CraneFly on Leaf - the parent of the LeatherJacket Larvae pest

Thanks to the extended period of wet weather we are noticing that a common garden pest – the leatherjacket – is on the rise. A normal component to most UK gardens, this year’s damp conditions have favoured the survival of the eggs and larvae, and therefore are making them a dominant pest for 2024.

Have you ever noticed patches of yellowing or dead grass in your garden? Or a seedling plant that has collapsed having been eaten at soil level? It is quite possible that you may have a leatherjacket infestation.

Leatherjackets are the larvae of the crane fly (daddy-long legs), with some 350 species in Britain. Crane flies, typically seen between late July and early September, lay their eggs in late summer, with hatching occurring 2-3 weeks later. Many of the crane fly larvae are an important part of your garden biodiversity helping to process decomposing organic matter.

Those that cause damage, and thus what we are addressing here, are the larvae that feed on living plant material. These larvae are up to 30mm long, with greyish brown tubular bodies and no legs or obvious head. It’s these Leatherjackets, mostly feeding on grass roots, which cause the damage in our gardens.

Signs of a Leatherjacket infestation

Here are some of the common signs for a leatherjack infestation.

Yellow Patchy Grass

Perhaps your lawn is developing patches where it is turning yellowish or brown, possibly dying too? Lift the affected grass area and look for signs of leatherjackets in the surface layers of the soil.

Increased Wildlife Visitors

Leatherjackets are a normal part of the garden biodiversity. Birds and Hedgehogs love to feed on them, so if you notice an increase in your garden visitors, like flocks of birds landing for a feed this could be an indicator. It is important to note that there are other grubs the birds search for too.

Spongy or Damaged Turf

As a result of the larvae eating the grass roots it is possible for your lawn to feel spongey or uneven. If you notice this, take a look at the top layers of the soil, looking for signs of leatherjacket activity.

Physical Evidence – The Larvae

If the infestation is bad you may notice the leatherjackets on the surface of your lawn after a wet spell. You can simulate this by soaking the ground and covering with a light impervious material for a day. If you have an infestation you should see a large number of the grubs when lifting the material the next day.

What you can do to manage the leatherjackets in your garden

Make the Soil less Hospitable

Leatherjackets love wet compact conditions so the easiest first step is to aerate your lawn regularly. Not only will this support better drainage, but it will expose the leatherjackets to natural predators like birds and beetles.

Encourage Natural Predators

Leatherjackets are part of the natural garden ecosystem. It is only when they are out of balance that they cause damage. Encouraging beneficial wildlife like birds, hedgehogs and ground beetles to your garden can help you to maintain the numbers naturally. You can do this by providing food, water and shelter that supports these natural predators.

Use Biological Control

If you have a significant problem you may need a more targeted approach. There is a natural solution. Nematodes can be used as a biological control for Leatherjackets. These microscopic roundworms are natural parasites of Leatherjacket larvae and can significantly reduce their numbers without harming other beneficial organisms.

Many of the methods to manage leatherjacket infestations can be incorporated into your garden care regime. By understanding the leatherjackets more you can begin to make the environment less hospitable and encourage the natural balance in your garden.

Our Garden Care & Development team can help identify and manage these and other pests and diseases. If you haven’t got the time, skills or energy to look after your garden, get in touch.