18 February 2026

What’s eating my lawn – treating Leatherjackets and Chafer Grubs with nematodes.

Leatherjackets and Chafer Grubs are serious pests of lawns. Grass growth initially slows, yellow patches appear, PLUS the grass can be easily pulled up due to little or no root growth. Birds and animals may also pull at or dig up the lawn while searching for the grubs, causing further damage. As the infestation progresses, bare patches develop and the lawn can eventually be destroyed, making early chafer grub and leatherjacket grass treatment essential to prevent root damage. BOTH Leatherjackets and Chafer Grubs can be controlled organically using 2 different nematodes applied at the right time of year. The advantage of treating with nematodes is that they are safe for children, pets & wildlife & the lawn may be used immediately after treatment.

ABOUT LEATHERJACKETS :-

Leatherjackets are the grubs (larvae) of crane flies (Daddy Long Legs) and can quickly devastate a lawn. They feed just below the surface destroying the root system and the underground stems of the grass. Most damage is done in spring and autumn when they are actively feeding. Symptoms of an attack are that the grass turns yellowish brown in mid summer & birds, particularly starlings will peck at the lawn feeding on the leatherjackets.

What do they look like?

Leatherjackets are the larvae of the Daddy Long Legs / Crane Fly. They are about 4cms long, brown or greyish black, soft and fat but with a tough skin. They have no legs and no discernible head. They can be encouraged to the surface by placing a sheet of black plastic on the grass overnight and the grubs will come to the surface to feed. A positive identification can then be made.

What is the life cycle?

The adult Daddy Long Legs emerge in early September & often come into the house. They mate & lay up to 300 eggs on the lawn surface. These eggs hatch to produce small legless grubs, which start to feed on the grass roots. Feeding continues slowly throughout the autumn and winter. In the spring, they gorge themselves growing quickly. Through the summer they pupate and then push to the surface with the adults emerging in late summer.

ABOUT CHAFER GRUBS :-

Garden chafers feed on grass roots severing the root from the shoot. The grubs are most active in the late summer and autumn when they cause the grass to turn yellow and die. Because they are often present in large numbers whole areas of grass can be affected and the grass can be ‘peeled’ back to reveal the grubs below. The grubs are also an attractive food source for larger birds, hedgehogs, badgers and even foxes, which will do further damage as they search for the grubs to eat.

What do they look like?

There are number of species of chafer grubs – the most common / damaging is the garden chafer. The chafer grub is white, with an orange head & 3 pairs of legs. 2cms long, they curl up into a characteristic C shape when disturbed. They are often present in large numbers just below the soil surface.

What is the life cycle?

The adult chafer beetles emerge in late May/ early June. They are 1cm long with a metallic green head and body with brown wing cases. They mate immediately and the female burrows back down into the soil to lay her eggs. (Once infested, the same piece of turf continues to be affected over a number of years.) The eggs hatch in mid summer and the grubs start to feed on grass roots. Although they have legs, the grubs move very little. Feeding will continue until late autumn when the grubs burrow down into the soil to pupate. Adults emerge in late May/ early June.

CONTROL USING NEMATODES :-

Biological control using nematodes is the safe, effective method of control that will not affect children, pets and wildlife and the lawn is safe to walk and play on immediately after application. Nematodes are actually microscopic eelworms, invisible to the naked eye and come as a powder. These nematodes are perishable and needs to be kept in a fridge, so you won’t find it on a garden centre shelf – it needs to be sent fresh by mail order.

How does biological nematode control work?

These are two species of nematodes which are parasites of soft bodied lawn grubs and these can be used to treat either Leatherjackets or Chafer Grubs :-

Control Leatherjackets by applying Nemasys Leatherjacket Killer containing Steinernema feltiae nematodes.

Control Chafer Grubs by applying Green Gardener Chafer Grub Killer containing Heterorhabditis bacteriophora nematodes.

Nematodes occur naturally in the soil in very small numbers. By applying Nemasys Leatherjacket Killer or Green Gardener Chafer Grub Killer you can boost the number of these beneficial nematodes in the soil, so that the effective control of lawn pests can be achieved. Supplied as a powder, the nematodes are mixed with water & watered onto the lawn & then washed in, so that they are as close to the pest as possible. The nematodes swim in the soil water & will enter the pest. Once there, they release a bacteria which multiplies & helps the nematodes destroy the grubs. The pest will stop feeding, turns black, shrivels & dies, disintegrating harmlessly into the soil.

How is it applied?

The nematode powder is mixed with water and applied as a dilute solution to the lawn with a watering can fitted a Coarse Rose or use the NemaCan OR use an EasyNem Applicator attached to a hose for larger areas.

Are these nematodes dangerous?

Only if you are a chafer grub or a leatherjacket! They only attack these pests and are harmless to you, your children, pets and other wild life. This is particularly important in treating a lawn- you can let children and pets play on it immediately after application.

When should the nematodes be applied?

For the best results the nematodes should be applied to coincide with when the pests are newly hatched and feeding close to the surface – normally in the autumn. For the best results, the soil should be moist and warm. Alternatively you can apply at other times of the year when the leatherjackets / chafer grubs are discovered, but you MUST treat in the autumn as well.

Apply Leatherjacket and or Chafer Nematodes in Sept/Oct/Nov – This is the ideal time to treat as the soil is warm PLUS the leatherjackets / chafer grubs are newly hatched, the soil is warm (needs a daytime soil temp of 10-12c) and are the most susceptible to the nematodes, so if you have had leatherjacket / chafer grub infestation in the past or have discovered a leatherjacket infestation or your neighbours are infested and you want to keep them at bay, treat in Sept/Oct/Nov. When applying in the autumn, each nematode pack will treat 100 sqm.

Apply nematodes when leatherjackets are discovered – These nematodes are normally applied in the autumn as this is when the leatherjackets are newly hatched and most susceptible to the nematodes, but if you have discover leatherjackets (not daddy long legs) and / or chafer grubs at any other time of year i.e. in the spring/summer then you can still treat treat but the mature leatherjackets / chafer grubs are much harder to kill, SO you must treat in September as well.

Will fertilisers / chemicals / moss killer affect the nematodes?

The use of fertilisers, weedkillers and moss killers will not affect the action of the nematodes, so they may be used immediately after application. Help your lawn recover from a pest attack by feeding it and applying Mycorrhizal Fungi. Leatherjackets and Chafer Grubs attack the roots of the grass, which means it is less able to take up nutrients and water, so help the lawn restore its roots by applying Root Success and / or Lawn Feed. Bare patches can be repaired by over-seeding with our Lawn Repair Sticks.

How are Chafer Grub Killer and Nemasys Leatherjacket Killer despatched?

Nematodes are a perishable, living product, so they are sent out fresh by Royal Mail 1st class TRACKED post. Being a perishable, living product, it must be used before the expiry date (which is marked on the inside of the pack and will be at least 2 weeks) and it must be stored in the fridge until it is needed. Once opened, the contents do not keep, so it must be used in one day – do NOT store the made up solution or powder.

Available to buy now