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. Sorry I said John Wyatt and it was a question from Gilbert Whyte

  2. Hi Kellie,

    So to begin with the runners across your dead patches are very very good! It means that your lawn is trying to repair itself. Palmetto like most turf grass sends it runners across the ground and the. At the joints(where the leaves usually come off the stem) they send down little roots. This allows the palmetto to establish itself where it can find food or water rather than sending out millions of runners and some dying off, it sends them to where the plant is already being feed.

    The moths you are describing are similar to what I have seen as the adult form of the lawn grub. You may not be able to see the grubs at the moment due (pending on where you are) weather variations – like extreme rain and or heat and the grubs have gone deeper into the lawn to survive, life cycle, and the different areas that are in your lawn.

    Tunnel ants will most likely be causing your piles on your lawn. They have a detrimental effect on your lawn as well.

    I really strongly suggest that you get yourself some ant and lawn grub sand from your local nursery. The Scott’s brand is great or a mixture called Brigade is wonderful. If you are getting the aim we are out it out now and then in 10 days. The sand mixtures are water activated so now is a great time. Also the lawn grubs tend to spring into life after rain- kinda like Mosquitos.

    Hope you get Ll the nasty little things in your lawn. Palmetto is very aggressive as a turf grass so it should make a quick recovery. I would also suggest that in the change of season that you give your lawn a top dress and feed to help it fully recover before winter.

    Chat soon

  3. Samantha. Just a quick word of warning that after this huge lot if rain the lawn grubs will be back in force! I would reapply the lawn grub killer straight away!
    Hope your lawn is returning
    Chat soon

  4. Hi

    We have lawn grubs, but we also have 2 rabbits. How long after using an insecticide on the grub infected lawn before we can let the bunnies eat the grass again???

  5. Hi,
    I think the time before animals and kids can again rein the yard depends on what type of insecticide you are using. Try checking the back of your insecticide for full details. Sorry I can’t be more help.

  6. Thank you for this informative article on the Lawn/Army Grub. I have just treated my entire back lawn (large area) with Munns Granules and it killed them within a few hours after watering in during early evening. There were so many it was amazing. As my lawn was badly affected ( I initially thought was due to lack of water and very hot weather) do I have to cover with a layer of new soil? Amongst the lawn there are a lot of bare patches and dead grass. Some have shoots so not sure if all will recover?
    Thanks again

  7. Hi Paula, It depends on what tyoe of grass you originally had as to how quickly the grass should recover the dead patches. But Turf grasses grow from runners so it should recover. Just watch out for nasty little weeds trying to get in first in the dead patches. So glad the article helped you and you got onto the cause of your lawn problems. Don’t forget to look around covered areas and eaves to get rid of any eggs that are left. Thanks again for the positive feedback. Sare

  8. Hi, yes lawn grubs are out, I say… We are in qld and with all the rain, our back lawn came back to nice lush green and now the lawn grubs got into it. Heaps of dead army worms about. The front lawn is still nice and green. Have also treated it just in case with that spray on stuff. We have blue couch grass, quite hardy, so hoping it will come back quickly. Do you think we should still fertilise with the Scott’s lawn builder and insecticide? Ou neighbours have the sir Walter buffalo. Nice and green, I did warn them about lawn grub…sicknof cleaning the brown stuff from underneath the eaves, but it is not as much now.

  9. I suppose the question I have now is how long before I should re treat the lawn?

  10. Hi Tanja,
    I think the meanest thing about lawn grubs and the lawn devastation that they leave behind is that they do go for the well looked after lawns.
    The reapplication really depends on what type of spray you have used to kill them. Some sprays have a longer “shelf life” than others and the sand granulated based killers are different again. Have a look at your back label of the chemical you used and go from there. My rule of thumb is when you see eggs, throw a towel on the ground over night and see what if anything comes up. If you do see the nasty worms, hit it again.
    With the egg wiping, my best “Old Wives Advice” is to get some dishwashing liquid in warm water and add some tea tree oil or some eucalyptus oil to the water soapy water and wash down the areas. The moths don’t like the sticky feeling on their feet (or that’s what I have been told) and they are repealed by the smell. It is an old wife tale but it has worked on our sheds.
    Also keep an eye out on your neighbours lawn if they look like they have an infection hit your lawn again.
    Your Blue couch should come back and with the change of season approaching fertilize then with an organic based fertilizer. Top dressing may be the best way to go considering you may have small dead patches across your lawn. The nutrient rich soil will give the Blue something delicious to grow in. I like spreading the soil before rain as it can be a bit smelly and the rain washes all the smelly (but great for your lawn) parts down to the root system.
    Chat soon
    Hope all goes well

  11. Hi. I have had army grubs in our crop of millet. We have mulched it and ploughed it in. We spread chicken manure and ploughed that in before planting the oats which came up. Now the army grubs have eaten it. I was wondering how long before it is to cool for them as we would like to plant again for our winter feed, or have you any suggestions. We sprayed the area around the farm with Fortune 500 which killed the grubs in that area. Thank you I now it is a lawn but we need help with this.

