How to Get Rid of Chafer Grubs and Leatherjackets in Your Lawn

There are few things more disheartening for a keen gardener than walking out one crisp autumn morning to find your once-immaculate lawn looking like it's been ploughed up overnight. Turf peeled back in ragged flaps, muddy divots scattered across the grass, and a suspicious gathering of crows, magpies and rooks pecking away with unseemly enthusiasm. If this sounds familiar, I've got some good news and some bad news. The bad news is you almost certainly have a grub problem beneath the surface. The good news is that it's genuinely fixable — and you can do it without dousing your garden in harsh chemicals.

I've spent a good few seasons wrestling with both of the usual culprits, and over that time I've come to appreciate just how much difference the right treatment at the right time makes. This guide is my honest, practical walk-through of how to identify whether you're dealing with chafer grubs or leatherjackets, and how to treat them using biological nematodes — the microscopic, living pest controllers that have quietly become the go-to solution for lawn lovers who'd rather work with nature than against it.

The Telltale Signs: Why Your Lawn Looks Like a Battlefield

Before you spend a penny on any treatment, you need to be absolutely certain what you're up against. The single most common mistake I see people make is treating for the wrong pest at the wrong time — and because these are seasonal, living treatments, getting the identification wrong means wasting both money and a precious application window you won't get back for months.

The most dramatic symptom is the secondary damage. Birds — particularly crows, magpies, rooks, jackdaws and starlings — absolutely adore both grubs and leatherjackets. They'll happily tear up great sheets of turf to get at the protein-rich larvae beneath, and it's this bird activity that often does far more visible harm than the grubs themselves. Badgers and foxes join the party too, digging conical holes across the lawn at night. If you're finding your grass rolled back like a carpet, the grubs underneath are the real problem, and the wildlife is merely the messenger.

The other classic symptom is patchy, yellowing turf that feels spongy underfoot and lifts away easily because the roots have been chewed through. A healthy lawn is firmly anchored; a grub-infested one comes up in your hand like a loose rug.

Chafer Grubs vs Leatherjackets: Know Your Enemy

Peel back a suspicious patch of turf and take a proper look at what's wriggling underneath. This is where you make your diagnosis.

Chafer grubs are the larvae of chafer beetles. They're fat, creamy-white, C-shaped creatures with a distinct light-brown head and three pairs of little legs near that head. When you place one on a flat surface, it will characteristically curl into that comma or 'C' shape. They're plump and soft-bodied, and larger specimens can be a good couple of centimetres long.

Leatherjackets, by contrast, are the larvae of crane flies — the daddy-long-legs that bumble around your windows in late summer. They look completely different: greyish-brown, legless, tube-like grubs with a tough, leathery skin (hence the name). There's no obvious head and no legs to speak of. If it looks like a wriggling brown-grey sausage with no distinct features, you're looking at a leatherjacket.

Why I Reach for Nematodes First

If you've been gardening for any length of time, you'll remember when the answer to any lawn pest was a bag of chemical insecticide. Those days are largely behind us in the UK — a great many of the old products have been withdrawn, and for domestic gardeners the practical, effective and genuinely satisfying answer now is biological control using nematodes.

Nematodes are microscopic worms that occur naturally in soil. The specific species used in lawn treatments are entirely harmless to people, pets, wildlife and beneficial insects like bees, worms and ladybirds. What they are decidedly not harmless to is the grub or leatherjacket they're bred to hunt. It's a wonderfully elegant, targeted bit of biology, and once you've seen it work you rarely look back.

How the Nematodes Actually Work

The mechanism is genuinely fascinating. For chafer grubs, the treatment uses Heterorhabditis bacteriophora — a living microscopic worm that seeks out the chafer grubs, penetrates them, and infects them with a bacteria which stops them feeding. The grubs then quickly die. The clever part is that the nematode then leaves the dead grub and goes off to seek out another one to infect, so a single application keeps working its way through the population.

