density nymphs. There is a very low risk of a widespread infestation developing during autumn 2020.

Migratory Locust (Locusta migratoria)

This species has not been recorded on any surveys during spring or summer. Vegetation and soils in locust habitats are favourable for breeding after rainfall in January and February in the Queensland Central Highlands, South Central and Central West regions. Breeding could continue throughout autumn in these regions. Gregarization and population increase often occur at local scales in habitats such as summer crops. However, a significant increase in population would require several successful generations.

There is a low risk of a widespread infestation developing during autumn 2020.

Locust forecasting regions

Map of forecasting regions

Map of forecasting regions with potential locust habitats shaded yellow

Last reviewed: 5 March 2020
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