  12. Thanks for getting back to me Sare. I will try your trick with the tea tree oil… they have reduced building their little cocoons. I wiped down yesterday, mind you had a few new ones there this morning, urgh (we had some rain last night). They seem to be “marking” by ceiling just by touching with their wings and flapping about, gggrrrr… I broomed the entire ceiling yesterday and it needs to be done again. The lawn is already looking better to me, after the little rain. Will keep on top of it and do the towel trick. We applied the Brunnings spray on lawn and grub destroyer. Thanks again.

  13. hi i have sprayed for lawn grubs cleaneed all the eaves but still have lots of moths at night what do i do now thanks ken

  14. Hi Margaret.
    Try Loresban for the grubs. that’s the best insecticide we have found. What do you need help with now? The lawn?
    If you have killed the grubs in your lawn, then try fertilizing the area with chicken manure or top dressing it with the beginning of autumn coming.
    Let me know if I can offer an more advice

  15. Ken, How close are you too and with your neighbours. Although you may have licked the problem at your place, your neighbors may not be as vidulant. Check around and maybe offer advice….

  16. Just found this site,great info here.
    Have read all the comments very informative.
    I live between Brisbane and the Gold Coast and noticed a lot of brown moths flying over my lawn at night.

    My question is..
    1. After spraying with an insecticide when would you spray again?
    I still seeing moths flying over the lawn after i sprayed a week later.


  17. I have just treated all the nasty lawn grubs with a powder that seems to be killing them. Do I need to do it again in one week’s time?

  18. Hi Kylie,
    Have a look not only at your lawn but around the neighbours as well as see if there are any signs. If you do, then I would sprinkle it out again.
    Hope it all works

  19. Hi Steve,
    Have a look at your spray info sheet and see if it recommended you give it another hit. The best time to spray is at dusk as this is when the bugs are most active. Loresband is awesome at dusk for knocking them dead! We always add a little bit of washing up detergent to make sure it is tacky and sticks to bugs.
    Watch out that the moths aren’t out laying new eggs around your house too. Wash all your eaves, windows, roofs, all damp out of the wind areas.
    So in answer to your question, yes I would spray again, just to be on the safe side, as spraying is contact based where as the sand granulated ones stay in the soil for longer. And I would definitely wash all the walls eaves, etc for the eggs that are going to be hatching out soon.
    Hope all goes well

  20. Hi could you tell me the mix i should use of chlorpyrifos 500ec for lawn army worm as i need to know how may mls per liter of water i need as it only tells me mls per ha cheers Scott

  21. Hi i sprayed with grub 500 and a heap of grubs come to surface does that mean they have died or will die

  22. It means they are going to die. haha. You have got those ones, but don’t forget to clean your eaves and windows to make sure no eggs have been laid. Check for new ones next week and maybe apply again.
    Chat soon Sare

  23. Hi, we use it at 5% per volume.
    Chat Soon

  24. when the cocoon hatches how does the “new born” get to to the lawn from the ceiling?

  25. The Larvae then descend from your ceiling with fine silk threads, kinda like a spider web thread. You can sometimes see them glisten in the morning in the dew. Then depending upon where you lawn is from where they land the larvae crawl to your lawn and start chowing down.

  26. Last spring we had an infestation of moths unlike we’ve never seen before! We were literally held hostage inside our homes – there were so many we couldn’t go outside & they covered every inch of the houses & outbuildings. The invasion started in late April & continued for 3 weeks. This year, I have noticed thousands of small holes in our lawn. Could this be moths again?!

  27. jade rose says:

    i have rabbits so will this be ok to use?

  28. It will depend on the grub control you use. Please make sure that you read the label really carefully before and after you apply so you can make sure that animals and kids are safe

  29. it is the start of june I live in n.s.w Australia in a coastal town. we still have army grub even after spraying it. it was new turf so they just loved it.was totally unprepared so they destroyed the whole it possible that the lawn we come back with mwinter here,

  30. Oh No! What a horrible thing to happen! Firstly make sure that you have got all the eggs from around your place, so it doesn’t happen again. The regrowth of your turf will depend on a couple of things. What type of grass it was (couches have a strong root base, and Palmetto Buffalo is very aggressive), how long the grass was down for (did it have time to establish at all?) and the how cold the winter is? We still are able to grow Turf in the winter at the farm and we are only 3 ks from the beach. Let me know if there is anything specific we can help you with by emailing us at
    hope all goes well
    Chat soon Sare

  31. I used cheap dish washing liquid. About half a cup in a large watering can. It helps to identify where the grubs are so you can treat only the affected areas. This method is to save wastage. the grass is unaffected by the treatment. When they come to the surface, birds will pick them up.
    After treatment, flush the lawn and fertilise with a good lawn feeder.

