What Are Leatherjackets in Lawns?

What Are Leatherjackets in Lawns?

Leatherjackets are the larvae of crane flies, more commonly known as daddy longlegs. These soil-dwelling pests feed on grass roots and can cause widespread lawn damage if left untreated. While the adult flies are harmless, their larvae can strip large patches of turf, leaving your lawn brown, uneven and prone to further stress. Identifying and managing leatherjackets early is key to preventing long-term damage.

What Do Leatherjackets Look Like?

Leatherjackets are grey-brown, legless grubs with a tough, leathery skinhence the name. They typically grow to around two to three centimetres long and live underground, feeding on grass roots and stems just below the soil surface. You’re unlikely to see them unless you dig into the lawn, but the signs of their presence become more obvious in spring and autumn.

Large infestations can be found just beneath the surface, especially in damp, shaded areas of lawn.

How Do Leatherjackets Damage Lawns?

Leatherjackets feed on the roots and base of grass plants, cutting off their water and nutrient supply. The result is patches of yellowing, thinning or completely dead grass. As the damage progresses, these patches can widen and blend into each other, leaving large, bare areas across the lawn. Birds, especially starlings, magpies and crowsoften tear at the lawn in search of the grubs, worsening the appearance and structure of the turf.

Heavy infestations can weaken the lawn to the point where it cannot recover without reseeding or returfing.

When Are Leatherjackets Most Active?

Leatherjackets typically hatch in late summer to early autumn, after adult crane flies lay their eggs in grass or moist soil. The larvae feed through autumn, become dormant over winter, and resume feeding in early spring. This two-season feeding cycle means damage can appear at multiple times of year, often peaking in spring when the lawn is already under stress from winter conditions.

Because leatherjackets live beneath the surface, they often go unnoticed until significant damage has already occurred.

How to Spot an Infestation

The first signs of leatherjackets are often subtle: areas of thinning grass, poor colour, or an unusually soft feel underfoot. If birds are pecking or pulling at the turf repeatedly, it's a strong sign that insects are present. To confirm, you can peel back a small section of turf or soak an area with water and cover it overnight with a black plastic sheet. If grubs surface by morning, leatherjackets are likely the cause.

Early detection is critical. Left unchecked, they can destroy large areas of lawn in just a few weeks.

What to Do About Leatherjackets

Once you’ve confirmed their presence, the best time to treat leatherjackets is in early autumn, when the larvae are small and most vulnerable. Biological control using nematodes (microscopic worms) is the most environmentally friendly and lawn-safe method. These are applied with water and infect the leatherjackets, killing them naturally in the soil.

For severe infestations, a full lawn renovation may be required, this can involve scarifying, aerating, and overseeding after the leatherjackets have been brought under control.

Final Word

Leatherjackets are a hidden but serious threat to lawn health. Recognising the signs early, understanding their life cycle, and taking appropriate action can prevent widespread damage. Whether you're seeing bird activity, unusual turf softness or patchy grass loss, it's worth investigating below the surface. With the right treatment, you can stop the damage and help your lawn recover fully over the next growing season.