Black Beetles

Author: Stefan Palm   Date Posted: 19 February 2019 

Do you have dead spots in your lawn? – It could back beetles but could it be something else too….

Often people come into our shop or call over the phone to talk about the dead spots in their lawn and ask us how we can help them solve the problem.  More often than not, black beetles get the blame and some of the time they are the culprits… but most of the time they are not the leading cause of dead or dying patches in lawns.

I want to be really clear about a common misunderstanding when it comes to diagnosing the cause of dead spots in lawns. If you have an otherwise healthy lawn and notice dead or dying patches starting to appear, the issue is rarely caused by beetles or their larvae. It is possible but its not common. 

In any case, it’s not the adult beetle that does the damage in your lawn – it’s their larvae. The adult beetle might eat a bit of your lawn, but the real damage they cause is the eggs they lay in the soil. As the eggs hatch, the larvae eat your lawn roots till they mature into adults at which point they dig out and fly away. One beetle larvae has the potential to eat the lawn roots from area the size of a 50c coin. To get large patches dying off in your lawn, you would expect to see hundeds of larvae moving around in the soil beneath the lawn. 

How can you tell if you have beetles?

The simplest way is to get a trowel and dig a core sample from one of the effected areas in your lawn. Two of the prime active times for beetles is October and March. If you can't find any larvae in the core sample you take out during in these times, then its safe to say the problem isn't beetles. Even if you find one or two larvae then I still wouldnt celebrate solving the issue.  You'd need to an infestation of larvae to conclude that beetles were in fact the cause. 

If you do find large amounts of larvae, traditional beetle killer granules won't solve the problem. They target the adult and not the larvae which is almost a complete waste of time.  What you need to use are chemicals that contain Imidacloprid. These sorts of chemicals will last in the soil for 3 months and specifically target the larvae. Any new larvae that hatch in that 3 month window will die too. Better yet, get your hands on a product called Yates Complete insect control. It has imidacloprid and cyfluthrin. Cyfluthrin targets the adults so together you kill the adult and the larvae. Problem solved. 

What if it isn't beetles?

If you notice that the core sample that you dug out is dry and the rootzone is short, either you're not watering enough or its an issue called Dry Patch. Dry patch is where random sections of your soil become water repellant and repel water instead of absorbing it. This is a very common issue. Most people dismiss this, thinking that it cannot be a water related issue because they water often, for long periods. The ironic thing with dry patch is applying more water won't solve the problem. The more water you apply, the more it repels leaving those patches in a constant state of dry - hence why you're holding a dry core sample. 

The way to solve water repellancy in soil is to apply a liquid wetting agent. Liquid wetting agents solve non wetting soil issue and ensure that soils wet evenly. They also enable the water to travel down deep into the soil. Wetting agents don't last long and have to be applied ever 8-10 weeks during the warmer months. You'll be amazed at the difference wetting agent can make in a patchy lawn environment. 

Other issues can include disease and mites ( 

If you have dead or dying patches in your lawn that you 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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