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Lawn Grub Detection and Control

Lawn Grub Detection and Control

Lawn Grub in the Domestic Lawn

Green Grass

So you have spent weeks preparing and caring for your lawn, and it is paying off! It has finally become beautifully lush and green, and is like a carpet! A little brown patch appears… you think maybe it just needs a bit of water, or maybe a little bit of fertiliser burn has occurred. No panic, put the sprinkler out for 20 minutes or so and she’ll be right!Over the next few days the brown patch becomes bigger and bigger and is spreading across your lawn! Every green keepers worst nightmare, lawn grub! Now, in Queensland there are a couple of different types worm we commonly refer to as lawn grub, they are White Curl Grub and Army Worm.

White Curl Grub

The first lawn grub is actually scarab beetle larvae which is the juvenile stage of lawn beetle. So really, white curl grub is incorrectly referred to as a ‘lawn grub’ or ‘witchety grub’. These white curl grubs are a serious lawn pest and the signs of infestation are easily confused with other pests, diseases and disorders in turf. The end result of a white curl grub infestation is basically, yellowing to browning and ultimate death. White curl grub will eat away at the root system of turf which in turn causes death, with a serious infestation, you are often able to roll your turf up as the root system is completely destroyed!

White Curl Grub

White Curl Grub

Every lawn in Queensland at this precise time will have some white curl grub present and an infestation is generally regarded as a problem when there are 25 of more grubs existing per square meter. If less, a normal and healthy lawn with seasonal growth will sustain any damage caused. However, other external influences may likely exacerbate the problem, such as heat or drought conditions.If you have concerns, the best way to check for lawn grub is to grab a hessian bag or piece of old carpet and lay it on the grass in the late afternoon. Wet the bag or carpet thoroughly and leave overnight. The following morning the lawn grub will have been drawn to the surface, and an assessment can be made.

Army Worm

Army Worm

Army Worm

The second lawn grub critter is known as Army Worm. The adult lawn armyworm takes the form of a greyish-brown moth with a wing span of 35 to 40 mm. Damage from these guys differ slightly from the white curl grub, as they work similar to that of other caterpillars, eating away at the leaves of the turf and damage is often seen as a clear line of dying grass marching across your yard. Often starting closest to the house near external light sources, which attract the adult moth. Determining if you have an Army Worm problem is the same process as above with the white curl grubs. However, be aware that if you have had some reasonable damage occur you will need to be smart with your test placement. Obviously, the grubs will have already moved on from the ‘dead patch’ and will now be working in the green lawn.

Prevention and Treatment

Now if your thinking they won’t get you because you care for your lawn and it is the healthiest in the street… I have news for you! These annoying little guys aren’t interested in your neighbours unsightly mess of a yard. The lawn grub have champagne taste, and won’t settle for the sparkling wine! So unfortunately, the house with the nicest lawn is generally who gets hit the hardest!

Prevention is the key to avoid lawn grub! Unfortunately, most commercially available pesticide are designed to treat an existing problem of lawn grub, rather than prevent it from occurring. Although some of the granular mixes can be present for a little while after application, so will inadvertently prevent… for a short time at least! It’s the old adage, what came first? The chicken or the egg? Well, in this case, the moth! The first place to start is ensuring your eaves, house and fences are all free of moth nests. These range in appearance but mostly look like little cotton-like cocoons. The best attack is with a hose and a broom. This is by no means a guarantee, but at least you are limiting the amount of moths activity around your property.

Lawn Grub TreatmentsNow the most effective treatment for an existing infestation of lawn grub is unfortunately a chemical approach. Chlorpyrifos seems to be one of the most effective treatments and can be found in both a liquid concentrate for spaying and a granular form to be sprinkled and water in. Be extra careful with these forms as they can also be lethal for other animals that may come in contact, including children! The best approach is to treat late afternoon when birds are less active. The birds are attracted the wriggly (and dying) grubs which come to the surface of the lawn after treatment. The most important thing to remember when using ANY chemical type control, is to always read the label and apply at the recommending rates. It is important when treating an infestation to break the lifecycle. Treatment is recommended over a 2 week period – once on the first day, again on day 7 and the again on day 11. This breaks the cycle of cocoon – moth – egg – grub – cocoon… etc.

As a little bonus for this treatment, the Active Constituent of Chlorpyrifos is often also present in many commercially used products for treating Ant and other insect activity. So while you get the benefit of ridding your beautiful lawn of those pesky grubs, you should also see reduced numbers of Ants, lawn Beetle, African Black Beetles, Cockroaches and Spiders!

A natural approach generally relies upon carnivorous birds. There are a number of methods including flooding with water, and also soapy water, which will encourage the lawn grub to the surface, where they will hopefully be picked off by such birds. As you can imagine, this method can yield some rather sketchy results!

Good luck and remember to keep an eye on your Lawn!

November 19th, 2012|Tags: , |10 Comments

10 Comments

  1. Valerie Shaw May 12, 2016 at 8:12 am - Reply

    Does bifenthin work as well as clorpirifos for lawn grub in qld?

    • CLSOnline May 29, 2016 at 9:38 pm - Reply

      Hi Valerie,

      Bifenthrin is now probably the most common ingredient in many lawn grub control products. Chlorpyrifos is becoming harder to find in retail products as it considered a more dangerous chemical when not used correctly. It is safe when used to manufacturer’s recommendations and guidelines. It is still probably the most effective, but Bifenthrin is still an effective product. Once again, follow the manufacturer’s recommendations and guidelines and remember to treat multiple times.

