Leatherjackets are the larvae of the Crane Fly better known as the ‘Daddy Long Legs’.
Leatherjackets are about 2.5cm or 1″ in length, are greyish in colour and have no distinct head and NO legs. If you can clearly see a brownish coloured head and legs you are most likely looking at chafer grubs (see our information on the biological control of these).
The adults crane fly is actually harmless, however, it is the larvae which cause damage to the lawn. The adult crane fly lays hundreds of eggs in the soil during the autumn. The larvae then hatch and the grubs live in the soil, feeding on grass roots and stems until the winter and then again in the spring before they emerge as adults and the cycle begins again.
The obvious sign is that you will notice the presence of adult crane flies in the late summer/autumn, they may be flying low or resting on the grass. Look out for predators (such as birds, badgers, foxes) pecking or digging in the lawn to find the grubs. As with chafer grubs or you may see yellowing and dying grass on the lawn in patches where the grass is failing due to lack of root.
Leatherjackets operate in much the same way as the Chafer grubs and can be treated with biological control.
This is the use of pathogenic nematodes which infect the larvae with a bactium which ultimately causes the death of the larvae.