Lawn grubs (chafer grubs & leatherjackets)
How to recognise it
Patches of lawn that lift away like a loose carpet, sometimes with birds or foxes digging at the turf; white C-shaped grubs (chafers) or grey legless larvae (leatherjackets) visible in the soil.
Life cycle and conditions
Adult chafer beetles and crane flies lay eggs in lawns in summer; grubs feed on grass roots from late summer through autumn and into the following spring.
Prevention
Keep lawns healthy and deeply rooted with good general care, which tolerates some grub feeding without visible damage.
How to treat it
A biological nematode drench applied to moist soil in late summer/early autumn is genuinely effective if timed correctly, and has no impact on birds, pets or other soil life.
Chemical lawn grub treatments for amateur use are now very limited — the nematode drench above is usually the more practical and effective option regardless.