  2. Alison October 12, 2016 at 6:33 pm - Reply

    Just seen my first grub of the season after a horror year last year! Are granular or liquid more effective? Do you know if most gardening services will treat for me / any commercial garden pest control? I rarely have time to get out onto the lawn without my kids running all over the chemicals.

    • CLSOnline November 9, 2016 at 8:44 am - Reply

      I would say liquid treatments are more effective. Granular treatments then need to be watered in regardless and you risk washing it away rather than dissolving in place.

  3. Sandy Sweeney January 23, 2017 at 2:36 pm - Reply

    how long after applying chlorpyrifos dingo / fortune 500 (hose on) can I deep water with irrigation After 5 years I still have this grub problem and often apply weekly when I see a disturbance or a magpie!

    • CLSOnline January 24, 2017 at 9:54 am - Reply

      Hi Sandy,

      I would allow 1-2 days for the grub killer to do its job.

      When you say you see disturbance, what are you referring to? Magpie’s are not always the best indicator of a pest infestation and treating once a week does seem like overkill. The lifecycle of most lawn pests should be broken in most cases by one treatment (maybe 2) in 2 weeks and should be effective for a number of weeks if not months after. The products you have mentioned are extremely effective and I would be surprised if you’re applying it correctly you would continue to have issues as regularly as weekly. If you’re suspicious of lawn grub, place a towel or hessian bag on the lawn in the early evening and flood the area. As the sun is coming up the next day, check under the towel to see if there are any live grubs. Most lawns will have some white curl grub present, and nature usually takes care of itself. It is when an infestation gets out of hand that the lawn can suffer. Perfect conditions like warm nights, plenty of rain or water and humid conditions encourage infestations and this is when you need to be most diligent.

      Treat your lawn at around 5PM to the recommended application rate for the product and water in lightly. Do this again on the 7th day and then again on the 11th day. This should break the grub cycle. Further, keep your house, facias, gutters, eaves etc clean and regularly hose down or broom off any moth eggs present (they look like light brown soft cocoons) to limit the chance of new grubs coming to feast.

      I hope that helps.

  4. Alex February 3, 2017 at 8:25 pm - Reply

    Is the hovex product ‘ultra-lo-odour-termite-insecticide-concentrate’ a suitable treatment for lawn grub?
    It doesn’t specify on the data sheet but it’s active ingredient is bifenthrin..if so at what rate should I apply per m2 of lawn and at what mix ratio?

    • CLSOnline February 6, 2017 at 11:54 am - Reply

      Hi Alex, we would always recommend using a product specifically formulated for the treatment of grubs. That being said, bifenthrin is a recommended chemical for that purpose. Some quick research gave me the concentration of 100g of bifenthrin per litre for that product. Other products specifically marketed for the control of lawn grub with the same active ingredients have a lower concentration (i.e. 80 g/L). Insecticides are poisons, and it is extremely important to apply poisons at the recommend rate for safe application. As this product is not specifically designed for the purpose you intend to use it for, you will need to do some research into a safe application rate. Bifenthrin is regularly applied in a granulated form for grub control, which makes it difficult to make a recommendation of application rate.

      Perhaps drop into your local store, or where you purchased the product from to see if there is a bifenthrin product in a liquid form specifically for grub treatment you could grab the application rate from. Remember, you may need to make some adjustments to the rate due to the concentration of the product you have.

  5. Kristy February 23, 2017 at 2:09 pm - Reply

    We are coming in to Centenary Landscaping on Saturday for new soil and turf as our old turf was destroyed by army worms. We have used Richgro Grub Killa after we ripped up all the old turf and I have not see any around yet but they don’t have anymore grass to attack. After we lay the new turf, how should we go about keeping them out of it? is it safe to put grub killer after laying new turf? also we have a little dog so what should we do about keeping her safe when using these products? Want to make sure we don’t let it happen again. Any advise would be great!

    • CLSOnline February 23, 2017 at 2:47 pm - Reply

      Hi Kristy,

      You shouldn’t get any worms after treating if you have removed the old turf. Armyworm feasts on the leaf, which is now gone. You might have seen some white curl grubs or perhaps their adult form being a shiny black beetle if they were present. Regular lawn grub killer would have taken care of those. With regards to prevention methods, unfortunately, there are not too many options. Pesticides are designed to come in contact with the pest and generally do not remain present long after application at the concentrations recommended. You could regularly treat say once a month from August through to March and be vigilant in between. But that relies on a bit of luck your application was applied at a suitable time.

      One of the best ways is to look for early signs such as moths at night and wasps hovering over your lawn during the day. Also, keep your house and eaves clean and free of any moth egg nests (small light brown fluffy cocoons). Hose them down and brush them off with a broom. Treat your lawn as soon as you see any sign at least twice over a 10-14 day period.

      It is fine to treat a new lawn with grub killer. In fact, in the current summer conditions, new lawns with plenty of water applied are quite susceptible. With regards to animals and children, please check the label of any chemical product you use. When applied at the correct application rate there will be some guidelines for how long to keep off the lawn. Usually a day or 2.

      I hope that helps!

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