Leatherjackets are tackled by a different species, Steinernema feltiae. These nematodes seek out the leatherjackets and attack the pest by entering through natural body openings. Once inside, they release bacteria that stops the pest from feeding, quickly killing it. The nematodes then reproduce inside the dead pest and release a new generation of hungry infective nematodes, which disperse and search out further prey. It's essentially a self-perpetuating hunting party — and it all happens invisibly beneath your feet.

Timing Is Everything: When to Apply

I cannot stress this enough — with nematodes, timing is the whole ball game. Apply them at the wrong moment and you might as well have poured your money down the drain. These are living creatures with specific needs, and they only work when two conditions are met: the soil is warm enough for them to be active, and the target pests are present, hatched, and feeding close to the surface where the nematodes can reach them.

Chafer Grub Timing

For chafer grubs, apply when the soil temperature is above 12°C, ideally from July to October. The very best results come from an application in September or October, when the chafer grubs are newly hatched, small, and vulnerable, and when the soil temperature is right around that 12°C mark. Younger grubs are far easier to kill than the big, tough, well-established ones you'll find in spring, which is why the autumn window is so valuable.

Leatherjacket Timing

Leatherjackets have a slightly different rhythm. The soil needs to be above 10°C for application, and they're best treated when the pests are newly hatched and feeding close to the surface — normally in autumn. In practice, there are two windows: from mid-April through to mid-May (applied at double strength, because the leatherjackets are larger and hardier by then), or from early September through to the end of October at the regular dose. That autumn slot, again, is the sweet spot, hitting the freshly hatched larvae before they've done their worst.

The Products: What's Actually Available

The nematode market in the UK is well established, and you'll find several trusted names selling essentially the same living organisms in various pack sizes. The key thing to understand is that you're buying a specific species matched to a specific pest — the branding matters far less than choosing the correct nematode and the correct quantity for your lawn's size.

For Chafer Grubs

Popular options include the Green Gardener Chafer Grub Killer, which contains Heterorhabditis bacteriophora, along with Nemasys G Chafer Grub Killer and the Nemasys Biological Garden Chafer Grub Killer. There's also the DragonFli Chafer Grub Killer, which comes in a 100 square metre pack containing 50 million nematodes. Whichever brand you land on, the underlying organism and the treatment approach are the same.

For Leatherjackets

The Nemasys Leatherjacket Killer contains Steinernema feltiae, and there's an excellent range of pack sizes from Dragonfli that lets you match the treatment precisely to your lawn: 25 million nematodes for 50m², 50 million for 100m², 250 million for 500m², and a hefty 500 million for larger lawns of 1000m². That range of sizes is genuinely useful — there's no sense buying a giant pack for a modest back garden, since these are perishable, living products you can't stockpile.

The Combination Option

If you've done your identification and you've genuinely got both pests — which is more common than you might think — there's a Lawn Pest Pack that contains both the Leatherjacket Nematodes and the Green Gardener Chafer Grub Killer, allowing you to treat both problems at the same time. Given that both treatments share an autumn application window, this is a sensible, tidy solution for a lawn under siege on two fronts.

Storage and Shelf Life: Handle With Care

Here's the thing that catches out first-time nematode users, and it caught me out too: these are living products with a short shelf life. Treat them like fresh food, not like a bottle of weedkiller that'll sit in the shed for years.

As soon as your delivery arrives, pop the pack in the fridge — as quickly as possible. The nematodes must be stored in the fridge until you're ready to use them, and they come with an expiry date of at least two weeks marked on the inside of the pack. As a genuinely live product, they should be used within two weeks of delivery. Miss that window and the nematodes simply die, and you'll get little to no result.

Step-by-Step: How to Apply Nematodes Properly

The application itself is refreshingly simple, but there are a few details that separate a treatment that works brilliantly from one that fizzles out. Follow these steps and you'll give your nematodes the best possible chance of hunting down every last grub.

