Lawn guide
Leatherjackets and chafer grubs: spotting and fixing lawn damage
Brown patches that lift like a loose carpet, birds pecking at the lawn, foxes digging at night: these often point to grubs eating the roots. Here's how to tell, and what to do.
Meet the culprits
Leatherjackets are the larvae of crane flies (daddy longlegs). They're grey-brown, legless and tough-skinned, and they feed on grass roots and stems near the surface, mostly from autumn to spring.
Chafer grubs are fat, white, C-shaped grubs with brown heads and legs near the front. They live a little deeper and eat roots, especially in late summer and autumn.
Both are common in lawns across the North East, particularly after a mild, damp autumn.
Signs of grub damage
- Yellow or brown patches that get bigger
- Turf that lifts easily, with few roots underneath
- Birds pecking at the lawn more than usual
- Holes and scrapes from foxes or badgers
- Grubs visible when you lift a patch
How to check
Soak a patch
Water a damaged area well, then cover it overnight with a sheet or black plastic.
Lift the cover in the morning
Leatherjackets come to the surface and can be counted.
Or cut a small square
Lift a piece of turf at the edge of a brown patch and look in the top few centimetres of soil.
Treating grubs
The most effective garden treatment is biological: nematodes, microscopic worms that seek out and kill the grubs. They're watered onto the lawn when the soil is warm and moist, usually in late summer or early autumn. Follow the supplier's instructions on timing.
Keeping the lawn healthy also helps it shrug off light damage. Good drainage, regular feeding and not cutting too short make for stronger roots.
When to replace the lawn
If grubs have eaten away large areas, the lawn may be too far gone to recover well. Replacing it gives a fresh start: we lift the damaged turf, prepare the soil and lay new rolls. Treating for grubs at the right time of year is still wise afterwards so they don't move into the new lawn. See lawn replacement.
Common questions
Can new turf have grubs?
It's unusual, as cultivated turf is grown and harvested young. Grubs more often come from the surrounding lawn or soil.
Do crane flies always mean leatherjackets?
Lots of crane flies in late summer suggest eggs are being laid, so check the lawn the following autumn and spring.