Question: Lawn seeding after leatherjacket damage

By | 15/07/2020
A readers lawn ready for seeding after leatherjacket damage

I received this interesting question in July 2020 about lawn seeding after leatherjacket damage. It was posted as a comment on my Leatherjacket Lawn Pests – The Complete Guide blog post, but I thought it needed expanding on.

Jim writes:

Hi Kris,

We have now removed all the grass from a 25 square metre area along with well over 1000 leatherjackets.

However, when we dig down to a depth of 4-6 inches we are still finding lots more so our current plan is to rotavate the area this week to clear as many more as we can find with a view to then reseeding a new lawn.

It would be helpful to understand the best timings from here to sow new seed that will also give us the best chance of avoiding a repeat attack.

Should we re-seed immediately or should we now wait until after any crane flies have stopped laying eggs this time around? Do they actually lay their eggs on the soil or do they find grass to lay their eggs?

Any guidance would be gratefully received.

Cheers

Jim,
Blog comment

Hi Jim,

Thanks for your question.

Well done on completely renovating your lawn after a leatherjacket attack. You should achieve a great lawn with such thorough preparation of the soil.

Seeding your lawn after leatherjacket damage?

As a professional, I would prefer to take into account the weather, rather than potential leatherjacket infestation. Timing of lawn seeding can be a key to success. You asked this in July 2020, so midsummer in the UK. Summer can sometimes be too hot for young grass and it can dry out very quickly. If you are not able to water a new lawn in it’s first couple of months, and the weather is sunny, you may have disappointing results.

However, you do have the advantage of plenty of time left in the growing season. So, if your leatherjacket repair does not work out, you can try again safely in the autumn. Save some seed after your first sowing so that you can patch it up seamlessly with the same grass if you need to.

Crane flies like to lay their eggs in thatchy, long grass. This is why thick turf is often a common target for the pests. A new, thin lawn is not a desirable environment for them. They need a food source for their young which is organic matter. In this case grass leaves and roots. Crane fly adults often blow into corners of gardens and are forced to lay eggs in any patch of soil. So there is still some risk, depending on the layout your particular garden. Personally, I would not delay seeding after leatherjacket damage.

Crane fly pests

Crane flies are an annual pest. Numbers from year to year strongly correlate to the environmental conditions. The winters of 2018/19 and 2019/20 were mainly warm winters following wet late summers. This is the ideal conditions for them and their numbers rocketed. If we experience a dry summer and cold winter in 2020/21, they may not be such a problem. But who knows what will happen?

Some people do claim to have them for many years. If true, this is very rare indeed.



The best thing to do would be to seed your lawn as soon as the soil is ready, and then be vigilant over the winter. At the first sign of any leatherjacket activity or thinning of the lawn start utilising some deterrent methods to reduce their numbers. Hopefully damage is kept under control before it is a problem.

I hope this is a useful answer. Good luck with your new lawn!

Kris Lord
The Lawn Man

11 thoughts on “Question: Lawn seeding after leatherjacket damage

  1. Stu

    Last year I purchased a considerable amount of top soil from Bradfords building supplies 18 tonne to fill in dips in the garden and to cover over tree roots that were breaking through the lawn.
    First I used a tiller over the existing garden lawn approx 150m then added the new top soil raked to a fine tilth then reseeded using a good quality seed and watered and fed religiously, by the end of the summer it was looking good and I thought by the end of this summer 2022 I should be very happy with it, however from then until now my lawn has been under attack from Leatherjackets, it looks like they moved in with the top soil delivery last year .
    I have spent hundreds now on a treatment that took me a day to water in correctly and have to repeat again in August then repeat in 2023.
    Should the soil be graded and safe before delivering to customers. I’ve lived here 26yrs and never have I had anything like this before I only wanted to spruce it up a bit now we have grandchildren running around, sadly now it resembles a very muddy football pitch on a rainy day, any ideas that I could use to speed the lawn recovery process on a bit quicker and kill off the Leatherjackets which are now turning into cranefly would be very welcome please.

