Animals Digging Up Lawns

Written by Daniel Woodley. Fact checked by Paul Farley. Published to Blog on the 2nd October 2023.

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Yesterday, I woke up and opened my curtains to discover holes of various sizes dug into my lawn. I’m 100% sure they weren’t there yesterday, so what’s going on? Who is the culprit and what can I do about it?

As I’ve worked in the landscaping industry for many years, I actually knew the culprit – Chafer Grubs and possibly Leatherjacket Grubs too. 

These grubs hatch from pupas in the Autumn (Chafers sometimes in the Spring too) and start to devour grass roots. The Chafer Grub, in particular, is a delicacy of foxes, badgers and many other animals who will tear up the turf to get to them.

Birds also love them and will use their beaks to dig into the lawn, leaving smaller but more numerous holes.

Here are a couple of photos:

How to Diagnose Which Grub is Present

I’ve always found it easy to find out which grub is present, here are my two recommended methods:

1) Use a shovel to dig up squares of turf and look at the soil in the roots and just underneath, this is where the grubs reside during the Spring and Autumn.

2) A less invasive method I have used many times is to lay a dark tarpaulin or plastic sheet over a section of soaked lawn and in the morning, lift it. Any Chafer or Leatherjacket grubs will have made their way to the surface.

I prefer the tarp method for delicate lawns but for damaged, messy lawns, the shovel method is just as effective.

Above – Chafer Grub (from the Chafer Beetle)

Above – Leatherjackets (from the Crane Fly aka Daddy Longlegs)

Timing of Eradication Attempt

I know from my own experience that during the winter, the Chafer and Leatherjacket grubs will burrow deeper into the ground to stay away from harmful frosts and any treatment attempts will likely fail.

In early summer, the grubs turn into a pupa with a hard shell that the treatments won’t be able to penetrate.

In late summer, Crane Flys (Daddy Long Legs) hatch from the Leatherjacket pupas and Chafer Beetles hatch from the Chafer pupas, I have found that neither responds well to commercially available treatments.

Based on my experience, the best time to treat these pests is when they are in their grub form and are young – that’s in Autumn.

Some species of Chafer will hatch in the Spring so a second round of treatments should be applied as the temperature exceeds 12° in the Spring.

I have previously had good results by treating Chafer grubs both in the Autumn and the Spring.

Methods of Eradication

There are two methods that are widely accepted as being successful, I have had good results by deploying both but on every occasion, I have had to apply repeat treatments throughout Autumn and Spring to get the results.

I have never seen a Chafer or Leatherjacket infestation successfully treated by a single application or treatment.

Method 1 – Use the tarp method, as mentioned above. Heavily soak the lawn and lay a dark tarpaulin or plastic sheet and lift it the following morning. Some of the grubs will have migrated to the surface, where you can lift them off. This method works very well but is labour-intensive and needs to be repeated over several weeks, hence, some gardeners prefer method 2 – it’s not practical for gardeners to visit their customers’ gardens every day.

Method 2 – Introduce parasitic nematodes. These are microscopic worms that eat into the grubs and kill them. I’ve found that they are easy to introduce (just add to water) and they won’t harm other animals in the garden. Nematodes thrive in warm, wet soil and will die off quickly in cold, hot or dry conditions so they must be applied in the Spring or Autumn and the lawn must be kept soaked for up to two weeks after application.

Repeat Treatments

I’ve found that the best results are achieved by using both the Tarp and the Nematodes throughout Autumn – that means repeat treatments every couple of weeks until the temperature drops.

I’ve always applied a follow up Chafer treatment in the Spring as well.

Chemical/Pesticide Treatments

In the UK, there are no chemical or pesticide treatments on sale that treat Chafer or Leatherjacket grubs.

Any chemicals or pesticides would also kill beneficial worms and insects and their sale is restricted.

What Happens if The Grubs Aren’t Treated?

Both Chafers and Leatherjackets consume the soft roots of grass, and when left unchecked, I have seen lawns exhibit the following issues: 

Mild – patchy areas where the grass died, a few holes dug by predators.

Severe – the grass lifts easily as the roots are short, large patches of discoloured grass, the lawn looks weak and isn’t responding to water and fertilisers. Large and numerous holes caused by predators.

Very Severe – the grass has almost completely died as most of the roots have been devoured. The lawn is mostly dirt and weeds with few blades of grass. Large holes from previous predator visits.

I have seen cases where the only viable option was to top strip the lawn (or what was left of it) and leave it bare over winter to starve the grubs and re-seed or turf in the Spring. This method was effective but not everyone wants to spend a winter with no lawn.

Prevention

Most people aim to control the Chafer and Leatherjacket grub populations as they often migrate in from neighbouring gardens.

I’ve successfully treated both in the past but always recommend a twice-yearly treatment with nematodes as a preventative measure. If you see tell-tale signs they have returned in significant numbers, try the tarp method again as well.

Dethatching the lawn regularly can also help, as some will feed on soft decaying grass as well.

Other Animals That Dig Lawns

In addition to foxes, badgers, birds and other animals that dig for grubs, you may see lawn damage by the following animals:

• Cats – digging poop holes.
• Dogs – for comfort, to cool down, to hide something.
• Squirrels – to hide food.
• Moles – for habitat.

Summary

If you see animals digging holes in the lawn in Autumn, this is most likely predators looking for food, such as Chafer or Leatherjacket grubs.

The Tarp method is an excellent way to identify and lift the grubs but alone won’t be enough to eradicate them.

Nematodes are effective but the gardener will need to keep the lawn soaked for up to two weeks after application and further treatments will be needed.

A Note From Our Reviewer

Here at DIY Gardening, we frequently ask experts to review our statements and provide additional insights for our readers.

Here’s what Paul Farley had to say about Chafer and Leatherjacket grubs:

The regulations in the UK and EU regarding pest control products are far stricter than those in the US. All of the products on sale in the UK are organic and the user will need to use them more frequently to achieve the same results.