Insects in New Turf: Leatherjackets & Chafer Grubs Explained
Larvae in freshly delivered turf are a sign of living soil, not a faulty product. Learn how to tell leatherjackets from chafer grubs, how much damage they really do, and your control options.
Diagnose the Problem
Insect larvae are occasionally found in the soil layer of freshly delivered turf — and it's worth knowing that this is normal. Turf is one of the most natural products you can buy, and it contains a vast array of living organisms, from beetle, fly and insect larvae, spiders, millipedes and earthworms down to microscopic life. The presence of these creatures is a sign of a healthy, living soil. Most insect larvae will cause no problems at all in your lawn; only occasionally do numbers get high enough to damage turf, and the usual culprits are the crane fly (daddy long legs) and chafer beetles.
Leatherjackets — grey, legless, leathery
The larvae of crane flies, up to 30mm long depending on age, with grey-brown leathery skin and no legs or distinct head. They feed on grass roots and sometimes come above ground at night to eat the leaves.
Chafer grubs — white with a shiny brown head
The larvae of chafer beetles: whitish with a distinctly shiny brown head and six legs. In freshly harvested turf they're up to 15mm long and are usually found curled distinctively in their tunnel.
Garden chafer is the common one
Several chafer species live in the UK, but the garden chafer is the one most commonly found. The largest and most damaging species, the cock chafer, is very unlikely to appear in turf rolls because its lifecycle is far longer than the time taken to grow a turf crop.
Birds pecking at the grass
Poor growth in an established lawn is sometimes caused by larvae feeding on the roots underground. Very often the first sign is simply birds starting to peck in the grass.
They may not have arrived with the turf
Insects of many types are common in gardens. Larvae could have come in with the turf, already been in the soil on site, or developed within a few months from eggs laid by adults after the turf was laid. If you've laid turf over the site of an old lawn, larvae may even be the reason the previous lawn struggled.
The Solution
The important point is perspective: any damage caused by these larvae is temporary, and it stops when the larvae metamorphose into adults and fly away. A healthy, well-fed lawn copes with them far better than a hungry one — which is a good reason to always use a pre-turfing fertiliser before laying turf.
Identify what you've found
Grey-brown, legless and leathery means leatherjackets (crane fly larvae). Whitish with a shiny brown head and six legs, curled in a tunnel in the soil, means chafer grubs. Both feed on grass roots; only leatherjackets come up at night to eat the leaves.
Remove larvae at delivery
If you can see leatherjackets or chafer grubs on the turf when it's delivered, simply pick them out as you roll the turf out and release them elsewhere. It's a quick job at that stage and reduces what ends up in your new lawn.
Feed the lawn so it can cope
A healthy, well-fed lawn is the best defence against larval feeding. Apply a pre-turfing fertiliser before laying, then keep to a sensible feeding programme once the turf has rooted and established, so the grass can grow away from any root damage.
Monitor rather than panic
Because chemical control is now so restricted, homeowners are advised to monitor their lawns and consider preventative or curative action if it's needed once the turf is laid. Watch for thinning growth, turf that lifts, and birds working the surface.
Use nematodes if treatment is needed
Biological control is available in the form of nematodes — microscopic parasitic worms that feed only on specific insect larvae. They must be applied at the correct time of year, in the optimum soil moisture and temperature, so follow the label carefully. Nematodes are economical on a small lawn, though impractical on a large field scale.
Know the right species for each pest
Nematodes for leatherjackets are normally Steinernema feltiae, while those for chafer grubs are normally Heterorhabditis megidis or H. bacteriophora. Buy the one that matches what you've identified in your lawn.
Understand what professional treatment means
Chemical control of insect larvae is only available in limited circumstances. Acelepryn is the only authorised chemical treatment currently available for leatherjackets and chafer grubs: a qualified professional lawn care specialist can treat your entire domestic lawn with it, but turf growers and sports turf managers are restricted to treating no more than 10% of their total surface area. That restriction makes chemical control financially unviable for commercial turf production and virtually impossible to target, since larvae in one area are likely to be in others too — which is why larvae are more likely than ever to be present in rolls of turf at the point of delivery.
Repair any bare patches
If larvae have thinned the lawn, rake out the dead material once the problem has passed, fork over the surface and overseed with a quality grass seed blend to knit the sward back together.
Use the Fertiliser Calculator
Work out how much pre-turfing fertiliser to apply before laying turf, and how much to feed the lawn afterwards.
Recommended Products
Shop Leatherjacket and Chafer Grub nematode treatments, pre-turfing fertiliser and grass seed to repair any damaged patches.
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Leatherjackets in Your Lawn: How to Identify and Control Them
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How to Get Rid of Chafer Grubs in Your Lawn
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