Unusually high levels of armyworm activity and damage have been reported in dairy pastures in southwest Victoria, Gippsland and Tasmania. Damage has been reported in perennial and annual grass pastures with some paddocks incurring significant and rapid loss of vegetation.
There are three native armyworm species that are pests of grasses and cereals in southern Australia.
Monitoring and control
Caterpillars are most active at night, seeking shelter under debris and vegetation on the ground during the day.
However, they can sometimes be seen during the day feeding on leaves and stems.
It is recommended to survey crops during the evening with a sweep net or bucket to determine the number and size of caterpillars with a direct ground search.
Armyworms are easy to recognise if they are present in reasonable numbers: they will be curled up on the ground if disturbed, or be wedged in the crown of the plant.
Look for signs of feeding on the edges of leaves, or evidence of caterpillar excrement in between the plants: 1–2 mm green pellets that look like mini hay bales.
Ensure that there is a large number of armyworms in the field before spraying.
There are a number of chemicals registered for control of armyworm. Always seek professional advice when using insecticides on pastures to ensure the correct choice is made for your farm and the environment.