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Australian plague locusts

Continued widespread heavy rainfall during summer and autumn has created favourable conditions for the development of Australian plague locust (Chortoicetes terminifera) populations in parts of New South Wales, South Australia and Victoria. To date, we have received numerous reports of locust activity in parts of western and north-western Victoria, and southern New South Wales. In several instances locusts have been reported attacking early-sown crops emerging in these regions, including canola and wheat.

The current locust swarms have resulted from widespread summer rains in locust breeding grounds in the northern Channel Country areas of south-west Queensland and adjacent areas of South Australia, New South Wales and the Northern Territory. Rain has created ideal conditions for locust breeding, triggering significant egg hatch and providing an abundance of green material for locusts to continue their development and build up to large numbers. Adults have subsequently migrated hundreds of kilometres south on favourable winds into southern cropping areas looking for green feed.

Growers and agronomists in all cropping regions should remain vigilant and continue to be on the lookout for locusts on their properties and in surrounding areas. The current adult locusts are likely to remain active until around mid-June, before they die off with the onset of colder weather. At the moment, it is particularly important to be on the lookout for any egg-laying activity, as this is likely to mean high numbers of locusts hatching in spring. Female locusts prefer to lay eggs into hard, bare ground or heavy soil types, although some laying in lighter soils has been observed. Where significant egg-laying has been detected, deep cultivation is thought to help reduce egg survival.

Any significant locust activity should be reported to your relevant Department of Primary Industries or directly to the Australian Plague Locust Commission (APLC). The APLC undertakes monitoring and forecasting of locust populations in inland eastern Australia throughout the year. They also coordinate broad scale control programs across Queensland, New South Wales, Victoria and South Australia. The New South Wales plague locust commissioner, Ross Burton, says control efforts this year have been made particularly difficult because seasonal conditions have resulted in low to medium densities of mixed-age locusts spread across a wide area.

Locusts are notoriously difficult insects to control as large populations can move vast distances in a short period of time. In addition, adults have been known to feed in paddocks during the daytime but may move several kilometres away each night to roost in sheltered areas such as remnant vegetation or windbreaks, before resuming feeding in the paddock the following day. Ideally, locusts should be controlled as ‘hoppers’ when they are unable to fly. However, if targeting adult locusts with chemicals, spraying should occur when they are settled, either in the late evening or very early morning. Adjacent paddocks, particularly pastures, should also be monitored and treated if required.

Australian plague locusts can cause severe damage to pastures and a range of field crops if they are not controlled. They are readily distinguished from other locust species by the large dark spot present on the tip of each hindwing and red coloured shanks on their hindlegs. Adults are up to 40 mm long with a variable body colour of grey, brown or green. They are the most important pest species of locust in Australia due to the area infested and frequency of plagues. Click here for images of the Australian plague locust.

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