Lawn Grub – Control and Prevention

Hello again,

Now it is time for the 2nd issue that MAY have a detrimental effect on your lawn –


Lawn Grubs (Spodoptera spp.) – feed of the fresh, young, green leaf of your turf just above the ground. They drastically reduce the quality and growth of your turf.  This photo below displays a typical lawn affected by Lawn Grub –


Common symptoms are  – brown, dry and brittle turf. Closer inspection reveals the leaf blade of the turf to be eaten by something (as this photo displays). The actual lawn grub looks very similar to a caterpillar. (as this photo displays). They are range in colour from bright green to dark green / brown in colour with black dots down there back.


*NOTE – Lawn grubs are also known as ‘Armyworm’. This is because they start in one section of your lawn and work their way across the lawn along a set line, similar to soldiers in a battle.

Lifecycle – To best understand how to control and PREVENT lawn grubs it is best to understand there lifecycle. The lifecycle of the Lawn Grub is explained below –

Beet Armyworm Life Cyclepiknik

The adult Lawn grub is actually a moth, brown in colour. Please see the photo below –

armyworm_adult2piknik The adult female moth flies around at night and is attracted to well maintained lawns. She lays her eggs into soft cocoons on the awnings of your house, under side of leaves and even your clothes line. These cocoons look like this –

armyworm eggspiknik

These cocoons then hatch into the caterpillars (or LARVAE). These caterpillars are the ones (lifecycle stage) that do the damage to your lawn. They will live for approx 3 weeks if allowed to. However it is best get rid of them ASAP.

lawn grub identificationpiknik

So how do we get rid of Lawn grubs ?

Control Methods –

Chemical control: A range of insecticides are registered for the control of Lawn grub in turf.  These are readily available from your local hardware or nursery. If possible spray late in the day as the Lawn Grub / Larvae are active at night.

Cultural Control : By breaking the lifecycle of the lawn grub you are able to PREVENT any lawn grubs getting into your lawn in the first place. This is best achieved by keeping an eye out for the soft cocoons on your awnings and gardens and either brushing or hosing them off. This will kill the eggs, hence not allowing the Lawn Grub / Larvae to eat your beautiful lush lawn.

Additional info – Lawn grubs are more likely to occur after rainfall. This is because the grass is lush and green. Therefore keep an eye out for the moths and cocoons after rain.

*Turf recovery  – even if your lawn has been completely eaten by lawn grub (lawn looks brown, brittle and dead). Your lawn will recover. The best thing to do is –

1). apply a chemical insecticide to kill all of the existing lawn grubs (make sure that you do this first BEFORE fertilizing, as if you fertilize first you will only be ‘feeding’ the existing lawn grubs).

2). Fertilize your lawn with ‘Scotts Lawn Builder + Grub and Insect Control’. Found in Bunnings aLBInsectkill_2.5kg_LRnd most local hardware stores. This product will fertilize your lawn to enable a quick recovery and will also ensure that NO lawn grubs survive.

3). Water / irrigate your turf for 2 – 3 days after applying fertilizer to ensure a quick recovery !

I hope that this info helped !

If you have any questions specifically about turf please feel free to email them to us at


  1. Sare - Coastal Turf says:

    I would suggest stopping the spraying because I think you may miss some of the more dormant larvae. I would suggest getting some of the sand granulated lawn grub killer. Like Brigade or The Scotts Ant and Army worm killer is great as well. By having the insecticide in the lawn for 3 months means you get all the larvae now and in the near future.
    I would suggest top dressing the lawn with a good garden mix soil and this will food your lawn up coming into winter. Maybe just before rain?

  2. Amelia Ypung says:

    What is the best product to kill an army worm? They started to appear on out lawn this week, specifically last Monday?

  3. Sare - Coastal Turf says:

    Hi Amelia,
    This weather at the moment is perfect for the nasty little grubs to come out.
    I prefer the sand granulated insecticides, such as Brigade or the Brunnings Ant and Army Worm killer as I know its safe for my kids and pets.
    Good luck with them!

  4. Hi there,
    Would the sand be a safer option for birds than spray?
    I’d hate to harm them.

  5. Sare - Coastal Turf says:

    I know that the sand based insecticide is specifically designed to kill only grubs. The Magpies may just be upset that there is not enough bugs on your lawn for them.

  6. I’ve just used the sand granules on my lawn, all over. Just wondering how long I wait now until I start to fertilise and bring the lawn back to life?

  7. Sare - Coastal Turf says:

    Hi, Congrats on getting on to it and killing the nasty little things. I would wait 10 days and do a test to make sure that the grubs are gone. If they are, then apply a fertiliser to kick it on. Like a water soluble spray or a top dress to revitalise your lawn.

  8. Sare - Coastal Turf says:

    Hi Quinton. Are there dollar spots on your lawn? This is usually a fungus. Dollar spot infections require a fungicide to kill it off before it kills your lawn. If you are concerned it is fungus, please spot watering as water often feeds fungus infections, helping it to kill your lawn.
    Lawn grubs are really hitting lawns hard this year. I’m glad you got off the eggs but keep an eye out for their return.
    I would suggest that if you are really concerned I would contact a local lawn specialist on the Sunshine Coast to assess your lawn, see if you have a fungus infection or a second or third generation of lawn grubs. Sometimes you just need feet on the ground to diagnose. Sorry I cannot send Tony the Turfman out but we are not Tweed Coast in NSW.
    All the best

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