  32. Sare - Coastal Turf says:

    Great Idea Dennis! Love forward saving Ideas!

  33. Pest Control For Larder Beetles. Don’t overlook these deductions:
    . There arre roughly 5,000 different species that live throughout the world in
    most regions.

  34. Good advice but I was wondering if you have a eco friendly alternative to chemicals to get rid of the lawn grubs? I want them gone because they are destroying my lawn but would like a non toxic way to deal with them if it possible. Any advice is greatly appreciated. Cheers, Tony

  35. Sare - Coastal Turf says:

    HI Tony,
    Prevention is the best cure. Making sure your eaves and walls are clean of all eggs.
    Once you have them though, the only way I know to get rid of the nasties is with the chemical killer. I have seen people use chickens to eat them, but usually by this stage it is a little late.
    But check around and see what you can find. I’d be really interested in what you find.
    Chat Soon

  36. I every time emailed this website post page to all my associates, because if like to read it after that my friends will too.

  37. It’s fantastic that you are getting ideas from this post as well
    as from our discussion made here.

  38. sorry to harp on about army worm still but my question is this. There are no ‘fluffy’ looking cocoons anywhere around the house. I have not seen the red wasp that usually hovers over the lawn and I have not seen any dead worms, despite spraying my sadly dead lawn. What I do see when I water or spray is hundreds of baby moths leap frogging out of the grass roots. Is this still part of the army worm conspiracy



  39. Sare - Coastal Turf says:

    Yes Gary unfortunately it is…
    Get serious and intense. If you cannot kill them yourself call in a Lawn Man to a Turfman to help fix the problem

  40. Hi, I have santa Anna couch grass and I’m at the end of my teacher with lawn bugs. My grass looks horrific. I have followed all advice given but they come back worse. I think it’s black beetle. Any suggestions?

  41. Hi
    Have just used granula insecticide to kill African black beetle and grubs and army worm in my lawn! Had to wait for rain to do so as we are on level 3 water restrictions (buckets only between 6 and 8pm!). After 3 days of wet weather I have noticed moths flying out of grass this morning in large numbers and birds having a feast what do I do now! Very frustrating!

  42. Thanks for all this great information. I am surprised how quickly it has all happened. I first noticed the grubs a week ago, and used Eco grub killer which is based on eucalyptus and tea tree oil added to a watering can of water. This brought a lot to the surface and I thought we had solved the problem. Three days later I noticed many active, very busy grubs in the lawn so bought and applied the Scotts Lawn Builder. Again hundreds of grubs have come to the surface. Meanwhile all the couch parts of my lawn are dead and the buffalo sections, while still green are munched into and weak looking. This has happened in a 6 day period. Will this be enough? I have also notice, now with a thinner, dead lawn that I have small dark spiders and ants. Is there any more I can do to help the poor lawn??


  43. Hi I just returned from holidays and found the lawn grub in my lawn (2nd yr in a row). I have spent the last two nights spraying the lawn and have just applied the Scott’s lawn builder and grub killer. I now cannot see any grubs alive however have a heap of moths. I did not have them last night. Any suggestions.

  44. I must of picked up a couple of hundred dead and dying lawn builder and grub killer.
    The stuff definateley works well.
    The butcher birds are having a feast on the ones I miss or come to surface when they are hunting.
    Will eating any of the poisoned Beatles harm them and should I keep picking freshly dead ones up.

  45. Sare - Coastal Turf says:

    I would contact your local Couchy Couch consultant and get them in to spray your lawn. If the nasty little grubs get in bad plague like numbers, get in a professional to save your investment into your lawn!

  46. Hi, just found this site. Great information and describes what is happening to my lawn.i have lots of dead patch and cocoons eaves. I will hit it with surefire fortune 500. Ill let you no the outcome.

  47. Hi Dexter
    did it work with Fortune 500.
    If it worked what is the ratio you did with water?

  48. I Used Fortune 500 which is a very strong insecticide. At first my wife did not want to use it but relented when the lawn was getting hammered. It definately works but we have had to keep spraying to break the cycle. 5 ml to 5L was all we used. Be very careful with it as it is strong.

    I unloaded countless “grub destroyer” products from the local hardware and they did nothing. Fortune 500 will get the job done.

  49. Sare - Coastal Turf says:

    Hi Neil,
    Yes Fortune 500 works, but like you say it is a really strong chemical. If you are ever worried about using a chemical contact us and we can put you in contact with a Chemical Certificate holder who can spray your lawn with confidence.

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