Are Lawn Grubs Bad?



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Every year many lawns fall foul to Grub problems.  Are they really all that bad for your lawn?  What are the answers, what can you do?  Here I help you figure things out.

are lawn grubs bad

How to get grubs out of your lawn

It’s just nature at the end of the day, but unfortunately, we seem to be getting more and more instances of them, year on year.  I’ve been treating grubs for over 15 years, so it’s not just a recent thing.

However, people are becoming more and more aware.  They usually ask about ways to kill off the grubs.  Over in the states, they still have effective total kill pesticides, but here in the UK these are all banned, and we are only left with “natural” methods with no foolproof way to success.

Over in France their chemical control measures are far stricter with outright bans of pesticides and weedkillers, so they are losing the fight against weeds and pests from a chemical advantage point.

So 15 years ago I could apply a powder pesticide wearing a face mask and it would kill outright all grubs within hours.  Such was the power of this that it got banned amid fears of possibly affecting bee populations.

Thankfully there are a few things that can help, plus I now have a number of ways we can control the numbers.

Are lawn grubs really bad?

Like I said, a few are “ok”.  Many lawns will have one or two and your lawn can cope if it’s being well maintained.  The problem begins when numbers increase, and as a result you will find more foraging activity from birds and badgers looking for their next meal.  If the turf is in really poor condition and the roots have been well eaten, the birds can literally pick the grass up and turn it over like a piece of carpet.

Where do grubs come from?

They start out in life as insects.

In the Uk, there are 2 main types of grub infestations we see in a lawn.  A Chafer grub and a leatherjacket grub.

Chafer grubs are curled up “C” shaped White or creamy coloured grubs with Orange heads.  Leatherjacket grubs are usually straight long grubs of grey or Black colour.

The Chafer grub comes from the Chafer beetle (there are a few variations of the Chafer beetle as well).  These are sometimes known as the May beetle as you often see them around may time flying around looking for mates.  These beetles have a Copper coloured back.  You have to be fast to catch them, as the whole show is usually over within a week or two and then the eggs are laid in the ground under the turf.

The Leatherjacket grub is the larvae/grub from the Crane fly (daddy long legs).  You typically see them flying around in Autumn looking for mates then they lay their eggs in the soil that hatch over Winter and into Spring.

Usually around 2 weeks after egg-laying, they hatch and the tiny larvae emerge and begin to feed on the roots of your turf.  Ready for a feast!

How to get rid of grubs naturally

Well, let’s start out by stating a few things here.  A good STRONG healthy thick grass plant can often withstand larger numbers of grubs within its roots.  A poor weak lawn will always suffer first.

So your main aim is to try and produce a super healthy thick lawn which is watered well and regular and is never cut too short.  You should also mow at least weekly and try to maintain a length of approx 2 to 3 inches.

Aerating regular and applying suitable root development products can mean stronger deeper rooting system.

Use nematodes

You can buy leatherjacket OR chafer nematodes online (only at the right time of the year) which can be effective in reducing the number of grubs.  These have to be watered in really well and watered daily for 2 weeks to allow the microscopic organisms to swim around, seek out the grubs, enter inside them and release a poison which stops them from feeding and they die.

Use grub traps / lures

You can purchase a lure that you hang in a nearby small tree or shrub (the usual places where mating occurs between beetles).  These attract the males by the pheromone attractant and they get trapped.  This ultimately means that you end up with fewer females having mated, and as a result of this, fewer eggs laid.  Pop these out every Spring / April time to reduce numbers.

Homemade grub killer

So if you want to try some things yourself without resorting to chemicals or having to go out and buy expensive products I am going to share a few things that might just blow your mind (and if you’ve read all the way to here well done as these are golden nuggets!)

  • Alcohol and garlic.  Go grab some cheap booze and a tube of garlic powder.  It can be the slops from a bar’s drip trays or cheap cans of lager or cider.  pop the alcohol and garlic in a watering can and top up with water.  Water the potion into the lawn and water it in.  Give it a few days and dig around to inspect.  Hopefully, they will have died and turned a Grey colour and won’t be feeding.
  • Black plastic sheet.  lay one on the lawn overnight.  The next morning take it off and you will find a number of grubs that have come up to the surface.  leave them for the birds to enjoy, or pick them off and discard.
  • Homemade lure.  For a beetle lure to be effective, you first need to put it out at the right time (spring for Chafer beetles, and Autumn for crane fly).  The height of the position of the lure is also important. Around 1 to 2 metres is perfect.  Place some banana pieces and alcohol in the bottom of a yoghurt pot.  Grubs love the banana but also get affected by the alcohol.  Suspend it from a string in a tree and see how many you get each day!  If you can get a slightly larger yoghurt pot over the top so it is harder for them to escape.

Will your grub damaged lawn grow back?

Yes and no.  It most certainly can grow back in many situations but with the right methods.  Sometimes their roots have been eaten and the grass has simply died off.  Many people see their Brown coloured lawns and assume that it is just the sunlight drying it out.  When in fact what has happened is grubs have eaten the roots and it is slowly dying off.

So YES if you catch it quickly enough you can get the lawn to grow back following grub damage.  The way to achieve this is by watering REALLY well and applying a fertilizer that is heavier in Phosphorous and Potassium (both of which aid root development).   Look at the N P K numbers on your fertilizer and aim for something where the last 2 numbers (P and K are larger than the Nitrogen).

I almost always go for a wetting agent at the same time.

If you imagine a roll of fresh new turf.  The roots have been sliced off by the turf lifting machines.  You lay the turf down and water well for several weeks.  Well, with grub damaged turf keep watering really well to keep trying to force new root growth and you might just be able to push through the issues.

Is it too late to treat for grubs?

Naturally, timings are very important to success when trying to kill or control grub numbers.

When considering Nematode use, the best time to apply is 2 to 3 weeks AFTER the eggs have been laid.  For this, you need to be really vigilant in knowing when this happens to know when to apply.  However, if you simply opt for May to June and apply Chafer Nematodes you will usually have a moderate degree of success.  Around October would be a fairly good time to treat for the leatherjacket grubs.

If you are going to try the plastic sheet method this can be done any time.  Lay it down overnight and see what has come up the next morning.

If you want to try the alcohol and garlic method, again any time is fine to try.  Just bear in mind that during the coldest part of Winter most grubs retreat deeper underground and return once temperatures pick up.

Any questions?  Feel free to drop me a comment below 🙂

Shaun Baird

By: Shaun Baird Owning a running a professional lawn care company offline, Shaun has brought his knowledge and tips to this website. If you ever wanted someone to help you, Shaun would be your man. He has spent most of his life helping others, often without realising, and used this passion to drive the 10 Warriors brand forward. His knowledge of lawn care and creating stunning lawns has been brought to the 10 Warriors brand. This unnerving dedication to always help people has become the focus for Shaun to dedicate his efforts to helping a wider community.

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