Black Beetles

Author: Stefan Palm   Date Posted: 21 October 2020 

Do you have dead spots in your lawn? Now is about the time of year when black beetles and their larvae are active in lawns. They have the potential to damage lawns so if your lawn is patchy, they could be to blame.

The biggest tell-tale sign that most people identify with beetle damage is dead and dying patches in their lawn. While this can be the case, dead and dying patches in lawns are the tell-tale sign of most lawn problems so it’s not a conclusion that I would jump to without further investigation. Dead and dying patches can be a symptom of disease, non-wetting soil, maintenance issues, shade, turf mites, the list goes on so it’s important to properly identify the issue before you rush out and buy some beetle killer.

I have to say that after consulting on thousands of lawn problems over the years, that while black beetles often get the blame for dead and dying patches, they are rarely the culprits. In any case, it’s not the adult beetle that does the damage to your lawn – it’s their larvae. The adult beetle might eat a bit of your lawn, but the real damage is comes by the eggs they lay in the soil. As the eggs hatch into larvae, they eat your lawn roots till they mature into adults at which point they dig out and fly away.

Having said all of that, there are many instances where beetles are to blame and for those times, you’ll need an action plan to get rid of them.

How can you tell if you have beetles?

The simplest way is to get a trowel or spade and dig a 300mm x 300mm core sample from one of the affected areas in your lawn. Two of the prime active times for beetles is October and March. This is when eggs hatch and the cycle starts. Look for beetle larvae which can range in size from a couple of mm long to 6cm long, depending on the type of beetle and how mature they are.

If you can't find any larvae in the core sample you take out, then it’s safe to say the problem isn't beetles. If you find several larvae in the sample, I’d be looking to start a treatment program.

How do you control them?

Preventative treatment is the best way to keep on top of pests like black beetle larvae in your lawn. There are several things that you can do to prevent serious damage.

Regular monitoring of your lawn will ensure that a major infestation doesn’t appear overnight.  Well cared-for lawns are more likely to resist, and recover from beetle larvae attack than neglected ones - healthy lawns can actually sustain a reasonable population of beetle larvae without the lawn showing any symptoms!

If your lawn does become infested, chemical control is the most effective treatment method.  Look for chemicals that contain imidacloprid or acelepryn . These sorts of chemicals will last in the soil for 3 or more months and specifically target the larvae. Any new larvae that hatch inside that window will die too. Look for Yates Complete insect control or Yates grub kill and protect as both these products offer long term control. They also control other lawn beetle pests including argentine stem weevil larvae, billbug larvae; and lawn caterpillar pests including, armyworm, sod webworm, and black cutworm.  Applying these chemicals in early to mid Spring and again in early to mid Autumn will prevent infestations from occuring. 

What if it isn't beetles?

If you notice that the core sample that you dug out does not contain any beetles or larvae, there is a fair chance that there are other issues at play causing the dead and dying patches. If you have issues in your lawn that can’t get to the bottom of, give us a call on 8298 0555 or leave a comment on this post. We’d love to help you get your lawn back to green.


Comments (2)

Buffalo Sapphire dieback

By: on 29 March 2019
About a year ago, I laid Sapphire instant turf partially under trees and in full sun in my rear yard. All the prep was done and drip irrigation installed and working. Some areas never grew or slowly died back, other areas did very well. Been mowed twice in 18 months. Over that time I have treated with light dose of seasol, liquid gypsum to improve drainage although no pooling, put on a sprinkler as drippers could be blocked, alternated watering between long infrequent monthly and short frequent weekly to twice weekly, dosed with imidacloprid, applied light fertiliser, aerated and top-dressed but to no avail nada nothing no improvement or recovery. I've pulled the few weeds by hand and haven't used weedicides or pesticides. A friend told me that Sapphire is has no resistance to a fungus and the industry knows this ? Can you confirm and if so what do you recommend? What do think about phosphonic acid - potassium phosphonate?

Paul Munns Instant Lawn Response
Hey Alan, Thanks for your comments on Sapphire Buffalo. You obviously have some issues to resolve - a lawn that has only been mowed twice in 18 months is not a healthy lawn. Your response to the problem is to try an array of different remedies which I understand to date has had no impact. This is because the cause of the problem has not been understood and therefore has not been addressed. I know it can be frustrating trying to get to the bottom of specific lawn issues, especially when you are relying on internet articles and other more generic advice from friends. The only way to solve your issue to understand the exact nature of the problem. Otherwise you will continue to spend money on it with no result. For example, if your problems are not related to pH issues or a phosphorous deficiency, then the application of phosphonic acid won't solve the problem. Give me a call on 08 8298 0555 if you'd like to have a chat about it. Regards, Stefan

Dead lawn

By: on 18 March 2018
I applied SeaSol to some browned off patches on my lawn and the sections that died were not the ones I treated. When some of the lawn died off overnight I airated this section and applied Seasol. The lawn seems to be recovering quiet well. The problem might be solved. However I will do the things mentioned in your article, dig a hole, etc and take your advice. Thank you for your help. It was more than l thought I would find on the Internet.

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