Step 1: Prepare the Lawn

Before anything else, scarify the lawn first so there's no thatch for the nematodes to get stuck in. That layer of dead grass and moss acts like a barrier, trapping the nematodes before they can reach the soil. Then aerate the soil — a garden fork or a hollow-tine aerator does the job — as this creates gaps for the nematodes to travel down through to where the grubs are feeding.

Step 2: Check Your Moisture

The soil needs to be damp and moist when you apply. Nematodes are extremely susceptible to dry conditions and will die if they're not in a suitably moist environment. If it's been dry, give the lawn a thorough watering the day before or a few hours ahead of application.

Step 3: Mix the Solution

The nematodes are supplied as a powder. Dissolve the entire contents of the pack in a bucket containing 5 litres of water to create a concentrated stock solution, and stir it vigorously to get an even suspension. Don't leave the powder sitting in the water for hours before use — mix and apply promptly.

Step 4: Apply Evenly

Apply the stock solution to roughly a tenth of the soil area to be treated, then top up your can or sprayer and repeat two or three times until the whole area is covered. Working in sections like this is the trick to getting genuinely even coverage across the lawn rather than a heavy dose in one corner and nothing at the far end.

Step 5: Water It In

Once applied, water the nematodes in well so they're washed down as close to the pest as possible. This is not an optional extra — it's the step that carries the nematodes from the grass surface down to where the grubs are actually feeding.

Step 6: Keep It Moist

Keep the lawn moist for at least two weeks after application. This is the single most important aftercare task. The nematodes need that damp environment to move through the soil, hunt, and reproduce. If you get a dry spell in the fortnight after treating, water the lawn regularly to keep the top few centimetres consistently damp.

Nematodes vs the Alternatives

It's worth being honest about the fact that nematodes aren't the only game in town, even if they're my clear first choice for the home garden. Let's look at how the biological approach stacks up against the main alternatives.

On the chemical side, there's Acelepryn, a professional-use insecticide available in the UK and EU markets — but the crucial word there is professional. It's not something the ordinary gardener can buy and apply; you'd need to bring in a qualified contractor. That makes it a consideration for large commercial turf, sports pitches and golf courses rather than the average lawn.

The other alternatives are the non-treatment routes: cultural controls like keeping your lawn healthy and well-drained, and physical measures like netting to keep birds off while you sort the problem out. These have their place, but they manage the symptoms rather than dealing with the grubs themselves.

How Effective Are Nematodes, Really?

I want to set realistic expectations here, because that's the honest thing to do. Nematodes work brilliantly when the conditions are met — the right species, warm-enough soil, freshly hatched target pests, adequate moisture, and proper watering-in. When all those boxes are ticked, infected leatherjackets stop feeding and die within two to four weeks, and chafer grub applications provide at least six weeks of control. But the effectiveness drops sharply the moment you skimp on any one of those conditions. Below is my honest read on how the factors weigh up.

The Honest Pros and Cons

No treatment is perfect, and I'd be doing you a disservice to pretend otherwise. Here's my balanced take after several seasons of using nematodes in my own garden.

Availability: A Note for Readers Outside the UK

One important caveat worth flagging clearly: these live nematode products are essentially a UK and European affair when it comes to easy home purchase. For readers in the USA, nematode products cannot be shipped to the USA, and from Canadian suppliers such as West Coast Seeds, nematodes cannot be shipped outside of Canada. If you're reading this from North America, you'll want to look for locally supplied beneficial nematodes and grub-control products, such as Grub-Away, rather than trying to import — live organisms simply don't survive long-distance shipping and customs delays.

Who Should Use This Approach?

Nematode treatment isn't the right answer for absolutely everyone in every situation, so here's my quick guide to who'll get the most out of it.

Frequently Asked Questions

My Overall Rating

Taking everything into account — the effectiveness, the safety, the ease of use, and the limitations around timing and shelf life — here's how I score the nematode approach to grub and leatherjacket control.