Plant Problem Diagnostic
Leatherjackets and Chafer Grubs in UK Lawns
The short answer
Lift a suspect patch of turf and look. Leatherjackets, the larvae of crane flies (daddy-long-legs), are greyish-brown, tubular, up to 30 mm long, with no legs and no obvious head. Chafer grubs are stout white larvae curved in a C shape, with light brown heads and three pairs of legs, up to 18 mm long. Both eat grass roots, turning patches yellowish-brown, and much of the visible wreckage is secondary: crows, jays, magpies and rooks stab small round holes in the turf, while badgers and foxes tear it up wholesale to reach the grubs.
Control for home lawns is biological, with timing doing most of the work. For leatherjackets, apply Steinernema feltiae or S. carpocapsae nematodes in September to early October; RHS notes that once damage is obvious the soil may already be too cold for nematodes to work. For chafer grubs, apply Heterorhabditis bacteriophora between July and September. Both need moist, well-drained soil at a minimum of about 12°C (nematodes work in roughly the 12-20°C range), watered in and kept moist.
Repair comes after the feeding ends: re-sow with grass seed or lay turf in mid to late spring, when RHS says chafer grubs have moved deeper to pupate, and concentrate nematode treatment on turf around the edges of affected areas where larvae spread.
Which grub have you got?
The two are easy to tell apart in hand. Leatherjacket: dull grey-brown, leathery, elongate and tubular, legless, no obvious head, up to 30 mm. Chafer grub: white and stout, permanently curled in a C, light brown head capsule, three pairs of legs behind the head, up to 18 mm; in the UK the garden chafer (Phyllopertha horticola) and Welsh chafer (Hoplia philanthus) are the usual lawn species.
Timing of damage differs too. Chafer grub damage peaks between autumn and spring as the larvae mature, and infestations can be very localised and sporadic, so one lawn on a street may be ruined while neighbours see nothing. Leatherjacket problems typically follow wet autumns when crane flies laid eggs into moist lawns.
The animal damage is usually worse than the grub damage
A moderate grub population thins and yellows turf, but the lawn is often destroyed by the diggers rather than the eaten roots. Corvids leave neat small round holes where beaks probed; badgers and foxes peel and shred whole sections overnight. If your lawn is being excavated, treat it as a strong sign of grubs worth confirming by lifting turf and counting, and accept that the wildlife will keep coming until the food supply drops.
Nematode treatment, by species and calendar
- Leatherjackets: water in Steinernema feltiae or Steinernema carpocapsae during September to early October as a preventive measure, before damage shows; by the time damage is visible the soil may be too cold for nematodes to be effective.
- Chafer grubs: water in Heterorhabditis bacteriophora from July to September, while soil temperature is in the 12-20°C range and grubs are near the surface.
- Both: soil must be moist but well drained, minimum around 12°C (54°F); water the lawn before and after application and keep it moist so the nematodes survive and move.
- Treat the turf around the edges of visibly affected areas as well, since larvae spread outward from problem zones.
- There are no chemical insecticides approved for home gardeners against these pests in UK lawns, so nematode timing is the whole game; RHS also notes healthy lawns tolerate low grub numbers, which also feed birds.
Repairing the lawn
Re-sow damaged areas with grass seed or lay fresh turf in mid to late spring, when chafer grubs have moved deeper into the soil to pupate and feeding pressure is off. Firm the surface, keep it consistently moist, and improve the sward's general vigour (feeding, aeration, autumn overseeding) so the lawn carries a background grub population without visible damage.
Sources
Reviewed 2026-07-18. We cite university Extension, government, and established horticultural sources — and never invent pesticide rates or dangerous treatments.
- RHS - Leatherjackets — Leatherjackets are greyish-brown, tubular, up to 30 mm, with no legs or obvious head; turf yellows and corvids leave small round holes probing for them; Steinernema feltiae or S. carpocapsae nematodes are applied September to early October into moist, well-drained soil at a minimum of 12°C, and soil may be too cold once damage is visible.
- RHS - Chafer grubs in lawns — Chafer grubs are stout white C-shaped larvae with light brown heads and three pairs of legs, up to 18 mm; garden chafer and Welsh chafer are the common species; crows, jays, magpies, rooks, badgers and foxes tear up turf for them; Heterorhabditis bacteriophora nematodes are applied July to September at 12-20°C soil temperature; re-sow or re-turf in mid to late spring when grubs move deeper to pupate.