
Army worms are a caterpillar infestation which occurs on lawn grasses throughout Australia and the world, as well as feeding on many other crop species. The army worm is the caterpillar stage of a bownish/grey coloured moth species called Spodoptera mauritia. Their numbers often swell so quickly and in such high volumes, and cause such a high degree of damage, it literally looks like an army has been and attacked your lawn, and again, just like an army, when they are done with your lawn they will quickly all march to the next lawn to be attacked.
The life cycle begins when an adult moth will fly onto lawns at night time and lay pockets of eggs underneath leaves of the lawn. These tiny white eggs will hatch after around 10 days and become tiny army worms.
From here on, the army worms will continue to feed on the green leaf of the lawn at a voracious rate, always feeding at night time. They will then hide in the thatch layer or in the topsoil of the lawn during the day inside tiny cocoons, so they are rarely seen by people unless they specifically go out looking for these caterpillars with a torch, and on hands and knees.
The damage caused by the army worm will appear as large patches of the lawn literally being eaten away, with masses of grass leaves appearing on the top of the lawn which have been cut off at the base.
Army worms can be killed or controlled with several different pesticides which are available readily to the homeowner at local garden nurseries. There are both natural remedies which should always be used as a first defence, and more potent chemical pesticides.
All applications of pesticides to control army worm should be applied just before the sunset, as this is when the army worm will begin feeding, and will consume the pesticide at the same time as feeding. When using a product which comes in granular form, it will also need to be lightly watered to dissolve the chemical on the leaf of the lawn.
Repeat application may be necessary if the army worm infestation continues. Repeat the process once a week until resolved.
Highly respected Australian turf and plant breeder Todd Layt shares expert lawn care advice with homeowners on The Lawn Guide.