THE first locust hatchings in Victoria may only be a week away.

Australian Plague Locust Commission director Chris Adriaansen said wet weather expected this weekend tended to bring with it cooler temperatures, slowing down the development of locust eggs.

Cold weather over winter has now given many Victorian and NSW farmers a bit more time to prepare for a major locust attack.

The APLC has revised its forecast for locust hatchings, generally putting back peak hatchings from a few days to three weeks across most areas across eastern and central Australia.

But Mr Adriaansen said some locusts could emerge from their nests 10-14 days before the APLC’s peak hatching date while others were expected 10-12 days after the peak.

The APLC has kept peak hatching dates for the Mallee areas unchanged, while in central Victoria, locusts are expected to emerge about 10 days later than the last update bulletin released by the commission early last month.

In the Riverina, the estimated peak hatching dates have been put back by about seven to nine days, depending on the district.

Mr Adriaansen said the changes were made due to soil temperatures and other observations.

Hatching dates were dependent on soil type, with sandier country remaining warmer than heavier clay soils over winter.

He said landholders should start inspecting their properties about 14 days prior to peak hatching dates and continue to monitor them regularly until locust hatching was completed.

He said spraying should begin about two weeks after peak hatching.

The APLC has left peak hatching in the Mildura-Ouyen area unchanged at September 25, although the first locusts could emerge as early as September 11.

The Swan Hill-Boort area forecast hatching has been left unchanged at October 6, with some locusts possibly emerging as early as September 22.

Peak hatching in the Nhill-Warracknabeal area has been changed to October 17, with the first locusts possibly being spotted about October 3.

For the Horsham-Stawell area, the peak hatching has been put back three days to October 24.

The area from Shepparton to Tungamah now has a peak hatching of October 20 while the Echuca-Bendigo region’s forecast peak hatching is October 24.

In the Riverina, the APLC has estimate peak hatchings ranging from October 5 for the Hay-Balranald area to October 25 for the Wagga Wagga district.

Locusts go through five periods of growth known as instars, each about one week in duration and with a shedding of skin after each growth stage.

Farmers are encouraged to start spraying locusts at the second and third instar periods – when they form into bands crawling across the soil floor.

Locusts must be killed before they reach the adult stage and are able to fly.

Entomologist and locust expert David Hunter told the Birchip Cropping Group in June that by the second instar, most of the locusts would have hatched.

Mr Hunter said normally farmers should wait until all of the eggs had hatched before spraying.

He said the exception was if a band of locusts were heading from an exposed area into a crop.

He said that band should be hit with insecticide straight away but farmers should be prepared to spray the same area again if more locusts emerged later.