Leatherjacket Lawn Pests – The Complete Guide

By | 15/03/2019
Lots of leatherjacket grubs
Updated: March 2019

Download my leatherjacket fact sheet

This is a summary PDF of this blog post in an easy to see, printable format.


What are leatherjackets?

Two leatherjacket grubs
Two leatherjacket grubs

A leatherjacket is the common name for the larval stage of an insect called a crane fly. They are in the Tipulidae family of insects. In the UK, two species of this family are pests to lawns. These are tipula oleracea and tipula paludosa. Oleracea is the much more common species.

The adult form of these insects are commonly known as daddy-long-legs. These are the large, clumsy insects which fly around our gardens in late summer and early autumn. They are often seen bumbling along the ground, getting trapped in windows and flying into our faces when we least expect it!

An adult crane fly (Tipulidae)
An adult crane fly (tipula oleracea) sitting on a ledge.

The leatherjacket life cycle

The adults are active in late summer into autumn. After they mate, the females lay their eggs on scrub grassland and on lawns. These eggs hatch into grubs two or three weeks later, depending on conditions. These grubs (the leatherjackets) move through the soil and feast on roots of plants found around them. They reduce their activity and dig deeper into the lawn in the winter due to the cold, but start up again in the spring. They need to eat more as the grow larger. Affected plants die suddenly. Lawns can be devastated.

The four life stages of the lawn leatherjacket and crane fly
Crane Fly (leatherjacket) life cycle stages

In late spring the grubs pupate, forming a protective layer around themselves. Inside this pupae the insects transform over several weeks into the adult crane fly.

Leatherjacket pupae
This is the hard-cased form which the leatherjacket grub takes on once it is ready to change into a crane fly.

They then emerge when they are ready. Unfortunately for them, their adult lives are very short. Their only aim is to find a mate and lay eggs for the next generation. They don’t even have any mouths to eat food! As soon as their energy has been expended, they die, leaving the next generation as eggs in your lawn.

Leatherjacket and crane fly life cycle diagram
The life cycle of a crane fly, from leatherjacket grub to adult.

How can you spot leatherjacket grubs in your lawn?

Finding out if you have a leatherjacket infection in your lawn is quite simple. You only need a small pocket knife and good knees. Firstly, have a general look at the lawn and see if you see any patches of obviously dead or dying grass which seem rather out of place or randomly distributed. Down on the ground, have a closer look at these areas. First thing to do is to grab a handful of grass and try to pull it up. Healthy grass will not budge, being held in place by the roots. Grass subjected to a heavy grub attack will come away easily, almost like a carpet. This is because the roots holding it to the ground have gone.

Leatherjacket damage on grass
Leatherjacket damage on a lawn.
Leatherjackets surface feeding evidence
Evidence of leatherjackets in a lawn. The RED arrow is a hole which the grub made to come to the surface. The BLUE arrows near the hole show grass plants eaten by the grub.

Next, dig into the lawn and have a look to try to identify a grub. This is important as you need to confirm the pest you are trying to deal with. In a UK lawn you are only likely to encounter leatherjackets, chafer grubs, cutworms or wireworms. Wireworms are thin and orange. Cutworms are quite large, ‘C’-shaped blue-grey caterpillar type grubs. Chafer grubs are white, usually curled up in a ‘C’ shape with a black head. Leatherjackets are darker coloured, straight and can be between 0.5cm to over 2cm long.

Leatherjacket grub close up
A close up photo of a Leatherjacket grub.
A selection of wriggling leatherjacket grubs dug from a lawn in Exeter

What damage can leatherjackets do to your lawn?

In large numbers, leatherjackets can be a very destructive lawn pest. They can destroy a lawn completely. Such a severe attack is unusual, but even lighter damage can dramatically affect the look of your lawn which may require expensive repairs. The best way to deal with any possible infection is to make sure that it doesn’t get out of hand. Just one or two leatherjackets in a lawn will barely be noticed. When the they appear in large numbers you should be concerned. Measures to keep population numbers down should be taken as soon as they are detected in a lawn.

Leatherjacket lawn damage
A lawn in Exeter destroyed by leatherjackets over winter.

A mild, damp winter will bring leatherjackets closer to the surface and they will be able to keep feeding. As a result, damage to lawns in spring is always a lot worse after a mild winter. If your soil does not freeze in winter, be on the lookout for grub damage in the spring.

