Leatherjackets are the larvae of the crane fly. They live in the soil and feed on the roots of grass and young plants. This can cause significant damage to the lawn, especially if the grass suddenly develops yellow patches, becomes loose, or grows back poorly. Fortunately, you can control leatherjackets naturally using nematodes.

What attracts leatherjackets?

Leatherjackets are primarily attracted to lawns and moist soils where crane flies can lay their eggs. This often happens in late summer or autumn. As soon as the larvae hatch, they start feeding on roots and young grass blades. This weakens the lawn, leading to bare or yellow patches. Sometimes you also notice the damage because birds tear up the grass in search of the larvae. It is therefore wise to monitor any damage to the lawn closely, so you can intervene in time before the nuisance worsens.

Leatherjackets are primarily active in autumn and early spring, depending on temperature and soil moisture. In autumn, crane flies lay their eggs, after which the larvae hatch quickly and begin to feed on grass roots. They remain in the soil throughout the winter and can continue to feed in milder temperatures, although their activity is somewhat lower then. In early spring, they become more active again and start searching for food. This is the period when most damage to the lawn becomes visible, as the grass roots are weakened and the grass struggles to recover.

How do I know if leatherjackets are the cause?

One of the first signs of a leatherjacket problem is a deteriorating lawn, even if it receives sufficient water and nutrients. Plants may wilt and turf may feel looser because the roots have been eaten. Another clear sign is the presence of birds such as crows, blackbirds, and starlings, which peck at the grass in large numbers to eat the larvae. This can make the lawn look even more damaged. If you suspect that leatherjackets are the cause, you can carefully lift a patch of grass and search the soil for the legless, grey-brown larvae. They are easier to find especially in the early morning or in damp conditions.

Leatherjackets primarily cause damage through their voracious feeding underground. These are the most common signs of leatherjacket damage:

Root damage: Leatherjackets feed on the roots of grass and other plants. This weakens the grass or kills it, resulting in bare patches in lawns or pastures. The root damage can lead to the grass being unable to grow properly or to absorb water and nutrients.

• Bare patches in the grass: Due to their voracious feeding, irregular bare patches often appear in the grass, especially in spring. The turf becomes weak and is easily pulled up by birds or people.
• Damage to young plants: In vegetable gardens and young crops, leatherjackets can cause damage by gnawing on the roots or stems of young plants. This leads to wilting and death of the plants.

Indirect damage and additional risks

In addition to direct damage to grass and plants, leatherjackets can cause secondary damage, as birds and other animals plough up the soil in search of the larvae. This can further damage your lawn and irreparably harm the turf.

An effective and environmentally friendly way to control leatherjackets is to use nematodes against leatherjackets. These nematodes seek out the leatherjackets, penetrate them, and kill them from the inside. The advantages of this biological control method are:

• Environmentally friendly: Nematodes target only leatherjackets and leave other beneficial organisms in your garden alone.
• Effective and sustainable: Under the right conditions, nematodes can kill up to 95% of the leatherjacket population, helping to effectively control the pest.
• Safe for humans and animals: Nematodes are completely safe for children, pets, and other animals in your garden, making them ideal for use in gardens and on sports fields.
• Easy to order: Order the nematodes online today and have them delivered tomorrow!

Controlling leatherjackets and controlling leatherjackets in lawns

Controlling leatherjackets is especially important because the larvae can cause significant root and leaf sheath damage in a short time. If you wait too long, the turf becomes thin, loosens more easily, and secondary damage occurs as birds and other animals search for the larvae.

When controlling leatherjackets, the goal is not to kill everything, but to restore balance. Biological control with insect-parasitic nematodes can be suitable for this, as you work with natural enemies that are active in the soil. Nematodes specifically target larvae and leave most beneficial soil organisms alone, which aligns with a sustainable garden approach. In literature and practice, this form of biological control is often mentioned as part of integrated pest management in the soil.

Leatherjacket control and controlling leatherjackets

Leatherjacket control essentially means three things: recognizing the pest, choosing the right moment, and applying a biological method that fits the leatherjacket's life cycle. Recognition often begins with damage patterns such as bare spots, loose turf, and birds pecking frequently in the lawn.

In lawns, most problems occur during two periods: after egg-laying and hatching in late summer or autumn, and again in early spring when larvae become more active in feeding. This is precisely why timing is so crucial when controlling leatherjackets. If you use nematodes, link this to conditions where they can move and survive in the soil, with sufficient moisture and a suitable soil temperature. Since nematodes only work if they can move, a moist soil and the correct temperature are essential when using nematodes against leatherjackets.

Combating leatherjackets can be done perfectly well without chemicals, and that's not a detail but a choice with consequences. Chemical agents often work more broadly than you intend and can also affect the soil life you need for a resilient lawn. Biological control of leatherjackets is more selective: you target the larvae while leaving the soil as an ecosystem as intact as possible.

Nematodes fit this idea because they naturally occur in soils, and their effect depends on conditions such as moisture and temperature. This also makes the approach fair: if the soil is too dry or too cold, nematodes perform less well, and it's wise to improve the conditions first instead of pushing harder with stronger agents.

When to control leatherjackets

When controlling leatherjackets is most effective depends on the stage of the larvae. The best chance is usually in the autumn, when young larvae are relatively small and closer to the surface, and in early spring when they become active feeders again.

Two factors are crucial for success. The soil must be moist enough because nematodes need water to move through the soil. And the temperature must be high enough to keep nematodes active. Practical advice often mentions a lower limit around 10 degrees Celsius as a guideline, with better activity at slightly higher temperatures. So, don't plan to combat leatherjackets on a random calendar week, but based on measurable conditions in your lawn.

How to control leatherjackets

How to control leatherjackets in a biological way works best if you cooperate with soil life. Nematodes seek out larvae in the soil, penetrate them, and eliminate them via their symbiotic bacteria. That's precisely why soil moisture and temperature are so crucial: without movement and activity in the soil, there is no effective search and no infection.

View this as population management rather than a one-time reset. If your lawn is susceptible, for example, due to consistently moist spots or a lot of crane fly activity, it helps to improve the conditions so that the grass recovers faster and is less vulnerable. Because you are working with biology and not hitting a reset button, natural control of leatherjackets in lawns always involves two tracks: tackling the larvae and improving the recovery capacity of the grass.

Controlling leatherjackets, the key points at a glance

You can most cleverly combat leatherjackets by coordinating timing, soil conditions, and a biological approach. Biological control is usually the most sustainable and safest route for a healthy lawn because you not only tackle the pest but also respect the soil ecosystem.

In the explanation below, you can read more about the biology of leatherjackets, their lifestyle, and how to control them naturally.