Army Worm

Army worms are attracted from miles away to fresh lawn and fresh lawn shoots,

either recently acquired or recently fertilised.

(Just like throwing a fresh bale of hay in a drought ridden paddock)

The moths are widespread in suburban areas as they are attracted to lights.

Watch out for damaged / brown patches in your lawn

Use one of the following preventatives:

'Richgro Ant Killa'

‘Richgro 5kg Lawn Beetle And Grub Killa’

or ‘Scotts Lawn Builder + Grub and Insect Control’ when fertilising

(Fertliser + grub control is NOT for Zoysia Matrella)

*Bifenthrin is the ingredient to deter pests

Please Note:  While on the farm all turf is regularly treated for grub prevention.

Testing for Army Worms in your lawn

Water an area on your lawn and cover with a plastic bag (or similar) in the late afternoon. Come back during the night and check.

Pour a bucket of soapy water, which has been mixed up with some dishwashing detergent, over the lawn in a small area. The area is then monitored over the next 10 minutes to check for caterpillars which are coming to the surface.

Go out onto the lawn at night time and using a torch, get down low to the lawn and carefully run the torch over it looking for caterpillars feeding or crossing over it. Begin the search at the damaged area of turf, and spread outwards from there.

Leave the outside light on at night time for a few hours. Go outside every so often and check for moths flying around the light. If a multitude of moths are present, then this may be a sign of possible lawn caterpillar problems which will require further investigation.

Check your exterior walls for moth egg casings.

If you do find caterpillars, it is best to capture a few to take to the local nursery for positive identification. This will help the staff member recommend the right insecticide for the caterpillar type.

About Army Worms​

Army worms are commonly referred to as lawn grubs. This caterpillar of the Spodoptera Mauritia moth is most prevalent throughout the warmer months of the year (which Darwin has a lot of), and repeat infestations can occur.

The damage caused by Army Worms is most obvious by the speed at which damage occurs, as the caterpillars form very large numbers and behave as a colony to eat away at the green leaf of lawns.

Army Worms can vary in colour from green to brown to black, they can reach a maximum length of about 4 cm, and will become plump as they feed and mature.

These large numbers are possible due to the moth parent being able to lay up to 500 eggs in a single laying, and then repeat the same process the following night. This is where this lawn grub gets its name, it forms a large army, lays devastation to an area, and then will quickly move onto the next lawn once it has laid waste to yours.

Army Worms can also attack many other types of plants and vegetables, and the key to effective treatment is to identify and kill them as early as possible.

How to kill Army Worms

Once Army Worms have been identified, they are treated with a lawn insecticide which is freely available for purchase from garden stores, (eg. Bunnings) and nurseries.

The insecticide is mixed up and applied to the lawn just before dusk, before the grubs are about to feed.  Too early in the day and product is not as effective by the time they reach it that night.

Ensure to allow yourself enough time to finish the entire lawn treatment before night time.  The poison is then ingested by the Army worms as they are feeding on the lawn.

If the product requires watering in to your lawn then be careful not to over water, this will simply wash the poison away, and it will not be ingested by the caterpillars.

Repairing damage from Army Worms

Army worms will not generally kill a lawn by its feeding, but it will become heavily damaged, which if left untreated could cause patches of lawn to die. The only real thing to do at this time is to follow good practices, apply a quality fertiliser to the lawn and ensure it is getting adequate water. This will allow the lawn to best repair itself.

There is no need to either over-water, or apply excess fertiliser, doing either will not aid the lawn in repair, it may even cause further damage. Always apply fertilisers at manufacturer’s recommendations.


Please visit THE LAWN GUIDE website for loads of information on any care your lawn will ever need

Just click on the picture above or visit