Further problems can arise from large animals taking an interest in the grubs. They offer a tasty meal, especially during the lean winter months. If a large population of grubs are found by a badger, fox or even birds, the subsequent damage to a lawn can be devastating! A lawn can be ploughed up overnight and will need to be repaired.

Lawn damage cause by an animal finding leatherjackets
Lawn damage cause by an animal finding leatherjackets.

How can you control leatherjackets?

There are no chemical treatments or pesticides available to control leatherjackets!

Environmental legislation withdrew all professional and home use insecticides in 2015.

The only way to control a leatherjacket infection in 2019 is to try to control populations using non-chemical methods. Here are a couple of different approaches you can try. Like most garden pests, the best results come from using several methods rather than just relying on one.

Method 1 – Black plastic sheeting.

You may be able to encourage the grubs to the surface of the lawn using black plastic sheets, tarpaulin or thick bin-bags.

First, you thoroughly wet an infected area of the lawn with a hose or watering can. This helps the grubs move through the soil. Then lay a thick plastic sheeting (not ground cover or anything which lets light through) over the lawn overnight or for a couple of days. Secure it with some stones or pegs. Then, remove it in the early morning and the grubs should be on the surface of the lawn. You can then either mow them up or leave them as a nutritious breakfast for the local bird population. Move the sheets to another affected area of lawn. This is an easy method for homeowners to keep the leatherjacket population down without professional help.

Method 2 – Nematode biological control.

A nematode worm
A nematode worm

This modern, natural treatment utilises a parasitic nematode worm called steinernema feltiae for the control of leatherjackets. After correct application to the soil, these microscopic worms find a leatherjacket grub as a host and infect them with a specific species of bacteria. This multiplies and kills the grub. Nematodes have to be applied under very specific conditions. They must be refrigerated upon delivery and then applied when the soil is warm and moist. Watering in the treatment is also very important as the nematodes must come into direct contact with the insect grub. These restrictions on the treatment mean that I am unable to offer it as a professional treatment, but it is available to homeowners online. Just google Leatherjacket nematodes for more information.

Method 3 – Encourage insect-eating birds.

Birds are natural predators of crane flys and relish the high populations of these insects in late summer. Encouraging birds into your garden with a variety of plants, water and bird feeders will build an army of predators which will keep a lookout for crane flys. They will despatch them before they even get a chance to lay their eggs in your lawn.

A Great Tit
A Great Tit © Francis C. Franklin / CC BY-SA 3.0

Method 4 – Dig them out!

For small areas it is quite possible to manually dig out the grubs. Using a knife or thin trowel cut into the soil in the affected area and look through the soil for the grubs. Pick them out and put them on the bird table. A few sessions of grub hunting should help minimise further damage and the lawn can be repaired with some seed.

Method 5 – Encourage strong grass roots.

If your lawn has not yet been attacked then you can minimise damage to grass by keeping it as healthy as possible. Grass with a shallow, weak root system will struggle with an insect attack. Deep roots from a strong, seeded lawn will be better equipped to cope and re-grow lost root mass. Aerate your lawn regularly and keep to a quality feeding programme to keep the lawn as healthy as possible throughout the year.

Method 6 – Garlic Spray (experimental control).

Farmers in Scotland are trailing garlic sprays as a treatment to keep leatherjacket numbers down. This has so far looked encouraging, especially for an autumn treatment. I will be starting a trial of this myself for lawns in 2019.

Method 7 – Beer spray (experimental control).

There is also a theory spreading around the lawn care community that an alcohol spray can control leatherjacket numbers. The theory behind this is that the grubs do not have a liver and as such posses no ability to digest alcohol. It is an interesting theory and I am running a test (spring 2019) to see if there is any truth in it. Spraying beer over your lawn may sound crazy, but there may be some sense to it. Getting them to drink it in sufficient quantities will be the hard part!

Beer spray for leatherjackets
Beer in my sprayer!

Leatherjacket controls to avoid

Some sources recommend rolling your lawn to compact the soil. The theory behind this is that it prevents the leatherjackets from moving through the soil and feeding. However I DO NOT recommend this for a domestic lawn. The resulting damage to the structure of the soil caused by compacting will be just as bad as a leatherjacket attack! Rolling your lawn is never recommended.

Also some professional lawn care companies have been offering to discretely spray lawns with their old stocks of banned insecticides. I cannot stress enough how bad this practice is. It is illegal to even hold stocks of these banned chemicals, let alone knowingly spray them as part of a business exchange. Both parties involved could get into some serious legal trouble if it was found out. If your lawn care company offers this, simply decline.

