As passionate gardeners, we know that there are lots of struggles and challenges when it comes to maintaining a beautiful lawn. In most cases, the problem stems from crummy soil and lack of sunlight, however sometimes it can be due to a pest infestation. For example, have you noticed the appearance of any brown patches on your lawn? If so, that could be due to a very common lawn problem present in the UK at the moment, the leatherjacket grubs (crane fly larvae).

Table of Contents:

What are leatherjackets?

Crane flies, also known as daddy-longlegs, emerge from the soil in huge crowds during late summer. The lifespan of such flies is around fifteen days as their main purpose is to mate.

Once the adult crane fly lays its eggs on the ground, the larval forms, known as leatherjackets, burrow deep into the soil and wait till the coming summer to resurface. Once fully grown, daddy-longlegs emerge from the ground and can be seen around England between April and October. They often lay their eggs within the first 24 hours and give life to a new generation of larvae.


Leatherjackets are one of the most common causes of lawn diseases across the UK and a big problem for lawn enthusiasts and gardeners. They feed on grassroots and crops, and well, the consequences are dead grass and brown patches on the lawn.

Related: Box Tree Caterpillars Invasion: How Does It Look and How to Stop It

How to tell if leatherjackets are a problem in your lawn?

The first sign that you have a leatherjacket problem is birds pecking the surface. Even if they are a garden pest, daddy-longlegs are a valuable food source to many birds like rooks and crows, and other animals. Birds leave lots of small holes in the lawn in an attempt to drag out some larvae, which also leads to additional damage.

The second sign as we said above is yellowish grass and brown patches on the lawn. In places with distant plants, like vegetable gardens and pots, the first sign of an attack is the unexpected death and fading of the plants. 

The most active season with the most damage is spring when the leatherjackets are fully grown and start feeding again. Also, the damage is more severe if the autumn has been wet and mild.

If you notice these unusual circumstances, make a few small holes under the infected area. Leatherjackets are often located in stressed areas, such as shady and wet patches, or the lawn edges. 

Liftback the turf and if you see 3-4cm long grubs of a black or greyish brown colour, yes, you have leatherjackets in your lawn.

How to get rid of leatherjackets in my lawn?

The best time to control the leatherjackets in lawns is in the larvae stage, not flies. There are various ways to treat and control a leatherjacket infestation. The most important thing is to kill all the living larvae in the lawn. You can do that by picking them by hand or with the help of biological agents.

  • Chemical control – As we have become a free of pesticide nation, currently there is no approved chemical insecticide for leatherjackets control. Recent reforms in EU law restricted the use of pesticide. Still, you can apply a biological solution, which is just as effective as the chemical ones – the nematodes.
  • Biological control – Nematodes are microscopic and safe for the environment worms. They are native to Britain, and some might be on your lawn already. To be effective, the leatherjacket nematodes need to be applied to moist soil between August and October when the ground temperature is still warm, and the leatherjacket grubs are active. The function of nematodes lies in their ability to penetrate the leatherjacket grubs and release deadly bacteria that stops them from feeding.
  • Organic control – another treatment for leatherjackets in lawns is to cover the area with a light-resistant plastic sheet, like black polythene. This will encourage the leatherjackets to come to the surface of the lawn. Make sure to saturate the soil with water, or, for an even greater effect, you can wait for heavy rain. In the morning the leatherjacket grubs will be lying on the surface and can be left for the birds to take care of, or destroyed.

How to deal with leatherjacket lawn damage?

Depending on how bad the leatherjackets invasion is and the condition of your lawn, you have two options – to repair or replace the lawn.

Repair the lawn

If the damage is not that severe, repairing it is the best decision, and you have the chance of eliminating the problem. If this is your case, follow the steps listed below:

  • Scarify your lawn – remove the excess thatching, that will improve the overall health of the lawn and will prepare the soil for the following treatment.
  • Kill the leatherjacket grubs – apply nematodes as we explained above and remember, leatherjacket treatment with nematodes only works when:

– The grubs are active and close to the surface.
– The soil is moist (keep the soil wet at least two weeks after that).
– When the temperatures reach 12°C.

  • Spread some good quality grass seeds – you can find different types of seeds depending on the type of your lawn. Never leave your lawn seedless, because moss and weed problems are guaranteed to occur.
  • Once you’re done with seeding, apply a fertiliser that will help the new grass to establish and grow quickly.

If there is no rain, make an effort to water your lawn regularly, and in a couple of weeks the grass will grow, and the lawn will get a lush appearance.

Replace the lawn

If your lawn is completely destroyed by leatherjackets and the birds feasting on them, you might consider replacing it entirely. So, here are the steps you should follow:

  • Apply a weedkiller – It will kill the grass along with roots, which in turn will cut off the leatherjackets food sources. Leave it for a few weeks so it can reach the roots, this reduces the risk of old weeds growing through your new turf.
  • Remove the turf – with the help of spade, get rid of the old turf once it is dead.
  • Rotate the soil – for a couple of weeks, leave the soil open and welcoming for birds, so that they come and eat the leatherjackets. Keep turning the soil daily to endanger as many grubs as possible. We know that rotavating is hard work, even for small lawn owners. The best solution is to leave this difficult job in the hands of professional gardeners, who have all the tools needed.
  • After a few weeks in soil turning, the leatherjackets must be drastically reduced. Now you can level the ground and lay new turf.

How to prevent further leatherjackets infestation?

Cut, scarify, aerate and fertilize your lawn frequently, so it is thick and hard to penetrate for Crane flies.

Regularly check the soil and plants for signs of leatherjackets and encourage the birds’ population with bird boxes and feeders.

Prevention is always better than treatment and dying grass, so apply the leatherjacket control product (nematodes) seasonally as a preventive measure. Remember that the eggs can’t be controlled, so don’t be tempted to apply the product too early, before the adults have set their eggs and they have been already hatched.

Takeaways

  • Leatherjackets are one of the most common causes of lawn diseases across the UK.
  • The first sign that you have a leatherjacket problem is birds pecking the surface.
  • The best time to control the leatherjackets in lawns is in the larvae stage, not as flies.

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image source /  aeiddam0853578919

  • Last update: February 24, 2020

Posted in All About the Lawn, Garden Advice

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