Are chafer grubs eating your lawn? 3 tell-tale signs

Chafer grubs are about as unpleasant as they sound. Left to their own devices, they can wreak havoc on a lawn – so it’s crucial that you know how to get rid of chafer grubs.

First, though, you’ll need to know how to spot them. Several common lawn diseases in the UK can make grass look just as unhealthy, but there are a few tell-tale signs that chafer grubs are the culprits behind a struggling lawn. They feed on the grass roots, which weakens and even kills the grass.

‘Soon it will be the optimal time to treat chafer grubs,’ says GreenThumb’s technical manager, Alasdair Boyes. ‘If left untreated, these pests can cause significant damage to your lawn.’

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Here’s how to spot a chafer grub problem – and the best ways to get rid of them.

What you’ll need

How to tell if chafer grubs are damaging your lawn

1. Brown or yellow patches

Before you learn how to get rid of chafer grubs in your lawn, you’ll need to make sure they’re actually the problem.

‘Chafer grub damage becomes quite easy to spot once you know what you’re looking for,’ says Cheryl Harper, managing director at Greensleeves Lawn Care. ‘One of the first signs is patches of grass starting to turn yellow or brown, particularly during the warmer months when the grubs are most active.’

There are several other reasons why a lawn might be turning yellow, though – so it’s best to look at the other signs, too…

2. Spongy underfoot

According to Cheryl, a lawn with a chafer grub problem will often feel soft or spongy underfoot.

‘In more advanced cases, the turf can actually lift away very easily – almost like a loose carpet,’ she explains. ‘This happens because the grubs are feeding on the roots beneath the surface, weakening the grass so it can no longer anchor itself properly.’

You can sometimes even see the chafer grubs underneath the surface of the turf. They have C-shaped white bodies with three pairs of legs by their light brown heads. If you spot longer brown grubs, it’s more likely that leatherjackets are infesting your lawn.

3. Wildlife behaviour

Wildlife can also give chafer grubs away. If you notice more birds pecking at your lawn than usual, there’s a good chance the grubs are to blame.

‘You may also notice increased activity from birds or other wildlife, as they dig into the lawn to feed on the grubs,’ says Cheryl. ‘While this can make the damage look worse, it’s often a helpful clue as to what’s going on beneath the surface.

‘When you see several of these signs together, it’s usually a strong indication that chafer grubs are the cause.’

So, how do you get rid of chafer grubs in a lawn, then?

How to get rid of chafer grubs in a lawn

It isn’t a case of removing the grubs by hand – you’ll often need a full treatment to completely banish the pests. Luckily, that treatment doesn’t have to be chemical.

‘The most effective way to deal with chafer grubs is by using a biological control treatment,’ says Cheryl. ‘This involves applying nematodes, which are microscopic organisms that naturally target the grubs without harming other plants or wildlife.’

You can buy Gardening Naturally Chafer Grub Nematodes from Amazon.

‘Once applied, the nematodes are watered into the lawn where they move through the soil and infect the chafer grubs with a bacteria that stops them feeding and ultimately kills them,’ Cheryl explains. ‘It’s a targeted approach that works with nature, rather than against it.’

Cheryl says timing is really important if you’ll be using nematodes on your lawn, as they need warm soil to survive. July to September is usually the ideal window – the grubs are usually more active towards the surface then, too.

After that, you’ll need to follow up with a few more lawn care steps.

‘Damaged areas can be cleared and overseeded to encourage new growth, while ongoing care – such as mowing at the right height (around 2.5-4 cm during the growing season, slightly longer in hot or dry conditions) and regular watering – will support a stronger, healthier lawn over time,’ says Cheryl.

If you suspect chafer grubs are eating your lawn, it’s best to be swift about treatment.