How to Identify and Tackle Leatherjackets in your Lawn

Is your usually beautiful lawn suddenly peppered with yellow, dying spots? Are there more birds suddenly pecking at your grass? Perhaps new grass shoots have simply disappeared?

These are the symptoms of a Leatherjacket infestation; little grubs that live in your lawn. Leatherjackets are the larvae of crane fly (better known as Daddy longlegs), and they can do some severe damage to your lawn and other vegetation in the garden.

So, if your lawn has suddenly taken a turn for the worst, it could be a larvae infestation. This article is all about identifying this grass-eating insect with tips on protecting your lawn from its greedy maw.

What are Leatherjackets?

Leatherjackets are the larvae (or emelts) of the crane fly. While crane flies are harmless to humans, their larva can do plenty of damage to a lawn.

There are around 300 species of crane fly in the UK. But the most common and easily recognisable species is the Tipula paludosa (to use its scientific name).

Identified by their long, spindly legs, slender torsos, and long, thin wings, the Tipula paludosa is a nocturnal creature that, once fully developed,
lives a short life; solely to breed and reproduce.

Crane flies might resemble monster-sized mosquitos, but they’re pretty harmless. They don’t bite – in fact, adult crane flies rarely eat. But their larvae are hungry little critters, and they’ll munch through any vegetation nearby – especially grass.

The second most common crane fly species in the UK is Tipula Oleracea.

Crane Fly Tipula Oleracea

There’s little to distinguish between Tipula oleracea and Tipula paludosa on an aesthetic level. It can be difficult to tell them apart.

The main visual difference (although you’d probably need a microscope to see it) is that the oleracea has more prominent, oval compound eyes than the paludosa.

The main distinguishing feature between the two species is the time of their arrival.

The oleracea (also known as the Cabbage Fly Mosquito) appears when cabbage seedlings sprout between April and July. They’re also seen again between August and October.

Crane Fly Tipula Paludosa

Tipula paludosa appear just once a year – found in flight between August and September.

It’s during their flying cycle that they breed and lay eggs. Each crane fly lays around 400 eggs, which could quickly turn into a plague of Leatherjackets if they were all to hatch.

Whether the larvae pupate or not, it’s this larval stage of their life cycle that causes the most damage to your lawn.

The Crane Fly life cycle

The crane fly metamorphosises several times throughout its life span. Life begins as an egg laid by the mother, which develops into a larva. From a larva, it becomes a pupa, which is where the grub turns into the
flying insect we all recognise.

The larval stage sometimes lasts for just a few weeks but more typically takes around a year. The larva is remarkably resilient to low temperatures – in fact, they can survive temperatures as low as -10ºC.

The longer the larval duration, the more damage done to your lawn. During the winter, they burrow into moist soil or decaying organic matter. In the spring, they emerge to the earth’s surface to feed, which is when they do the most damage.

After the pupal stage, the adult crane fly no longer eats fibrous food, but they may feed on nectar. Adult crane flies live a short life: they exist merely to mate and deposit eggs. They die soon after.

The average lifespan of an adult crane fly is between 10 and 15 days.

What does a Leatherjacket look like?

We could be flippant here and show you images of leather jackets – the Fonz was famously never seen without his trademark outer layer.

However:

A Leatherjacket is typically 4-5cm in length and looks similar to a worm, not dissimilar to a caterpillar.

Grey/brown in colour, they have no legs and – to the untrained eye – it’s difficult to differentiate between its head and its bottom end.

As they move, they appear to slither like a worm. Check out this video to see a Leatherjacket in motion:

How do Leatherjackets damage my lawn?

Leatherjackets live underneath the soil while they overwinter, then emerge in the spring and live in the upper layers of the earth. They feast at night, which is when the damage to your grass takes place.

On warm, humid nights, leatherjackets come up to the surface of the soil to feed. They cut through the grass plant stem and munch holes into the foliage. They bite into the grass plant and pull it down into the ground, where they can feed in safety.

This creates small circular bald spots in your grass. When one patch of grass is decimated, they move to a new lawn area where they continue to feast.

