Leatherjackets: finding them, treating them and fixing the damage
Leatherjackets are grubs that live just under your lawn and eat the roots. These videos show how to find them, what to treat them with, and how to get the grass back once they've done the damage.
What I'd put down to repair the damage
Power Packs: the 2.5kg bags cover 70 to 100m². The 8kg bags cover 228 to 320m².
Not sure of your size? Measure your lawnA thin, mossy lawn with leatherjackets under it
A thin, patchy, mossy lawn in Glengormley at the end of March, with leatherjackets living just under the surface. We aerate it, scarify it and seed it.
- Looking for leatherjackets
- What the cores said about the roots
- A double pass with the scarifier
- When to put nematodes on
- Seeding at the end of March
- Getting the seed into the soil
What happens in this one
The grass is very weak in patches, which is the usual sign. Leatherjackets are grubs that live just below the surface. If you go looking and don't find any, it doesn't mean they're not there. This lawn's riddled with them.
The cores show roots going right to the bottom, so the lawn's fairly healthy underneath. It's just under pressure from the grubs. Then it gets a double pass with the scarifier, two directions, to pull out the dead grass, moss and some of the thatch. Seed sitting on top of thatch won't grow.
For the leatherjackets themselves, it's nematodes in the spring, watered in well, and again in the autumn. You might have to do it two or three years in a row.
Then the question that comes up every spring: can you seed in March, or are you wasting your money? There's one thing that trips people up every year.
Don't let leatherjackets kill your lawn
Is your lawn dying in front of your eyes? You might have an enemy underneath it. Jason and I were halfway through treating this lawn for leatherjackets, and trust me, it had been a disaster zone.
- What leatherjackets are
- How to find them
- The signs to look out for
- Removing the thatch
- Using nematodes
- The professional treatment
What happens in this one
Leatherjackets are grubs that live under your grass and turn into daddy long legs. In September and October the daddy long legs lay their eggs in your lawn, the eggs hatch over the winter, and the grubs feed just under the surface. A lawn can support a certain number of them. When there's a lot of them, it starts dying off in front of your eyes.
To check, dig a hole. They'll be right near the top of the soil. If you don't find any in the first couple of holes, that doesn't mean you don't have them. The other giveaway is the birds. One or two pecking at your lawn is nature, but lots of them, all the time, means they're having a feast.
Then the ways to deal with them. Removing the thatch is the first, because that's where they live. Nematodes are next, and there's a lot to get right with them, from the soil temperature to the watering after. Jason and I go through it all.
We also try sweating them out of the lawn with the sprinkler and a sheet of black plastic. Watch it to see what comes up.
Treating leatherjackets with nematodes
If you're looking at your lawn and asking why it's dying in patches, it could be leatherjackets. I show you how to check for them, then take you through putting nematodes on, from opening the pack to watering them in.
- What a leatherjacket is
- Where to dig for them
- The black plastic test
- Measuring your lawn first
- Storing nematodes
- Marking the lawn out
What happens in this one
A leatherjacket is the larva of the crane fly, or daddy long legs. Its job is to eat, and it feeds on the roots of your grass. A lawn can live with a few, but when there's a high number of them, that's when the problems start. New builds seem very prone to them, and I'm not sure why.
To check, dig a couple of holes. There are none in this lawn, but they'd be in the thatch and just below the surface, round the roots they feed on. You can also soak the grass, cover it with heavy black plastic overnight, and the grubs come up to the surface. Some people stop there, but I think that's only a half measure.
Nematodes are a live product, grown in a lab, with a best before date, so if you're not using them straight away, keep them in the fridge. They're sold by the area they cover, so measure your lawn first. The brown stuff in the pack is only clay, a carrier, and the nematodes are too small to see, so scrape every last bit into the applicator. Mark your lawn out in zones with posts or plant pots, so they go on at the right rate.
There's some bad news if you've had leatherjackets this year, and it's why I keep the applicator for next year.
Fixing leatherjacket damage
One of my early videos, but the advice still stands. I go through what leatherjackets are, how to spot them and my top five tips for keeping them under control, and we repair the damage they did to this lawn.
- The leatherjacket life cycle
- When the damage shows
- The signs to look for
- How nematodes work
- My top five tips
- Repairing the lawn
What happens in this one
Leatherjackets are the larvae of the crane fly, or daddy long legs, the same way maggots turn into bluebottles and caterpillars turn into butterflies. Their job is to eat, and what they eat is the roots of your grass. A female crane fly lays up to 300 eggs in a lawn, and they hatch 10 to 15 days later.
From August to April you'll probably have no idea they're there. They're small, and the grass replaces the roots they eat. From late April to early June they grow fast, and the grass can't grow roots quickly enough. That's when it goes yellow, the plants come away in your hand with barely any roots, and the birds move in.
Nematodes are tiny worms that live in the soil. They climb inside the leatherjackets, release bacteria and kill them. It's gruesome, but it works in our favour, as long as the soil is warm and moist. When this video was made there was no chemical control for leatherjackets. There's a professional treatment now, and I cover it in the first leatherjacket video in this guide.
There are also a few things people swear by that you can try at your own risk, and one of them you've probably got in the fridge.
About this guide
Two of these are recent jobs, one in Greenisland and one in Glengormley, and both lawns were full of leatherjackets. The other two are early videos of mine. One goes through the life cycle and the repair, and the other shows you how to check for them and put nematodes on.
Treating the grubs is only half of it. Once they've eaten the roots, the lawn needs seed, so when you sow, the Seeding Success Duo puts Seed and Establish Pro with Seaweed Lawn Booster, feeding the soil, not just the lawn. About a month later, move on to this season's Power Pack.
Worth taking home
The bits from these videos that work on any lawn with grubs in it.
Common questions
How do I know if I have leatherjackets?
Dig a small hole. They live right near the top of the soil, so you'll see them just under the surface. If you don't find any in the first couple of holes, that doesn't mean you don't have them.
The damage shows most from late April to early June. The grass goes yellow, the plants come away in your hand with barely any roots, and you get lots of birds pecking at the lawn. That's in video 2 and video 4.
What's the best way to get rid of leatherjackets?
The most effective treatment in the UK is a professional one, so it has to go on through a lawn care company that's trained and insured to use it. It can only be used once a year, and the best time is October, after the daddy long legs have laid their eggs. It covers chafer grubs too.
Yourself, you can scarify to take out the thatch they live in, and put nematodes on in spring or autumn when the soil's between 12 and 20°C. Water them in well for the next couple of weeks, because that's where most people go wrong.
Will my lawn recover from leatherjackets?
Yes, once you've dealt with the grubs and got seed into it. The lawn in video 1 had roots right to the bottom of the cores, so it was healthy underneath, just under pressure.
Aerate, scarify, seed, and drag the seed in so it's touching the soil. Video 4 shows a lawn being repaired after the damage.
Are leatherjackets the same as chafer grubs?
No. Leatherjackets are the grubs of the crane fly, or daddy long legs. Chafer grubs are the grubs of chafer beetles. They do the same kind of damage, and the professional treatment covers both.