    Reply
    1. Kris Lord Post author

      Hi Stu,
      Firstly, the leatherjackets probably didn’t come in with the topsoil. Eggs were most likely laid by the adult crane flies in September / October after you had seeded the lawn. They do like disturbed soil and I have had some lawns which have done exactly the same thing.
      the leatherjackets are an annual pest, so the more you can remove them from the soil now, the more quickly you can repair the lawn.
      Thankfully, as you have recently done soil work, the lawn will be easy to fix by just reseeding in spring. Lightly scarify the soil to break up the top surface and apply the same seed as before and the lawn should recover by summer.
      Leatherjackets in your lawn? Follow these steps …
      Thanks for reading.
      Kris

      Reply
  2. Dave

    Hi Kris – I’ve had substantial leather jacket infestation in my lawn. And I’m talking thousands of them. All over my patio, in my gravel and have completely killed off my lawn pretty much eaten everything and left a small amount of thicker sword (which I’ve read they don’t eat). Is it wise to seed even though I’m still pulling them out (6 weeks on, 2 nematode treatments and a good couple of weeks of black tarp). Have two young kids and would like some sort of lawn for them to play on (rather than mud lol). I’m going to give it a deep scarify and try and get as many as I can but they just keep coming….I can send pictures if you like but I’ve gone from stripes, to a field thanks in advance

    Reply
  3. L Harding

    Hi!
    We have found leather jackets in areas of our lawn (the affected area seems to be along the fence line which doesn’t get any sun except in high summer, so is very damp)
    We have dug over the area and removed all the leather jackets we can find and have been using black bags in other areas to see if we can entice anymore out and have found a few in other areas but no where near the amount we have found in the damp area a there are still some remaining.
    It’s not warm enough to apply the Nematodes now but we really want a nice lawn for summer. Is it worth us removing some of the old soil and replacing with new then turfing the area now and then treating with nematodes once it warms up to ensure we have removed them all and any that could arrive in the new turf.
    It’s really hard to know if there are many more remaining or not and if they will just kill off the new turf.
    Am I being impatient? Should we just prepare the lawn and leave until it’s warmed up and treat with nematodes before we lay the new turf? If so how long after applying the nematodes could we lay the turf?
    Thank you

    Reply
    1. Kris Lord Post author

      It is likely that the new turf that you bring in may have leatherjackets in it! This is one of the many reasons why I prefer to seed a new lawn.
      Prepare the soil and let it settle for a while. Then seed your new lawn. Don’t bother with turf at all as you may just go round in circles. Look after it during the summer by feeding it properly and mowing high and it will be in a great spot to resist leatherjackets next year.
      o be honest, there is not a lot of value in putting preventative nematodes down after the damage has already been done.
      Good luck.

      Reply
  4. George

    Hey Kris
    I really like how you mention Seeding your lawn after leatherjacket damage as it requires lots of experience and techniques to apply anything in your garden if you don’t have the experience how to reclaim your beautiful garden from unwanted pests and insecticides. I hope to come back to your site for more informative blogs like that.

    Reply
  5. Susan

    Hello Kris,
    Love your articles on leatherjackets and the post on “Should I seed or turf my new lawn?”.
    I have a query: Our recently laid turf lawn (October 2020) was completely infested by leatherjackets. Last weekend we dug up what was left of the lawn and will do the nematodes treatment this week. I wanted to check how long should we wait after the nematodes treatment to sow grass seeds.
    Any advice appreciated.
    Many thanks
    Susan

    Reply
    1. Kris Lord Post author

      Hi Susan,
      You can seed your lawn straight away.
      However, applying nematodes when they have all gone is rather pointless. It is literally closing the stable door after the horse has bolted!
      I would save them in the fridge and apply them later on in the year when they may be more effective as a preventative tool.
      Read the instructions and that will help time the application best.
      Thanks for reading.
      Kris

      Reply
  6. Karen Bryant

    Hello, I should like to ask when it would be “safe” to lay a new lawn after completely removing our previous one due to Leatherjack infestation. The original lawn /turf was laid only last Autumn and we noticed that it was not looking good. On inspection and lifting the edges(as you say just like a carpet) it was completely covered in these leatherjacks! We’ve now got rid of all the turf -do we need to dig it over and try and remove any of the ones that are left? When would it be safe to re-turf? Do we need to put any Nematoids on before? Hope you can help. Thank you

    Reply
    1. Kris Lord Post author

      Hi Karen,
      The leatherjackets may have come in on the turf you laid. If you have removed that turf and let the soil stay fallow for a while, the leatherjackets will probably have been eaten by birds or wriggled away in search of other food.
      Re-laying more turf may just reintroduce more leatherjackets and the lawn will certainly be susceptible to reinfestation.
      The best way to ensure a clean, pest free lawn is to sow grass seed. Not only will this be a much better lawn in the future, it will cost a lot less!
      Have a look at Should I seed or turf my new lawn? for more information.
      Thanks for reading.
      Kris

      Reply

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