What eats Leatherjackets?

Leatherjackets are tasty, nutritious treats for the birds (mainly crows, robins, and starlings), and you’ll find that moles are also partial to a leatherback.

Of course, we all want to encourage natural diversity in our gardens, but the birds and moles that Leatherjackets attract can also do some pretty hefty damage to your lawn.

Do I have a plague of Leatherjackets?

It’s rare to see a healthy Leatherjacket above soil during the day; they’re pretty easy to miss. However, if you go out on a warm, damp evening, you’ll see them emerging from the surface of the spill.

That’s when you know that you have a problem.

Alternatively, you could lift a small section of your turf to see if any Leatherjackets are hiding beneath the soil.

If you spot Leatherjackets, action is required to save your lawn!

How do I prevent Leatherjackets on my lawn?

Leatherjackets prefer long grass. So, one excellent, ecologically sound approach to prevention is to keep your lawn short during August and September. This is when the crane fly lays their eggs – they’ll avoid shorter grass as it offers less protection against predators.

Keeping the lawn short and well fertilised will help to limit the damage caused by Leatherjackets.

When is the best time to control Leatherjackets?

Leatherjackets are most active once the soil has reached 8ºC. This should happen around February/March in the UK.

It’s best to control the Leatherjacket population before they’ve reached full size. Catch them at 2-3cm if you can. Once they’re 4cm in length, they’re going to do more damage.

There are two ways of controlling the Leatherjacket population in your lawn: natural, biological solutions or chemical pesticides.

Biological control of leatherjackets with nematodes

Biologically controlling pests is better for the environment and less damaging to the food chain. Remember, birds and other animals feed on Leatherjackets, so biological approaches are preferable.

You can achieve biological control of Leatherjackets with nematodes.

Nematodes are microscopic, microcellular, non-segmented roundworms and a natural enemy of many insects and larvae. Once they’ve found their prey, they invade, and use it as a food source. It doesn’t take long for nematodes to work through your Leatherjacket population – just a few days.

In short: sometimes it’s best to let nature fight nature.

However, while some nematodes are beneficial, others (such as root-knot/root-lesion/dagger nematodes) will raid and destroy your vegetable patch.

Order nematodes that eat and destroy Leatherjacks online or at garden centres.

Make sure you get the right type!

Fighting leatherjackets chemically

Chemical pesticides offer an effective way to kill garden pests.

However, chemical agents can be harmful to humans and animals, so make sure you use them wisely and sparingly to protect the kids and your pets.

Chemical pesticides are spread or sprayed over the surface of the grass, which penetrates the ground and poisons the Leatherjackets.

You’ll need to employ a professional to apply a chemical pesticide for Leatherjackets, as they’re not widely available to buy within the UK.

Restoring bald spots after a Leatherjacket attack

It’s possible to re-sow bald patches of your lawn with grass seed.

In most cases, it’s just a case of overseeding (laying seed over your existing lawn).

When overseeding, ensure that the soil temperature has reached at least 10ºC – otherwise, the seed won’t germinate.

Check out our article on everything you need to know about laying grass seed.

Don’t confuse Leatherjackets with Chafer grubs!

Leatherjackets look similar to Chafer grubs – another garden pest that can damage your lawn.

Check out our article about Chafer grubs, and find out everything you need to know to control them in your garden.

Get started or ask for more information?

Hopefully, you feel a little better informed about identifying and tackling Leatherjacket infections, but if you have any further questions, we’d be delighted to help.

If you have questions – whether it’s about this article or anything else to do with creating a picture-perfect lawn, get in touch.

Email us at hello@moowy.co.uk.

We’re looking forward to helping you!

Thanks for reading!

Louis Hooft

Founder & Lawn expert

Introducing Louis Hooft, the founder of MOOWY and your reliable expert. With a profound love for stunning lawns and extensive experience in garden maintenance, Louis is here to assist garden enthusiasts in achieving a greener and livelier outdoors than ever before. Count on Louis for invaluable tips, clever tricks, and top-notch products to make your garden flourish!