Latin name: Spodoptera spp., Mythimna convecta and other armyworm species
Armyworms are destructive caterpillar pests found throughout Australia, particularly in lawns, sports fields, golf courses, pastures and agricultural crops. They are most active during the warmer months, with outbreaks often occurring after periods of rain followed by warm weather. Armyworm larvae feed voraciously on grass blades, often causing extensive turf damage within a few days.
The caterpillars are most active at night, hiding in thatch or soil during the day. Early detection is essential, as severe infestations can rapidly strip turf of its foliage.
Lifecycle
Armyworms undergo complete metamorphosis.
- Adult moths lay clusters of eggs on grass leaves.
- Eggs hatch into caterpillars that feed on turf foliage.
- Larvae pass through several growth stages before pupating in the soil.
- Adult moths emerge and begin the cycle again.
Several generations may occur each year under favourable conditions.
Identification
- Caterpillars grow up to 40 mm long.
- Green, brown or dark grey with pale stripes running the length of the body.
- Smooth-bodied with a distinctive inverted "Y" marking on the head in some species.
- Adult moths are brown or grey with a wingspan of 30–40 mm.
- Larvae hide in thatch or soil during the day and feed at night.
Damage
- Rapid defoliation of turf and pasture.
- Irregular brown or bare patches in lawns.
- Grass blades chewed to ground level.
- Increased bird activity as birds feed on caterpillars.
- Severe infestations can leave large areas of turf stripped within days.
SOLUTIONS
At the first signs of caterpillar feeding: Apply Apparent Surround to actively feeding larvae before significant turf damage occurs.
On lawns, golf courses and sports fields: Apply ProForce Rumbler 100SC to control armyworm larvae and protect high-value turf.
During peak moth activity in spring and summer: Inspect turf regularly for feeding damage and treat young larvae promptly with Apparent Surround.
Where recurring outbreaks occur: Monitor susceptible areas after rainfall and incorporate ProForce Rumbler 100SC into an integrated turf pest management program.
References
https://www.agric.wa.gov.au/pastures/armyworm
https://cesaraustralia.com/pestnotes/armyworm/
https://stratagreen.com.au/products/proforce-rumbler-1000sc-insecticide
https://stratagreen.com.au/products/apparent-surround-insecticide
