All lawns are susceptible to pests and diseases. Arguably, the most common pests are leatherjackets or chafer grubs. If left alone, they can cause enormous damage to your sward.
Don’t worry though, there are things you can do to identify, prevent or even treat infected areas. But timing is everything when it comes to treatments, so keep reading to find out what you should be doing.
In this article I’m going to help you find out whether or not you have an infestation. And if you do, how to identify which type of bug it is – leatherjacet or chafer grub.
Then I’ll explain how they got there, how to treat them, when to treat them and more importantly how to prevent them.
So, let’s get going
Identifying the pests in your lawn
If you notice patches of dead or dying grass in your lawn, it may be a sign of a infestation. You can check for the presence of leatherjackets by digging up a section of affected turf and examining the soil and roots for the small, worm-like larvae.
The first thing to do is to look under the turf. If you find 5-6 grubs in one small section (approx 0.5m2) of the grass then it’s likely you have an infestation. Another way to recognise an infestation is that an unusual number of birds will be pecking at your lawn.
For example, in normal times you might have 1 or 2 birds on the grass but when you have grubs in it, your lawn could be completely covered in a specific spot as they hunt for their little treats.
It’s much better if you can catch them between July and September – more on this below. Anyway, once you’ve decided you definitely have an infestation, then next thing to do is work out what exactly is causing all this damage.
These are the larval stage of crane flies also known as daddy-longlegs. Crane flies lay their eggs as larvae in Autumn, then these larvae hatch and feed on the lawn throughout the Winter before growing bigger and eventually turn into adult daddy longlegs the following Summer – whom then repeat the cycle.
Here’s what leatherjackets look like
Key features of a leather jacket:
- They don’t have any legs
- They are usually brown/black in colour almost like a worm
- Their skin is very tough and feels leather-like if you pick them up (hence their name)
- They have a very distinctive head
Chafer grubs are the larvae of chafer beetles. They live in the soil until they become adult beetles. In fact the larvae is often bigger than the adult beetle itself. Like leatherjackets, they feed on the roots of the lawn, causing extensive damage.
Here’s what chafer grubs look like
Key features of a chafer grub:
- They have a body that’s shaped like a ‘C’
- They have a creamy-white body that looks a bit like small segments
- They have an orangey-brown head
- They have 6 legs positioned right up towards the head
- Their body can be anywhere between 1cm and 3cm long
How do they get in the lawn
Both leatherjackets and chafers start off as larvae under the soil bed. They can remain in the soil for several years. In late summer or early autumn, they pupate and eventually emerge as adults the following Spring.
If they’re not dealt with in good time after hatching from (Autumn), they’ll feed on the grass throughout the whole of the Winter. It won’t be until late Winter or early spring until you’ll actually see the damage and by then it would be too late to do much about it.
This is a good time to get going with your overseed and a proper fertiliser programme.
What are the symptoms of leatherjackets and chafer grubs
The symptoms of both these creatures are pretty much the same. Roots being eaten, grass turning yellow and dead patches in the lawn. Seedlings also collapse due to being eaten at the roots.
If you notice patches of dead or dying grass in your lawn, it may be a sign of infestation. You can check for the presence of leatherjackets or chafer grubs by digging up a section of affected turf and examining the soil and roots for the small, worm-like larvae.
More damage can be caused when its chafer grubs
When it’s chafer grubs, animals will want to eat these grubs because they are perfect for snacking on. Just like we snack on chocolate. Thereby causing the grass to be torn up even more. Below is an image of an infestation which has gotten out of hand.
Assuming you’ve come to this page because you already have a problem, and now we’ve identified the problem let’s look at how and when to treat them.
How to treat leatherjackets and chafer grubs
You won’t find any chemical treatments that can be used against an infestation of either of these creatures. So, really your only option is prevention (as explained below) or ecological means such as:
- Using Nematodes
- Letting the birds eat them
- Letting other predators eat them (Badgers, Hedgehogs or Foxes)
- Wating until they go further into the soil bed (late Spring/Summer)
Let’s examine each one in more detail
This is the only real treatment available in which we can control when they are used.
Nematodes are a natural treatment and can be purchased online then applied to the lawn when temps are above 12 degrees and less than 20 degrees (always follow the manufacturers instructions). You can generally apply these alongside any lawn feed too
They will latch onto the larvae and kill them. The best thing is that nematodes won’t cause any harm to anything else so they are environmentally friendly too.
However, if nematodes are to be successful against leatherjackets or chafer grubs, then they need to be applied while the larvae are super small (not when they are just about to turn into adults).
Meaning late Winter/early Summer is too late for applying nematodes, while Autumn is the perfect time to use nematodes.
On the other hand, you might be better just watching on and letting nature do it’s thing. Here’s what I mean.
Letting the birds eat them
The best way is for the birds to eat them. Yes these birds will likely tear up your lawn too but at least if they eat them, the bugs will be gone and that means no more damage to the roots of your sward.
Letting other predators find them too
If the birds don’t get to them first, then you’re likely to have badgers and hedgehogs or even foxes hunting them down too. The only problem with this is that these types of predators will make your garden look a lot worse than if the birds were simply pecking at the lawn.
When to treat leatherjackets or chafer grubs
To be honest once your soil has been attacked, you’re probably too late and there’s not much you can do immediately, other than watch the birds dive head first into their tasty treats while your beautiful sward gets (hopefully minimally) damaged.
You can only use Nematodes in Autumn – alongside your Autumn Feed application – because that’s when the grubs are at their smallest and more susceptible to being killed.
So, if you find the damage in Spring, I’d highly recommend applying Nematodes the following Autumn so that you can break the cycle of eggs being laid. You’ll be able to see new crane fly larvae from July to September.
In the meantime though, I also suggest getting on with fixing the mess that’s been caused over the previous Winter.
How to fix the damage prevent them in the future
Making the soil more acidic
Crane flies don’t like acidic soil. If you’re able to prevent crane flies, then you’re also able to prevent them from laying their eggs in your beloved lawn. iron sulphate is one product which will help to prevent crane flies from nestling in your grass. A couple of applications per year of iron sulphate will certainly help to prevent an infestation.
Having a regular fertiliser programme
By far the best way to prevent them is having a regular fertiliser programme. I always recommend doing a minimum of 4 feeds per year. With any other lawn care treatments, of which there are lots, being optional.
A regular fertiliser programme is always useful for keeping your grass in tip-top condition. But it’s also important to mention that an Autumn and Winter feed will significantly minimise the damage if you have not identified a problem or applied Nematodes before the cooler months set in.
- These grubs will feed on your lawn during the Winter by eating roots
- Other animals are likely to hunt down chafer damage, potentially causing more damage
- You’ll most likely find the damage in late Winter
- If so, focus on fixing the damage from mid Spring before applying Nematodes the following Autumn
- Regular fertiliser applications and Iron Sulphate can help deter crane fly and chafer beetles from laying their eggs