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How to get rid of Leather Jackets

Close up of leather jacket larvae on lawn

As we go from winter into Spring, we should be regularly checking our lawns for signs of leather jacket larvae damage. An infestation can utterly destroy a lawn so reducing the potential for damage by checking for grubs during the winter months through to the spring is recommended.

After a long absence of products to control Leather Jackets, in July 2023 a new pesticide product, Acelepyrn, was licenced for professional use in the UK for the control of Leather Jackets.   Acelepryn can be applied by a qualified lawn care technician following an Integrated Pest Management assessment, which is likely to involve a specific time frame, usually in September and October, for successful control.  This may also include the recommendation of scarifying prior to use to remove any thatch barrier which will prevent the product reaching the target.

What are leather jackets?

Leather Jackets are a common lawn pest with over 300 species in the UK and are regarded as a menace to our lawns. They are the larvae of the crane fly (daddy long-legs) and live just below the surface of the lawn until they emerge as adult flies during August-October. The adult flies then lay eggs and the new grubs start feasting, starting the cycle again.

They are black/brown in colour so can sometimes be difficult to see in the lawn, and it’s often not until they have damaged the lawn that an infestation is identified. Birds pecking at the soil in winter, and at lawns in spring and early summer, are another sign of leatherjackets’ presence. Larger predators may also dig them up from the lawn, causing larger damaged patches requiring repair.

What are the symptoms of a lawn with leather jackets?

The grubs feed primarily on the roots of the grass, so often there is no visible early sign of damage until the lawn starts to wither, thin out and die back.  The biggest indicator of an infestation is rapid thinning of the sward, starting from the shady areas or the edge of the lawn resulting in a very thin exposed sward as well as holes and divots left from birds pecking at the lawn in their attempt to feed on the larvae.  In extreme cases the entire lawn will become very bare as the grubs gain in size and appetite.  It is not uncommon for Leather Jackets to suddenly appear on hard surfaces during wet weather, such as adjoining paving or paths.

When do they usually appear?

They are most numerous after a warm, wet and mild autumn, which favours survival of the tiny, newly hatched leatherjackets. Though they can start feeding on the lawn then, they often fall victim to drought and don’t grow large enough over Winter to cause significant damage. Once the grubs start feeding again in Spring is when the real issues can begin.

Why is newly laid turf susceptible to Leather Jackets?

It is not unusual for recently laid turf to suffer from Leather Jacket infestation, especially in the first year or two since it was laid.  This can be very frustrating when so much time and expense has been invested into a new lawn.  In our experience we find that the Crane Fly prefers to lay their eggs on fresh healthy grass which will give them the best chance of successful reproduction, this is particularly noticeable in the shady/damper areas of the lawn. 

How can I repair the damage?

If you still have a fair amount of grass coverage, it may be possible to revive the lawn by undertaking mechanical lawn renovation during late spring or summer to repair the damage caused by these hungry critters. Completing scarification, aeration, overseeing and top dressing is often sufficient to bring a lawn back to life.

If a lawn has become extremely bare, returfing or reseeding the lawn may be the only option. Before going ahead with this, you want to ensure they are all out of the lawn, so we would recommend rotovating to expose any left to birds and predators before works go ahead.

Close up of crane fly on glass

Here are our top tips for identifying and controlling these pesky critters:

  • The easiest way to check for the larvae is to dig a series of small test holes with a fork, to a depth of about three inches below the lawn surface.
  • Pay particular attention to any areas of turf which appear stressed or thinning, particularly around the edges in shady areas, next to a fence or wall etc. If your lawn has been affected, you will notice that the root structure will be very weak so the grass may lift away easily from the lawn
  • Where possible try to eliminate the grubs from the lawn before they cause any more damage. The most effective solution is to either cover the whole lawn (or just the affected area) overnight with black plastic sheeting – this encourages the grubs to come to the surface so they can be brushed off and destroyed.
  • Birds eat many leather jackets, and you can help them by forking over the soil in spring to expose the grubs
Damaged edges of lawn from leather jacket

Is there anything I can do to prevent them coming back?

The best form of protection is prevention.  EU legislation has restricted the use of pesticides but you can employ organic solutions which don’t require a pesticide certificate. These are called ‘nematodes’, which are microscopic worms. They enter the grubs and infect them with a bacterial disease which kills them. Nematodes are available from various horticultural suppliers, but be warned; timing, soil moisture and the age of the larvae are all critical if the treatment is to be successful.

The Nematodes (or Steinernema Feltiae) should be watered onto the lawn between August and October when the ground temperature is still warm and moist. This is also the time the adult crane flies lay new eggs which hatch and often start feeding on the lawn before going more dormant over Winter. The young grubs are more susceptible to the nematodes at this time, but some have reported success with a further application during Spring (April/ May), once the soil temperature is above 12 degrees.

Leather jacket grub in hand

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