PestFacts WA

Monitor emerging crops for locusts and prepare for hatchings in Spring

• Allanooka
• Walkaway
• Esperance
• Albany

Australian plague locust adult. Photo courtesy of: DPIRD.

At the end of May Biosecurity officer Mike Jones (DPIRD) reported finding winged adult Australian plague locust (APL) in the Allanooka and Walkaway area. There were ~15 adults per square metre in patches, especially where there are grassy pastures.

Entomologist Svetlana Micic (DPIRD) reported low APL numbers across the state at the end of May. DPIRD surveys found isolated paddocks in the Esperance and Albany shire with less than 10 APL per square metre. The numbers did not pose a risk to emerging crops.

When there are higher numbers of APL (more than 10 per square metre) in pastures adjacent to paddocks that have emerging crops they may be at risk from APL damage, especially as there has been warm weather experienced during the start of this growing season.

Few APL are expected to be present now but growers will need to monitor paddocks that had APL activity in April and May for egg hatchings from mid-September. Sparse, open crops allow sunlight to penetrate initiating hatching and increasing the survival of APL nymphs.

How to identify Australian plague locusts

APL are sometimes found with a range of other, similar looking species of non-winged grasshoppers. The Australian wingless grasshopper (Phaulacridium vittatum), is often confused with the Australian plague locust, especially at the immature stage.

The Australian plague locust hopper (left) has a white X-shaped marking on the back of its thorax as its main identifier, while marking is more parallel in the Australian wingless grasshopper (right). Photos courtesy of: DPIRD.

APL always have an x-shaped marking behind the head. In nymphs this can be faded and becomes more visible with maturity, but it is always present.

An adult Australian Plague Locust. Photo courtesy of: Svetlana Micic (DPIRD).

Adult APL have a dark spot on the otherwise clear hind wing. The dark spot looks like an elongated smudge. They also have red tibia. This distinguishes them from all other species.

For more tips on identifying APL refer to DPIRD’s Australian plague locust: identification field guide page.

Managing Australian plague locusts

There are a number of chemicals registered for locust control including many that are used in canola paddocks for other pests. While synthetic pyrethroids may have been used in a knockdown mix these sprays are not going to have much residual value to protect crops now.

The best strategy is to monitor seeded paddocks for locust numbers and apply a direct application of insecticide if they are damaging emerging crops.

Sprays have better efficacy if applied early in the morning of a day that will be warm. APL adults are more likely to come into direct contact with the spray as they do not move quickly when it is cool. As the day warms up, adults will move onto sprayed vegetation and are more likely to ingest sprayed vegetation. Continue to monitor paddocks as locusts may reinfest a treated area.

For insecticide information visit DPIRD’s Australian plague locust control: registered insecticides page.

Further APL information can be found at DPIRD’s Australian plague locust overview page.

For more information contact Research scientist Svetlana Micic, Albany on +61 (0)8 9892 8591.

Article author: Cindy Webster (DPIRD Narrogin) and Svetlana Micic (DPIRD Albany).