6 July 2026

Is this Leatherjackets destroying my lawn

Q. “Hi, I’m looking for advice regarding my lawn (see pictures). As you can see there are lots of areas of straw like patches and also bald patches which I am unable to cover. These pics are just after watering due to the hot spell, and it has slightly worsened with this, although I’ve had trouble for many months with these patches. I’m not sure if it is disease or leather jacket infestation so don’t know how to treat. The lawn was newly laid around 12 months ago, the dead areas of grass are still securely attached and does not lift. Thankyou” Nichola by email

A. Good Afternoon Nichola, Many thanks for your enquiry. Unfortunately it is impossible to diagnose the problem from the damage as there are a couple of pests it could be, but it is most likely leatherjackets especially as you had turf laid 12 months aga. Turf growers are no longer allowed to use pesticides to treat the turf, so often new turf can contain undetected leatherjackets. Your photos does appear to show typical leatherjacket damage, but it could also be a chafer grub infestation (the damage is pretty identical from both pests). You can see that they have been drawn to the moisture and warmth of the fence and have been attacking the roots close to it.

We need to confirm which you have by lifting a piece of turf – it looks like you could easily peel back your turf by the fence. Alternatively, check where any birds are pecking and see what is there – leatherjackets look like this :-

Chafer Grubs are white, creamy grubs with a yellow head and look like this :-

I suspect it is leatherjackets and you will find those and if that’s the case, you would need to treat the lawn with Nemasys Leatherjacket Killer and this is what I would do……… The best time to treat leatherjackets is in the autumn, but the nematodes will help when applied at double strength at any time of year. By treating now with Nemasys Leatherjacket Killer  you will kill lots and this will allow you to recover the lawn and then you can “clobber” it in the autumn i.e. treat once the daddy long legs have emerged and then again just before temperatures drop. I am confident the nematodes will work, but you will need to apply at least twice this year and if they are in your area it will then become a yearly application to keep them away. If you decide to give it a go I would treat as follows :-

1. Apply another lot of Leatherjacket Nematodes NOW at double strength.
2. Feed the lawn with Lawn Food / use a root treatment like Root Success to help the lawn recover.
3. Watch out for daddy long legs emerging in the summer i.e. normally mid-August and then aim to apply Nemasys Leatherjacket nematodes at single strength 2 WEEKS after the mass emergence of the daddy long legs.
4. You can repeat the autumn nematode treatment 6 weeks later to kill any later emerging daddy long legs / crane flies to make sure you get them all.
5. Give your lawn a final feed with a low nitrogen Autumn Lawn Feed between Sept – Feb to encourage root growth.
6. Add a autumn treatment of Leatherjacket Nematodes (applied in late Sept) to your normal lawn care routine to keep them away.

I hope this helps Jon @ Green Gardener

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