One of the better Mallee cropping seasons in years could be facing an unwelcome threat, with Australian plague locusts now hatching across parts of the northern Mallee.
Agriculture Victoria confirmed on 23 September that locust hatching had begun in the region, with Mildura among seven Victorian council areas identified for priority surveillance.
The Mallee is currently considered to have a moderate-to-high risk of increased locust numbers this spring, following high numbers of adult locusts recorded earlier in the year.
It comes at a particularly important time for Mallee grain growers, with good winter rainfall and favourable growing conditions raising expectations for this year's wheat and barley harvest.
In other words, the rain that has helped produce an impressive crop has also helped create favourable conditions for locusts.
Highest numbers in 15 years
The warning signs have actually been building for several months.
Earlier this year, Victoria's Plague Locust Commissioner said locust numbers across north-west Victoria were the highest recorded in around 15 years.
Reports extended through parts of the Mallee, including around Mildura and south towards the Wimmera.
Adult locusts subsequently laid eggs before winter, leaving authorities watching closely to see what would happen once temperatures began increasing during spring.
That hatching has now started.
Good soil moisture and vegetation growth following the region's rain provide favourable conditions for newly hatched locusts to survive.
A big crop potentially in their path
The timing isn't ideal.
The latest national crop outlook from ABARES forecasts Victorian winter crop production at around 11.3 million tonnes, about 12 per cent higher than last year and 28 per cent above the 10-year average.
Crops across Victoria have also generally been developing several weeks ahead of normal following favourable conditions.
Statewide wheat yields are forecast to average around 2.9 tonnes per hectare, while barley is forecast at approximately 3.3 tonnes per hectare.
For Mallee farmers who have finally enjoyed decent rainfall through the growing season, the prospect of large numbers of locusts arriving as crops head towards maturity is something they'll be watching closely.
The combination makes this spring particularly unusual: potentially excellent crop production at the same time as the region faces its highest locust numbers in many years.
The next few weeks will be important
Newly hatched Australian plague locusts are tiny — only around four millimetres long.
They pass through five juvenile stages before eventually developing wings and becoming flying adults.
Agriculture Victoria says the most effective time to control them is generally around two weeks after hatching, when young locusts begin gathering together in what are known as hopper bands but are still unable to fly.
At that stage they can be targeted on the ground before they develop into mobile adult swarms.
Once locusts develop wings, controlling them becomes considerably more difficult.
Hopper bands themselves can also become remarkably dense, with Agriculture Victoria saying the leading edge of a band can contain between 1,000 and 5,000 hoppers per square metre.
The threat may not only come from Victoria
There's another factor authorities are watching closely.
Areas of south-western New South Wales and eastern South Australia are also considered to have a moderate-to-high risk of significant locust hatching.
Agriculture Victoria says there is consequently a moderate-to-high risk of locust movement into Victoria later in spring.
Australian plague locusts may travel around 20 kilometres during normal daytime movements, but under suitable migration conditions they can travel much further.
With favourable winds, migrating locusts can potentially travel hundreds of kilometres overnight.
That means controlling locally hatched populations is only one part of the picture, with authorities also keeping an eye on what's happening across the border.
We've been here before
The situation also brings back memories of the major locust outbreak of 2010–11.
During the 2010 outbreak, an Ouyen district cereal grower told the ABC that locusts had completely destroyed around 425 hectares of newly established canola, forcing the crop to be resown.
Victoria subsequently experienced its last major Australian plague locust outbreak during 2010–11.
There is currently no suggestion that 2026 will necessarily develop into a repeat of that event.
Agriculture Victoria's present assessment is a moderate-to-high risk of increased locust numbers, rather than a prediction that a widespread plague will definitely occur.
Farmers being asked to keep watch
Surveillance is now underway across the Mallee and other parts of northern Victoria.
Landholders are being encouraged to regularly inspect paddocks and surrounding areas for newly hatched locusts and hopper bands.
Early detection is particularly important because locusts are considerably easier to control before they develop wings.
For the Mallee, the next few weeks should provide a much clearer indication of just how widespread this year's hatch is.
After a season where rainfall has transformed paddocks across the region and given many growers the prospect of a strong wheat and barley harvest, farmers will be hoping the locust threat can be brought under control before it becomes another challenge standing between them and harvest.
Agriculture Victoria provides current Australian plague locust updates, identification information and advice for landholders at:
Agriculture Victoria – Plague Locusts
Out & About Sunraysia will continue following the locust situation across the Mallee as spring progresses.
