Grasshopper infestations

• Damage to crops and pastures by chewing leaves and stems.
• Most damage to pastures occurs in warmer months, with population booms usually following dry years.
• Preferential feeding on the legume component of improved pastures can damage newly established areas so severely that re-sowing is necessary.
• In the extensively grazed native pastures of Queensland, grasshopper population booms can severely reduce pasture feed base and ground cover.
• A grasshopper impact survey was developed in 2020 and repeated in 2021 to capture key impacts across the affected regions.

In February 2021, DAF established the Grasshopper Working Group, which includes representatives from DAF, the Australian Plague Locust Commission and the National Recovery and Resilience Agency.

The working group aims to ensure you, as producers, receive consistent information about grasshoppers and legal access to chemical control options. It also identifies research that could help predict and manage grasshopper populations in the future.

Chemical control

• The Australian Pesticides and Veterinary Medicines Authority has issued an emergency use permit for chemical products containing fenitrothion as control options for grasshoppers on pastures of the Mitchell grass bioregion.
• Always follow the approved instructions on permits and product labels—this is a legal obligation.
• Carefully assess the costs, benefits and risks of applying control options, such as:
  • the direct cost of the control
  • the cost of applying the control
  • the expected benefit from treatment
  • withholding periods for livestock and potential ecological influence.

Organic control

• Green Guard^® SC, Green Guard^® Premium and Green Guard^® ULV are formulated with the naturally occurring fungus Metarhizium, and are registered in Queensland with label instructions for use against grasshoppers.
• All 3 products have been used extensively where there are land use limitations on chemical pesticides (such as near waterways or wetlands or on certified organic production properties).
• Grasshoppers sprayed with Green Guard^® products usually die within 8–21 days after treatment, with mortality occurring more quickly in warmer weather. The products are most effective when targeting less-mobile, nymphal stage grasshoppers.
• Green Guard^® products could affect bees, so do not spray near flowering plants when bees are foraging.

• The grasshopper is not a prohibited or restricted invasive animal under the Biosecurity Act 2014. However, by law, everyone has a general biosecurity obligation (GBO) to take reasonable and practical steps to minimise the risks associated with invasive plants and animals under their control.
• Local governments must have a biosecurity plan that covers invasive plants and animals in their area. This plan may include actions to be taken on certain species. Some of these actions may be required under local laws. Contact your local government for more information.