Will leatherjackets keep attacking my lawn?

Leatherjackets grubs are an annual lawn pest. Once they have turned into adults and flown away the lawn can be repaired. Your lawn may become re-infected with crane fly larvae from the next generation. I have seen lawns get infected in one year and never since. I have also seen lawns become infected several years in a row. It is just the random nature of these insects of where they happen to fly, mate and lay eggs. One you have confirmed that your lawn has leatherjackets, it is best to be vigilant every year so that you can minimise any damage and take action quickly.

If you have any success with any of these controls, or have any other ideas or suggestions in keeping their numbers down, I would love to hear about it. Get in touch or ask a question.

Kris Lord
The Lawn Man

Additional reading references

Additional photos of leatherjackets

Leatherjackets lawn damage
Leatherjackets lawn damage
Four leatherjacket grubs
A selection of leatherjacket grubs compared to a 50p piece.

Alternative search terms for leatherjackets:

Leatherjackets have also been called: leather jackets, leather backs, leather back grubs, grubs, european crane fly, true craneflies, true fly

9 thoughts on “Leatherjacket Lawn Pests – The Complete Guide

  1. Laura

    Hi
    I have some garlic liquid Regel G.
    Also have netted the entire lawn. Was thinking g of applying the garlic about now? Is this too early do you think?

    Reply
    1. Kris Lord Post author

      Hi Laura,
      A garlic spray is generally intended as a deterrent to prevent grub eating vegetative matter by giving them an unpleasant taste.
      September is too early as the grubs have probably not even hatched yet, let alone started feeding. I would leave it until much later on in the year.
      Regards
      Kris

      Reply
      1. Laura

        Hi Kris
        Ok that’s great. I have over netted my lawn and had eliminated over 1000 so far. ( plus prevented new ones entering my lawn) There are more males than females, so maybe my two years of nematodes worked with the females? Who knows?
        Today it is wet and around 100 have popped up out of the lawn 🙁
        I will spray 25ml to 5 litres of water and see what happens.
        Thanks for this advice.

        Reply
  2. Jill Hutchinson

    Hi,
    I have just found a leather jacket (very ugly i must say) on my decking, we do not have any grass in our garden so I was wondering if this beast is about to eat away and destroy my shrubs and flowers. I have never seen or heard of this bug before.

    Reply
    1. Kris Lord Post author

      It is unlikely to infest your pots, but they do eat roots of all sorts of plants. There are some other grubs though which can look similar which do like feasting on plants in pots, such as vine weevils. So vigilance on plant health is always key and investigate whenever there seems to be an unknown problem.
      Thanks for reading.
      Kris

      Reply
  3. Graham Troth

    Thank you Kris for replying. I found loads more at the surface this morning under the Black sheet. It’s so disappointing to see all this, but at least via your info on the website I can do things about it. Cheap beer was bought, actually it wasn’t too bad at 25p a can, ha!! I will do what you have suggested and keep you informed. Many thanks Kris, cheers Graham

    Reply
  4. Graham Troth

    Good afternoon Kris,
    I hope you don’t mind me getting in touch? Thankfully I doing your website yesterday. I have two lawns, not big but I am proud of them…until now. The past fortnight I could see there was something wrong. And looking at your info it’s leather jackets! Before my very eyes the grass was turning coarse and dead looking. I did what you said and put a dark piece of plastic over night…and behold they they were. I have aerated all the lawn, used my electric scarifier and cut low, it looks so sad now. My wife has gone out for some cheap beer too, ha! Tonight a have another piece of plastic to cover it all for two days. With that done Kris what are my next steps? I have some seed, also some lawn sad plus so wetting agent.
    I would love some advice now?
    Many thanks, you have saved me so far some heartache.
    Cheers Graham

    Reply
    1. Kris Lord Post author

      Hi Graham,
      Thanks for your comments.
      For now, I would continue to work on reducing the numbers of leatherjackets. Continue to try the black sheet method over different areas of the lawn and certainly look at applying a nematode treatment in the autumn as an organic control. A garlic spray can also be effective.
      As for repairs, overseed the lawn in the autumn and cover the seed with a dressing.
      I would then be vigilant over the winter and hopefully the lawn should make it through without any further damage.
      Thanks for reading.
      Kris

      Reply

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.